RAFAEL LANDÍVAR UNIVERSITY

SCHOOL OF ENGINEERING
DEPARTMENT OF INDUSTRIAL CHEMICAL ENGINEERING

DESIGN OF AN IMMERSION LINE

FOR THE PRODUCTION OF GLOVES FROM
NATURAL LATEX IN GUATEMALA

THESIS

ROBERTO ANTONIO CAHUEQUE TERREAUX

ID: 1014207

Guatemala, March 2, 2012

Central Campus
 RAFAEL LANDÍVAR UNIVERSITY
FACULTY OF ENGINEERING
DEPARTMENT OF INDUSTRIAL CHEMICAL ENGINEERING

DESIGN OF AN IMMERSION LINE

FOR THE PRODUCTION OF GLOVES FROM
NATURAL LATEX IN GUATEMALA

THESIS

Presented to the Council of the Faculty of Engineering

Rafael Landívar University

By:
ROBERTO ANTONIO CAHUEQUE TERREAUX

Prior to conferring the title of:

Industrial Chemical Engineer

In the academic degree of:

Bachelor's degree

Guatemala, March 2, 2012

Central Campus
 DEDICATION AND/OR THANKS

To God
For giving me life and allowing me to do the things I love.

To my dad and advisor

For being there for me always and for all the knowledge you have provided me throughout my career.

To MY MOM
For being with me, supporting me, and motivating me throughout my entire career.

To my sisters
For helping me when I need it, assisting me with problems I had and always being there.
keep myself with good behavior.

TO MY NIECE
For bringing joy to my life and always being by my side.

TO MY FRIENDS
Especially to Anne and Pedro, for always being with me in good times and bad and reminding me
that not everything is studying.
 EXECUTIVE SUMMARY

The present work entitled Design of a dipping line for the production of gloves
the use of natural latex in Guatemala emerged as an initiative aimed at encouraging
the industrialization of an agricultural product from Guatemala, latex, since 95% of it
export as raw material for industries abroad. The design and establishment of the
the dimensions of the necessary equipment were developed based on a desired production rate (420
pairs of gloves per day), as well as to process variables already established in other studies.
A material and energy balance of the process was also carried out, and the diagrams were established.
of operation, of workflow, and of route.

For this purpose, the design of the line was developed based on references from other studies.
it was taken into account that for the production of gloves immersions must be carried out
hormones in different solutions, for which a design was created that adapts to the conditions
established in these mentioned studies. Likewise, the establishment of the
dimensions based on a desired production rate.

Finally, a mass and energy balance was carried out in order to determine the
raw material requirements, as well as fuel. The diagrams of the
process (operation diagram, operation flow diagram, and route diagram), with the
to determine the number of operations that are carried out, as well as the time required
for each of them.

Desired production rate, glove characteristics.

1
INDEX

MARCO I

I. INTRODUCTION........................................................................................................................2
1.1 What has been written on the subject...................................................................................3
1.2 Critical summary of the theoretical framework.........................................................5
5
Latex
1.2.3 Centrifuged latex .....................................................................................................6
1.2.3.1 High ammonia centrifuged latex.................................................................6
1.2.3.2 Centrifuged latex under ammonium.........................................................6
1.2.4 History and current situation of latex in Guatemala
1.2.5 Latex extraction process...................................................................................7
1.2.6 Gloves .......................................................................................................................8
1.2.7 Natural latex gloves for domestic use ................................................................9
1.2.8 Glove production process............................................................................10
1.2.9 Raw materials.........................................................................................................13
1.2.10 Molds used in the glove production process....................................15
1.2.11 Building materials for equipment ...................................................................15
1.2.12 Immersion tanks .............................................................................................16
1.2.13 Vulcanization
1.2.14 Coagulation
1.2.15 Size ...................................................................................................................19
1.2.16 Dimensions............................................................................................................19
Production rate

MARCO II

II. STATEMENT OF THE PROBLEM..................................................................................20

2.1 Objectives
2.1.1 General objective........................................................................................................22
 2.1.2 Specific objectives ................................................................................................22
2.2 Hypothesis
2.3 Variables
2.3.1 Independent variables ..........................................................................................23
2.3.2 Dependent variables .............................................................................................23
2.4 Definition of variables
2.4.1 Independent variables ..........................................................................................23
2.4.2 Dependent variables .............................................................................................25
2.5 Scope and limits ................................................................................................................26
2.6 Contributions

MARCO III

III. METHOD ................................................................................................................................29

3.1 Subject....................................................................................................................................29
3.2 Instrument
3.3 Procedure.......................................................................................................................33
3.3.1 Equipment sizing ...................................................................................33
3.4 Design and statistical methodology ........................................................................................34

MARCO IV

IV. PRESENTATION AND ANALYSIS OF RESULTS...........................................................35

4.1 Dimensions of the equipment .................................................................................................35
4.2 Design of the immersion line for glove production .......................................................... 38
4.3 Process Diagrams .........................................................................................................56
4.3.1 Process operation diagram.................................................................56
4.3.2 Flowchart of operations of the process .........................................................58
4.3.3 Process flow diagram...........................................................................60
4.4 Mass and energy balance of the process...............................................................................61
MARK V

V. DISCUSSION OF RESULTS............................................................................................62

MARCO VI

VI. CONCLUSIONS...................................................................................................................75

MARCO VII

VII. RECOMMENDATIONS

MARK VIII

VIII. BIBLIOGRAPHIC REFERENCES..................................................................................78

MARCO IX

IX. ANNEXES.................................................................................................................................81
TABLE OF CONTENTS

TABLE NO 1 CHARACTERISTICS OF NATURAL LATEX GLOVES.................................9

TABLE NO 2 ADVANTAGES AND DISADVANTAGES OF HORMONAL MATERIALS ..............................15

TABLE NO 3 TIMES BY WORKSTATIONS...................................................35

TABLE NO 4 REQUIREMENTS AND DIMENSIONS OF MOLD PLATES ......................35

TABLE NO 5 DIMENSIONS TANKS # 1, 2 AND 5.........................................................35

TABLE NO 6 DIMENSIONS TANKS # 3 AND 4....................................................................36

TABLE NO 7 IMMERSION CAR DIMENSIONS........................................................36

TABLE NO 8 OVEN CART DIMENSIONS........................................................36

TABLE NO 9 OVEN DIMENSIONS .....................................................................................37

TABLE NO 10 OPERATIONS DIAGRAM SUMMARY ................................................57

TABLE NO 11 FLOWCHART OF OPERATIONS .................................................58

TABLE NO 12 SUMMARY FLOW DIAGRAM OF OPERATIONS .............................59

TABLE NO 13 ENERGY BALANCE .................................................................................61

TABLE NO 14 DATA FOR ENERGY BALANCE RESOLUTION ............................89

TABLE NO 15 SPECIFICATIONS PULLEY .................................................................94

INDEX OF FIGURES

FIGURE NO 1 ISOPRENE POLYMER ..............................................................................5

FIGURE NO 2 LATEX EXTRACTION PROCESS 'PICK'........................................8

FIGURE NO 3 IMPULSOR

FIGURE NO 4 VULCANIZATION ............................................................................................18

FIGURE NO 5 CERAMIC HORMAS ....................................................................................30

FIGURE NO 6 CONVECTION OVEN ....................................................................................31

FIGURE NO 7 ELECTRIC PULLEY .........................................................32

FIGURE NO 8 OPERATIONS DIAGRAM.....................................................................56

FIGURE NO 9 ROUTE DIAGRAM .........................................................................60

FIGURE NO 10 MASS BALANCE ......................................................................................61

FIGURE NO 11 BAKING PROCESS DIAGRAM...............................................86

 I. INTRODUCTION

Currently, natural latex is a significant product for the country's economy, as

It is the fourth product that generated the highest income from exports during the year.
2,010, placing it below coffee, banana, and cardamom (Source: Bank of Guatemala). The
The price of this product is managed through a foreign currency, meaning its price fluctuates.
according to international market variables, which represents a disadvantage for Guatemala,
since if the price of the stock market decreases, the income to the country also decreases due to

exports. 95% of the latex produced in Guatemala is exported. Only 5% is

used in the country, according to Grupo Entre Ríos (2011), in the shoe, leather industry, among
others, this is due to the lack of industry in the country to process latex and obtain
final products, which represents a great opportunity for the Guatemalan industry. To
develop this type of industries, among which the manufacturing of
balloons, gloves, condoms, among others, can eliminate the dependence on income
(for export) of this product, since the price of a final product is not established
through a bag.

The objective of this work is to design a dipping line for production.

from natural latex gloves in Guatemala, determining all the equipment and materials
necessary prerequisites for this process, so that its assembly can be carried out by
any individual or company, thus promoting the industrialization of rubber.
Likewise, the production of gloves has advantages over companies that are dedicated to
same business abroad, as they must bear transportation costs to their
locations.

The importance of this thesis lies in the fact that the industrialization of latex represents a
economic growth for Guatemala, regarding exports of this product,
since profit margins would be obtained from both the sale of latex as well
for the manufacturing of it. The Industrial Chemical Engineering career is important, as
What can be done to encourage future generations to pursue studies related to manufacturing.
of latex, but encompassing different products, such as balloons, condoms, or any other
industry that is not present in the country.

2
1.1 WHAT IS WRITTEN ON THE SUBJECT

Velásquez (2007) in his Graduation Work titled Determination of production,

content of dry rubber, latex diagnosis and plasticity in 25 clones of hevea brasiliensis
(Euphorbiaceae) at Santa Ana Mixpiya farm, San Miguel Panan, Suchitepéquez, whose main
The objective is to know the production, the dry rubber content (DRC), latex diagnosis and
plasticity of 25 clones of Hevea brasiliensis, Muell arg. during the rainy season, under conditions
edaphic and climatic characteristics of the place. It was evaluated through a statistical design
completely at random, with a total of 25 clones (specific type of tree) 4 repetitions and 6
plants per experimental unit, with a picking intensity every three days, with concentrations
from Ethephon (2-chloroethyl phosphonic acid) at 5%. As results were obtained in terms of
the production and treatment that showed the best response was the IRCA 230 (one type of the 4
treatments used) in DRC, all treatments statistically produce the same
amount of dry rubber, as well as the plasticity.

Morales (2008) in his Graduation Thesis titled Pre-Feasibility Study of

assembly of a Natural Rubber Processing Plant, whose main objective is to determine
the Pre-Feasibility of installing a Natural Rubber Processing Plant in Escuintla, the
which will manufacture a type of rubber: technically specified rubber (TSRN-10); to achieve
to achieve this objective, market, technical, organizational, financial studies, and by
Finally, a work plan is developed for the installation of the plant. This financial study includes
the project's profitability, with an internal rate of return of 30% per year; it also establishes
that the industrialized process of rubber processing through modern machinery and
automated, in combination with other factors allows for the obtaining of production costs
competitive.

Cahueque (2,008) in his Graduation Work titled Evaluation of two agents

coagulants for natural latex, in the immersion production of household type gloves, whose
The main objective is to conduct an evaluation of three recommended coagulating solutions for the
formation of natural latex film in the production process of domestic-type gloves by
mold immersion. The coagulant solutions to be compared are: calcium nitrate in solution
aqueous, calcium nitrate in alcoholic solution and acetic acid in aqueous solution.

3
 Hernández (2009) in his Graduation Thesis titled Feasibility Study for the
production and export of rubber in Guatemala, whose main objective is to determine the
feasibility of setting up a processing and exporting plant for natural rubber in Guatemala
which will manufacture three different types of rubber: technically specified rubber (TSRN-10),
centrifuged latex and smoked leaves. To achieve this objective, studies were conducted on
market, technical, organizational and financial. According to the financial study, it was concluded
that the project is economically viable with a net present value (NPV) of Q5,248,606.39 and
an internal rate of return (IRR) of 42.28%.

Barrios (2010) in his Graduation Thesis titled Determination of the percentage of

solids, pH, and optimal residence time of NBR latex to obtain the standard gauge in
nitrile gloves, define parameters for certain variables (solid percentage, pH, and time)
residency) in the production process of nitrile gloves in order to obtain the product
in acceptable quality limits. As conclusions, it was determined that the percentage of solids is
42.02%, the pH must have a value of 9.12 and the residence time is 39.60 seconds.

4
1.2 CRITICAL SUMMARY OF THE THEORETICAL FRAMEWORK

1.2.1 Rubber

According to Hernández (2009), rubber is "a substance of great elasticity that is

obtained by exudation and coagulation of the sap from the rubber tree (Page 3). This
The gum tree belongs to a family of trees that falls under the genus
"Hevea," and the name of the tree is Hevea Brasilensis (since its origin is from
Brazil). Rubber is composed of the following:

Hydrocarbon rubber 94.00%

Acetonic extract 2.50 %
Proteins 2.50%
Ashes 0.30 %
Volatile materials (including moisture) 0.50 %

The main component of natural rubber is the polymer of isoprene called:

cis-1,4 polyisoprene

Figure No. 1: Isoprene Polymer

Source: Cahueque (2008)

1.2.2 Latex

According to Morales (2008), latex is "an aqueous colloidal suspension, in which the
rubber remains dispersed in the stable continuous aqueous phase" (Page 4). This
It is obtained through the bleeding of the Hevea Brasilensis tree and contains
approximately 30% dry rubber (Velásquez, 2007), which
subsequently it is concentrated by centrifugation, cremation, or
evaporation, according to Cahueque (2008). Latex is a dispersion that involves
5
 two phases, a dispersing medium, and a dispersed phase. The dispersing medium is
the water and the dispersed phase is made up of solid rubber, mainly the
isoprene polymer.

1.2.3 Centrifuged latex

Centrifuged latex is used in the production of rubber gloves.
According to Velásquez (2007), "it is an aqueous suspension of particles,"
produced by centrifugation of fresh latex, sourced from the plantations,
under strict control standards to make a uniformly elastic product
Latex is centrifuged until a uniform product is obtained, this
the process is carried out with a preservative, mainly ammonia, and a
second, in smaller proportion, potassium hydroxide (KOH). It has
approximately 60% solids (mainly natural rubber). This is the type
From commercially distributed latex, there are two types: High Ammonium and Low.
Ammonium.

1.2.3.1 High ammonium centrifuged latex

According to Barrios (2010), this type of centrifuged latex is "natural latex with a
ammonia treatment, which increases its stability, The pH of this latex
oscillates between 11 and 12” (Page 6).

1.2.3.2 Centrifuged latex under ammonium

According to Barrios (2010), this type of centrifuged latex 'is combined with oxide.
of zinc and some accelerator like tetramethylthiuram disulfide to stabilize the
polymer with a pH close to 10" (Page 7).

6
1.2.4 History and current situation of latex in Guatemala

Natural Rubber has been known in Guatemala since the Mayan era, although, until the
20th century, its cultivation and processing took on an industrial dimension. The cultivation of

natural rubber production in the country has increased and most of the rubber obtained is exported,

mostly to Mexico, without being manufactured. (Source: Grupo Entre Ríos,

2011

According to the Entre Ríos Group (2011), rubber plantations in Guatemala

exceed 80,000 hectares with more than 28 million trees and a volume
of production of more than 75,000 tons of dry rubber per year. This data
statistics position Guatemala within the American hemisphere as the
second producer, the largest exporter and the country with the highest growth rate
high of Natural Rubber.

Currently, their main export markets are North and South America;
generates around 20,000 direct jobs and 60,000 indirect jobs.
it can be mentioned that approximately 95% of the rubber produced in Guatemala
is exported and manufactured abroad. (Source: Grupo Entre Ríos)

1.2.5 Latex extraction process

The process of extracting latex from the Hevea Brasilensis tree is called
bark, which involves making a cut along the trunk of the tree
approximately half circumference, with a blade, the tree bleeds latex,
which falls into a plastic container, which is attached to the tree. In this
a substance that acts as an anticoagulant is found in the container, it is generally used

ammonia between 3% and 5%; the pica can be done between 100 to 150 times a year,
which amounts to 2 to 3 times a week, according to Morales (2008).

7
 Figure No. 2: Latex Extraction Process 'Pica'

Source: Hernández (2009)

1.2.6 Gloves
There are different types of gloves, depending on their use, they are manufactured
of different types of materials, among which natural latex can be mentioned
and synthetic polymers such as neoprene. The design of the gloves depends on the
application, as well as the material used to manufacture them.

Gloves can be classified, according to their use, into three main groups,
according to Cahueque (2008), the groups are as follows:

Medical use
Household use
Industrial use

Within these three groups, there are different divisions, for example, in the group of
industrial use, there are special gloves with high heat resistance, for
manipulating objects at high temperatures, there are also reinforced gloves,

8
 to be able to handle sharp objects. According to this, the characteristics of the
gloves vary depending on the application. Household gloves,
according to Cahueque (2,008), 'they are generally made of natural rubber, they have
low level of protection for the hands and many times the quality of them is
perceived by customers in its appearance and in its duration under conditions
lightweight usage (Page 26).

General parameters evaluated in gloves include

length, caliber, texture, color, elongation, shear resistance, permeability to
different chemical products, among others.

1.2.7 Natural latex gloves for domestic use

The design of the immersion line in this thesis will be focused on production.
of natural latex domestic type gloves. A natural latex glove of type
Domestic must meet the following characteristics:

Table No. 1: Characteristics of Natural Latex Gloves

Property Characteristics
Appearance Natural rubber gloves in various colors
Wide 29-32 centimeters
Caliber 0.35-0.46 millimeters
Source: Cahueque (2008)

9
1.2.8 Glove production process

The production process corresponding to the design of this thesis is through a

immersion process. The process consists of immersing molds that have
glove shape in different tanks, this in order to form a film of
latex on the mold, to later remove the glove from the mold. The
the first step is to "have a suitable last in optimal conditions of
finishing and cleaning, to subsequently apply a uniform film, without
defects, of coagulant on top of it" (P. 5), according to Cahueque (2008).

According to Barrios (2010), the process of preparing the mold consists of three
stages. The first stage consists of immersing the last in a solution of
EDTA (ethylenediaminetetraacetic acid) aims to remove metals
heavy metals as well as compounds that make up hard water. The second stage
consists of immersion in water at 70 ºC, with the aim of cleaning the mold of the
EDTA solution. The third stage consists of immersing the last in a
Solution of ethoxylated alkylphenol at 60 ºC, aims to wet the
horma. The residence time for each of the tanks is approximately
one minute and a half.

Subsequently, the mold should be "immersed in a coagulant solution, to

leave a movie of the same about the mold” (Page 5), according to Cahueque (2008);
the function of the coagulant in the process is 'the immobilization of the particles of
the dispersed phase (rubber), the dispersion medium (water) is trapped between the
rubber particles, which will be removed by heating in the ovens.

According to Barrios (2010), immersion should be done in a coagulant that possesses a

concentration between 20% and 40% at a temperature of 50 ºC, the time of
The residence time of the mold in this solution is approximately 20 seconds.

10
According to Barrios (2010), because latex is a colloidal emulsion, it
it behaves like a liquid and for this reason it is important that it is modified to
obtain a much stronger form of the raw material through the
coagulation.

The colloidal suspension, that is, latex, has an ionic equilibrium, due to the fact that
the surface of the rubber molecules that are charged
negatively, so these droplets do not unite with each other (like charges
(repel). When no component other than latex is added, the loads
Ionic charges remain, so they remain suspended and the
ionic equilibrium. When adding a coagulant, the ionic equilibrium is altered, so
that the rubber molecules join or agglomerate, thus allowing the latex in
coagulate, this is a non-reversible process.

Next, a immersion of the mold in latex is performed, which contains

a mixture of chemical additives for the process to take place
vulcanization of latex; the formation of the film on the mold is possible
due to the action of the coagulant on the latex. According to Barrios (2,010), the
the immersion of the mold in the latex tank must be carried out with a time
of residence between 20 and 40 seconds and its temperature can be at
a range between 30 ºC and 35 ºC.

According to Barrios (2010), 'in the post-coagulation latex industry, it is necessary to'
carry out another chemical process known as vulcanization (Page 9). The process
vulcanization causes a change in the properties of the molecules of
rubber, considerably increasing its hardness, this is carried out
by the action of sulfur and other chemical additives.

These additives modify the polymer by forming bridges known as

crosslinks between each individual polymer chain allowing them to
chains are joined" (p. 9), according to Barrios (2010).

11
There are different characteristics of rubber that change after the process.
of vulcanization. The stickiness of the material can be mentioned, which
decreases with the vulcanization process, for example, natural latex is used
like glue in different industries, including the footwear industry, on the other hand,
vulcanized latex, which can be found in products such as caps for
swimming, it is not sticky. It can be mentioned that rubber increases its hardness and
they improve their mechanical properties. Some examples of materials
Common vulcanized products are automobile tires, shoe soles, hats
of swimming, condoms, balloons, elastic components of cars, gloves and
mouthpieces for wind instruments.

Due to the fact that various synthetic rubbers have currently been produced, there exist
different methods for vulcanizing, depending on the type of rubber being used
Vulcanizing. There are 4 methods, which differ by the chemical additive.
that is used for vulcanization, since these additives must be compatible with the
rubber molecules. The 4 methods are followed by a heating.

The methods for vulcanizing are:

Sulfur systems (For natural rubber).

Peroxides.
Urethane.
Metal oxides. (Barrios, 2010)

The final stage of the process, the glove molds with the latex film are
they pass through an oven. This oven serves two basic functions,
drying of the film and vulcanization of the rubber particles. According to Cahueque
(2,008), the drying phase seeks to release the water trapped in the film in the
moment that the latex formulation coagulates and the vulcanization phase is in the
What are the vulcanizing agents and accelerators that chemically act with latex?

12
 to give the desired properties to the rubber. The temperature for drying must
the temperature should be 80 ºC and the vulcanization temperature should be 120 ºC.

Heat transfer in the oven is done by convection and can be operated

with thermal oil or with propane, the approximate residence time in the furnace
It is 1 hour and 15 minutes, according to Barrios (2010), however, for gloves of
natural latex the time can be reduced to 1 hour, with 30 minutes of drying and 30
minutes of vulcanization. This residence time in the oven can be reduced,
depending on the type of rubber used (natural or synthetic) and the mixture of
the additives that are added to the latex for the vulcanization process.

1.2.9 Raw materials

The raw materials used in the glove production process, apart from
of natural latex, are the following:

Coagulant:
Different substances can be used in the glove production process.
as coagulants, among which calcium nitrate can be mentioned and the
calcium chloride. The coagulant, according to Cahueque (2008), is "the substance
chemistry that, when added to a colloidal system, comes into contact with it,
provoking its coagulation" (Page 3).

Chemical Additives:
A mixture of different chemical compounds that fulfill the
function of vulcanizing rubber molecules. Chemical additives are
they add to the latex in a dispersion, which contains a mixture of
vulcanizers, accelerators, stabilizers, as well as other additives with different
functions depending on the type of glove to be produced. Next,
they will describe the main chemical additives:

13
Vulcanizing agent: According to Cahueque (2008), 'a vulcanizing agent is a substance

chemistry that participates in the bonding of the vulcanization reaction (Page.

The most commonly used chemical compound to carry out the reaction
vulcanization is sulfur, according to Barrios (2010).

Accelerator: According to Cahueque (2008), an accelerator is a 'substance'

"chemistry that accelerates the vulcanization process" (Page IX), by
Thus, these reduce the reaction time. The speed of
vulcanization and the properties of the final product depend on the mixture
of vulcanizers, activators, and accelerators that are added to latex.

The stabilizer: According to Cahueque (2008), a stabilizer is a substance

added to the colloidal system (latex) that provides resistance to prevent
its coagulation (excessive)" (Page XI). Due to the fact that the coagulation in the

latex is desired for the glove manufacturing process, the amount of

The stabilizer that is added to the latex is important, as it must be added to
in such a way that this process is not avoided.

Antioxidant: Because oxygen attacks and degrades molecules of

latex, the properties of the latex film that forms on the mold
they can be affected, which is why antioxidants should be added to
preserve its properties. According to Barrios (2010), there are two
types of chemical compounds used as antioxidants, the type of
phenolic chemical compounds and the type of amines. For the production of
Gloves use amines as antioxidants, as they show lower
decoloration of the final product.

Activators: According to Barrios (2010), the vulcanization reaction that

producing sulfur for latex molecules would require excessive heat
to take place, so the high temperatures could destroy the
polymer by oxidation of the molecules, so they must be added

14
 activators, so that the reaction temperature is not so high, one can
use zinc oxide or sulfur oxide as an activator.

1.2.10 Molds used in the glove production process:

The molds are the base on which the latex film will be formed. It is important
the quality and finish of the lasts, if these quality standards are not maintained,
defects can occur in the glove. The main characteristics of the
the hormones are as follows:

Thermal Resistance (preferably to temperature changes, as it

they perform the same in the glove production process.
Excellent finish quality
Easy to Clean

The lasts can be made of wood, metal, or ceramic, each material has
its advantages and disadvantages, which will be described in the following table:

Table No.2: Advantages and Disadvantages of Mold Materials

Material Mold Advantages Disadvantages

Wood Low Cost They can be deformed by heat.
Metal Durable High Cost
Ceramics Durable Brittle
Source: Cahueque (2008)

1.2.11 Construction Materials for Equipment

According to Baasel (1990), the construction materials for equipment are chosen
according to the characteristics of the materials that will be used and the conditions of
functioning. The material mostly used in the industry is steel.
carbon (does not include stainless steel), however, it is not used for
temperatures below -45.6 degrees Celsius (loss of ductility and strength)

15
 impact), or temperatures above 510 degrees Celsius (loss of hardness).
It is also not used with acidic products, because it does not have
a high resistance to corrosion.

According to Helmus (2008), the construction materials of the equipment not only
depend on the process, but also on the costs they represent within a
process. Below are some important characteristics to consider
it is important to consider at the time of choosing the construction materials for equipment in general:

Pressure and temperature.

Material composition (corrosion resistance).
Costs (maintenance).
Available modifications.

1.2.12 Immersion tanks

The immersion tanks are the equipment that contains the raw materials that
they will be added to the glove. They must have the following characteristics,
according to Cahueque (2008):

The building material must allow for easy cleaning and make it easy
the removal of rubber. The material must be corrosion resistant, it
recommend stainless steel.
It is preferable that they have mechanisms to control the temperature of the
product that contains.
To have a controlled agitation system, not very fast, so as not to generate
the bubble is not very slow to avoid dead spots on the surface.
It is advisable to have double bottoms (tanks 3 and 4) to catch
wastes or pollutants that settle in the first bottom and prevent
circulate with agitation.
It is necessary that they have a feed valve system in the
background, in such a way that no air is incorporated at the moment of
feed it.

16
 A system to close it for the moments when it is not in use will help to
Prevent the formation of scabs and/or contamination of the product.

According to Walas (1990), the dimensions and shape of a tank, the arrangement of
Impellers and casings (internal structure) are factors that influence quality.
from the agitation of a liquid within it. These factors depend on the
objectives of the operation, such as agitation inside a reactor or the
homogenization of a solution, as well as the properties of the fluid within
of the tank. The dimensions and shape of the tank depend on the amount of
liquid that will contain, as well as the performance of some secondary operation
(aside from storage). The use of drivers and housings within the
Tanks depend on the type of fluid that will be stored and the requirements of
agitation of the process. The purposes of the equipment are described below
mentioned

Impetus: used to give movement to the contained liquid

inside a tank. The shape of the impeller and its position inside the
tank depends on the objective of the agitation, for example, suction
of the liquid. Below is an image of an impeller.
used to create a suction effect:

Figure No. 3: Impeller

Source: Walas (1,990)

17
 Housing: It is an internal structure inside the tank, they have
different functions, among which can be mentioned the
direction of a suction effect.

1.2.13 Vulcanization
According to Cahueque (2008), "it is the process by which rubber is heated.
raw in the presence of sulfur, in order to change certain properties, such as its
hardness and heat resistance" (Page XIII). Below is a figure
that illustrates the vulcanization process:

Figure No. 4: Vulcanization

Source: Cahueque (2008)

1.2.14 Coagulation
According to Cahueque (2008), coagulation is the 'process by which latex
it is destabilized and an aggregation or accumulation of the phase is caused
"dispersa, separating from the medium of dispersion" (Page X). Which means that the
rubber molecules (isoprene polymer) group together, resulting in
adhered to the mold in the glove production process.

18
1.2.15 Size
Size refers to the amount of volume that occupies space.
(McGraw Hill Encyclopedia, 2011).

1.2.16 Dimensions
This concept refers to the length, extent, or volume of any
instrument, equipment, or anything else (McGraw Hill Encyclopedia, 2011).

1.2.17 Production rate

Quantity of product per unit of time (McGraw Hill Encyclopedia, 2011).
As an example for the glove production line, the production rate
It can be 100 gloves per hour, as it refers to the quantity of gloves that
must be produced within a certain amount of time.

19
 II. STATEMENT OF THE PROBLEM

Guatemala is a country with great growth potential regarding a product, rubber.

(natural latex), according to statistical data, the production level is over 75,000 tons
per year, and it is expected that by the year 2020 this amount will double, the country is positioned
as the second producer (only surpassed by Brazil), the largest exporter and the country
with the highest growth rate of Natural Rubber in all of America, according to Grupo Entre
Rivers.

Natural rubber makes an important contribution to the Gross Domestic Product generated by its
exports, mainly to Mexico and the United States; for the year 2010, the
Rubber exports totaled 237.4 million dollars, a figure that has been increasing.
in recent years, according to the Bank of Guatemala. In addition, between the year 2009 and 2010 was
the second traditional product with the highest growth.

Based on this data, it is concluded that this product will continue to increase its contribution with the

passage of time, although this is not entirely true, this is due to the fact that rubber is a product
which manages its price through an exchange, so it varies over time, with increases
or decreases depending on market variables. The price of rubber is dependent
of the price of oil, since synthetic rubber is obtained from oil, which is a product
substitute for natural rubber, so when the price of oil decreases, it also decreases the
price of rubber. Due to the fluctuation in the global market price, the growth of
exports are unpredictable, according to statistics from the years 2008 and 2009, since
exports (in money) decreased by 30%, this due to the price of rubber
decreased from $3.20 to $1.20 per kilo, despite the amount of product exported being
mayor, according to Urías Gamarro.

According to the situation of rubber in the market, it is deduced that a change is necessary in the
management of natural rubber for economic growth that exports present
the country, is not hindered by the stock price. The effect of this problem can
reduce by diversifying marketing towards final products (gloves, balloons, among others)

20
others), so that these can then be exported to other countries, and due to the prices
These final products are not handled by the stock market; there would be no decreases in value.
monetary aspects of exports for Guatemala. Therefore, the objective of this work
It consists of designing an immersion line for glove production.
starting from natural latex in Guatemala, which raises the following question: Is it feasible the
establishment of the design of an immersion line for the production of rubber gloves
natural in Guatemala?

21
2.1 OBJECTIVES

2.1.1 General objective

Design a dipping line for the production of gloves from
natural latex in Guatemala.

2.1.2 Specific objectives

Establish the operation diagrams, the operation flow diagrams, and the route diagrams.
for the glove production process.

Determine the ideal number of lasts that each plate should contain.
hormas, as well as their dimensions.

Determine the dimensions of the tanks that will be used to carry out the
immersions.

Determine the dimensions of the oven that will be used for the drying process.
vulcanized.

Carry out the material and energy balance of the process.

2.2 HYPOTHESIS
Not applicable because it is a design project, so the formulation of it is not required.
a hypothesis, according to the established guidelines for carrying out graduation work of the
Rafael Landívar University (2009): "These are only included in studies of a character
experimental or comparative descriptive." (Page 26)

22
2.3 VARIABLES

2.3.1 Independent variables

Total time online for Immersion

Total time in Oven
Production rate
Glove size
2.3.2 Dependent Variables

Dimensions of the mold plates

Dimensions of immersion tanks
Dimensions of the oven

2.4 Definition of variables

2.4.1 Independent variables

Total time in the immersion line

Conceptual Definition: "total time that passes to form the film of"
latex in the mold" (p. 15), according to Barrios (2010).

Operational Definition: it is the time from when a molding plate enters the
immersion line until it exits it. The plate upon leaving the line of
immersion brings with it the latex film, which will subsequently form the
glove, after the latex has been vulcanized.

23
Total time in oven

Conceptual Definition: 'total time that elapses to carry out the process'
drying and vulcanization inside the oven" (Page 18), according to Barrios (2010).

Operational definition: it is the time that elapses for it to take place

drying and vulcanization process for the latex film formed on the molds
of gloves. This time depends on the type of glove that will be manufactured, as well as the
material, whether natural or synthetic rubber.

Production rate

Conceptual Definition: "amount of production per unit of time"

950) (McGraw Hill Encyclopedia, 2011).

Operational Definition: the production rate determines the requirements of the

immersion line, as well as the dimensions of the equipment to be used in the
same. For this design, it is a constant, 420 pairs of gloves per day (rate of
production obtained according to the industry's requirements.
Size of lasts

Conceptual Definition: 'amount of volume in space' (Page 975) that

The molds are occupied (McGraw Hill Encyclopedia, 2011).

Operational Definition: the size of lasts is established according to the

specifications of the glove that will be produced. For this design, the glove to
producing is of domestic type, so the height of the molds is
between 14 and 16 inches.

24
2.4.2 Dependent variables

Dimensions of the mold plates

Conceptual definition: 'length, extension, or volume' (Page 453) of the plates

of molds, (McGraw Hill Encyclopedia, 2011).

Operational Definition: the dimensions of the molds are

established based on the daily production rate, as they are determined by the
number of molds that each mold plate must contain in order to comply with the
established daily production rate.

Tank dimensions

Conceptual Definition: 'length, extension or volume' (Page 453) of the

immersion tanks (McGraw Hill Encyclopedia, 2011).

Operational Definition: the dimensions of the tanks are established from

of the size of the molds, as well as of the plate that holds them.

Oven dimensions

Conceptual Definition: 'length, extension or volume' (P. 453) of the oven

(McGraw Hill Encyclopedia, 2011)

Operational Definition: the dimensions of the oven are determined based on the
production rate, the size of the mold plate, and the size of the mold to be used.
It is established based on meeting the established production rate.

25
2.5 SCOPE AND LIMITS

Scopes

This thesis is based on the design of a immersion line for production.

gloves made from natural latex in Guatemala. The establishment of the dimensions of the
the line was determined by four independent variables, the production rate of
gloves; the size of the mold which is specified according to the type of glove to be produced, in
this case is a domestic glove so the length of the mold is between 14 and 16
inches; the total time in the immersion line and the total time in the oven. The time in
the furnace is the bottleneck of the process, from it the dimensions were established
the teams according to meet the desired production rate. The size of the
teams based on the four independent variables.

The objective of the work was to carry out the design (shape) and the establishment of the dimensions.
size of the immersion line for glove production, as well as all equipment
necessary for it, such as the oven, which is necessary for the drying process and
vulcanization of rubber, after the film has formed on top of the mold.

For this work, quotes were not taken into account to make an analysis of the
costs that the installation of this line would represent, the raw materials that were not specified
They can be used in the mixture of vulcanizers, accelerators, and stabilizers.

The purpose of this work was to provide a tool to any entrepreneur.

Guatemalan, related to the rubber industry, in order to carry out a process of
industrialization of it, since 95% of the rubber produced in Guatemala is
exported as raw material and not as a final product. Likewise, it is possible to obtain a
added value in producing gloves and not just selling latex as raw material to
other countries.

26
Limits

A goal that was not included in this work is the analysis of the costs that
they would represent the assembly of an immersion line that proposes this design, this could
provide interested companies in developing an industry of this type with a broader vision
profound regarding the business, although due to it being a custom design, it is difficult to determine
market costs of the necessary equipment. To know production costs, one could
propose the specific raw materials for the mixture of vulcanizers, accelerators and
stabilizers, although due to the variety of chemical compounds that can be used
to perform these functions and the proportions of the same used in the formula for
the mixture, the same will not be specified.

27
2.6 CONTRIBUTION

The main contribution of this research is the creation of a team design for the
glove production, sizing of it depending on a rate of
production and size of gloves to be produced.

To the industries dedicated to the processing and export of latex in Guatemala, a

tool that increases the ability to diversify the marketing of latex that is
exports, offering products with higher added value.

To small business owners, a business option with a raw material that is extracted in
our country, which provides them with competitive advantages over industries that
they dedicate themselves to the production of gloves that they export to our country, since setting up a

companies dedicated to this activity can eliminate transportation costs and tariffs.

At the Rafael Landívar University, an article that serves as a useful tool for anyone
Guatemalan who wishes to set up a company. Likewise, it can serve as a document of
consultation for any student who wishes to undertake studies about both latex and
the production of gloves.

In Guatemala, the capacity to be one of the countries that have industries dedicated to
latex manufacturing, not only to export this raw material, thus giving it greater
added value to their export products.

28
 III. METHOD

3.1 SUBJECT

Unit of Analysis: Production process of gloves from natural latex.

Subject: Roberto Antonio Cahueque Acosta, who has 15 years of experience.

experience and published in the year 2008 the graduation work Evaluation of two
coagulant agents for natural latex in the manufacturing by immersion of type gloves
domestic.

3.2 INSTRUMENTS

Interview: An interview was conducted with Mr. Roberto Cahueque Acosta, from which
obtained general information about the industrial vulcanization process of
rubber. (See Annex No. 5)

Equipment to be used in the immersion line: Equipment will be included from which
obtained a quote since there are few suppliers in the market (See Annex
No. 3).

Ceramic Molds: For the glove production process, the mold can
can be made from different materials, although the preferred material is of the type
ceramic (See table 2, Critical Summary of the Theoretical Framework). A request was made for a

quotation for molds to the company CeramTec. For the production of gloves
domestic type, the recommended last sizes for the region
Central American are 7, 8, 9, and 10 (See Annex No. 5), which have a
length between 14 and 16 inches, and the base of the last measures 3.5 inches wide
for 4 inches in length. Below is an image of the lasts:

29
 Figure No. 5: Ceramic Molds

Source: Ceramtec (2,011)

Oven: A quote for an oven was requested from a company dedicated to the
manufacturing of ovens in Guatemala, which can be used for the process of
glove manufacturing, the specifications are as follows:
. Dimensions of the interior camera: 65" wide x 35" deep x 75" high.
. Semi-automatic convection oven.
. 2 insulated doors.
. Exterior and interior camera made of black sheet metal painted with oven paint.
. Temperature through 4 gas burners of 90 BTU per hour each (approximately).
. Temperature range 40º C to 120º C.
. Security alarm in case the flame fails.
. Programmable electronic temperature control. PID type.
. Stability of +/- 5 ºC.
. Internal airflow for uniform operation.
. 2 adjustable shelves.
. Walls insulated with fiberglass.
. 120 VAC voltage 7 Amp, 60 Hz.

30
 Figure No. 6: Convection Oven

Source: Metalab (2,011)

Electric Hoist: a quote was requested for a two-ton electric hoist

tons to a company in our country dedicated to the marketing of the
the same. And the following specifications were provided:
. Capacity: 2,000 kilos
. Chain Branches: 2
. Motor: 1.5 kW-0.37 kW
. High lifting speed: 4 meters per minute.
. Low lifting speed: 1 meter per minute.

31
Figure No. 7: Electric Hoist

Source: Solarsa (2011)

32
3.3 PROCEDURE

3.3.1 Equipment sizing

Block diagram for determining the dimensions of the equipment

Procedure Types of Variables

Determine Time Residence Time

Total Production Type: Intensive

Establish Number Production Rate

from Hormas by Plato Type: Intensive

Calculate Dimensions Number of Molds per Plate

from the Plate of Hormas Type: Extensive

Plate Dimensions Molds

Define Dimensions Type: Extensive
Immersion Tanks Size of Lasts
Type: Extensive

Specify Dimensions Immersion Tank Dimensions

Immersion Car Type: Extensive
Variable: Dimensions Plate Mold
Type: Extensive

Establish Dimensions Variable: Plate Molds Dimensions

Hornet Car Type: Extensive

Determine Dimensions Variable: Oven Car Dimensions

Oven Type: Extensive

33
3.4 DESIGN AND STATISTICAL METHODOLOGY

Not applicable because the objective of this work is the design of an immersion line.
for the production of gloves made from natural latex in Guatemala, so that it does not
apply a statistical method.

34
 IV. PRESENTATION AND ANALYSIS OF RESULTS

4.1 Dimensions of the Equipment

Table No. 3: Times by Workstations

Workstation Time Total operators required

minutes
Immersion Line 52.8 2
Oven 60
Source: Own elaboration (2011)

Table No. 4: Requirements and Dimensions of Form Plates

Construction Material Number of Molds Dimensions (Inches)

Steel 20 Long 28
Wide 28
Source: Own elaboration (2011)

Table No. 5: Dimensions of Tanks # 1, 2 and 5

Construction Material Dimensions (Inches)

Steel or Black Iron 454 High 24
Long 34
Width 34
Source: Own elaboration (2011)

35
Table No. 6: Dimensions of Tanks # 3 and 4

Construction Material Capacity (Liters) Dimensions (Inches)

Steel or Black Iron with 588 High 24
painting resistant a the Long 44
corrosion Width 34
Long Stirrer 20
Source: Own elaboration (2011)

Table No. 7: Dimensions of the Immersion Car

Construction Material Capacity Dimensions (Inches)

Steel 1 Plate of Hormas High 81
Large 77
Width 46
Source: Own elaboration (2011)

Table No. 8: Baking Cart Dimensions

Building Material Capacity Dimensions (Inches)

Steel or Black Iron 1 Plate of Shapes High 64
with resistant paint Long 60
heat Wide 30
Source: Own elaboration (2011)

36
Table No. 9: Dimensions of the Oven

Oven Parameters Dimensions (Inches)

Temperature 100-120 ºC High 75
Construction Material Steel wide 65
Capacity 6 Plates of Shapes Width 35
Source: Own preparation (2011)

37
4.2 Design of the Immersion Line for glove production

4.2.1 Complete Process Design

Complete Process

240

Hoist Output
Car of
Baking 60 inches
60"
Resting place

34"

6 inches Oven 65 inches

44"

6"
35 inches
Line of
44" Immersion

6 inches
Car of
Immersion
34" 229

6"

34"

3" 34" 3" 40 inches

80"
Resting place

Hoist
Demolding

36" 204

Source: Own elaboration (2011)

38
4.2.2 Design of the Immersion Line

4.2.2.1. Upper View

Immersion Line
(Upper View)

7 7

Parts of the Immersion Line:

5
Clearing Tank of Molds.
2. Hot Water Tank.
3. Coagulant Tank.
4. Latex Tank.
4 5. Hot Water Tank.
6. Dip Car
7. Rails for Immersion Cart.

Source: Self-made (2011)

39
 4.2.2.2. View Profile

Immersion Line
(View Profile)
8" 30" 8 inches

20"

16 inches

23"
24 inches Tank 1 Tank 2 Tank 3 Tank 4 Tank 5

8"
12"
10 inches
4" 4"

Source: Own elaboration (2011)

40
4.2.3 Design of the Immersion Cart

20"

Hoist Frame
Crank
16 inches
Mold Plates
Mold Plate

5"
Transfer Control of the
Car through the
Line
18 inches
Tank

8"

10"
Soil
4 inches

1"2" 34" 2" 1" 40"

Source: Own elaboration (2011)

41
4.2.4 Design of the Counter-Plate

34"

Support for hoist

Crank

12 inches Lever closure bars

4 inches

Bars that secure

plato

Source: Own elaboration (2011)

42
4.2.5 Design of the Molds Base and its Support

4.2.5.1 View of the Molds Position on the Plate

28

2" 3.5" 2" 3.5" 2" 3.5" 2" 3.5" 2" 3.5" 2"

2"

4 inches

2"

4"

28 2 inches

4"

2"

4"

2"

Source: Own creation (2011)

43
4.2.5.2 Frontal Upper View of the Molds Plate

28

2"
11 inches

28"
6 inches
24 inches

6 inches 6 inches 6" 6 inches

1 0.6 inches 0.6 inches 0.6" 1

Source: Own elaboration (2011)

4.2.5.3 Front View Mold Support

Mold Plate

Support Guide
Molds

2" Mold Support

Platinum (Mold Support)

1" 4" 1"

Glove Last

Source: Own creation (2,011)

44
4.2.5.4 Guide for Mold Support

28"

Source: Own elaboration (2011)

45
4.2.5.5 Upper View Support for Molds

6 inches

2"

4"

1"

4"

4"

4"

4"

2"

1 4" 1"
Source: Own elaboration (2011)

46
 4.2.5.6 Full View Support for Molds

6 inches

28 inches

4 inches

2"

4"

Source: Own elaboration (2011)

47
4.2.5.7 Platinum Design (Front View)

Screws

Platinum

Mold

Source: Own elaboration (2011)

48
4.2.6 Design of Tanks # 1, 2 and 5

34 inches

34"

24 inches

12"

Source: Own elaboration (2011)

49
4.2.7 Design of Tanks # 3 and 4
Reducer

Motor
Liquid Level

34

24 inches

34 inches 10"

Source: Own elaboration (2011)

50
 34" 10"

24 inches

12"

Source: Own elaboration (2011)

51
4.2.8 Design of the Baking Trolley

30 inches

4"
2"

20"

2"

20"

2"

20 inches

Source: Own preparation (2011)

52
 29" 2" 29"

4"
2"

20"

2"

20 inches

2"

20 inches

Source: Own elaboration (2011)

53
4.2.9 Design of the Plate Rest

29 2" 29"

2"

34"

Source: Own elaboration (2011)

54
4.2.10 Design of the Demolding and Exit Hoist

100"

Tires
Source: Own elaboration (2011)

55
4.3 Process Diagrams

4.3.1 Operations Diagram of the Process

Figure No. 8: Operations Diagram

Description Process: Manufacturing of Latex Gloves

Glove Production Process

Place the plate molds in

0.8 minutes 1 Immersion Car
EDTA

1.8 min 2 Tank 1 Immersion

Water

1.8 minutes 3 Tank 2 Immersion

Coagulant

0.6 min 4 Tank 3 immersion

Latex

0.5 min 5 Immersion in Tank 4

0.5 min 6 Turn Mold Plate

Latex Film Review

0.5 min 1 in Hormas

Water

1.8 min 7 Tank 5 Immersion

Transfer Plate from

0.5 min 8 Horn to Rest

Transfer Plate of
0.3 minutes 9 Horns to Hoist Exit

Dish Transfer
0.3 min 10 Horns to Car
Horny

60.0 min Glove Horn

11

0.5 min Glove Review

2 Vulcanization

2.0 min Demolding of Gloves

12

0.5 min Glove Review

3 Finished

56
Table No. 10: DOP Summary

EVENT NUMBER TIME

Operations 12 70.9 minutes
Inspection 3 1.5 minutes
Source: Own elaboration (2011)

57
 4.3.2 Flowchart of Operations of the Process

Table No. 11: Flow Diagram of Operations

Description of the Symbol Time Recommended Method

Activity (inch)
Place plate molds in 0.8 min 114 inchesUse the hoist of
immersion car Demolding
Immersion Tank 1 1.8 min 40"
Immersion Tank 2 1.8 min 50 inches
Immersion Tank 3 0.6 min 50 inches
Immersion Tank 4 0.5 minutes 40 inches
Turn Mold Plate 0.5 min 0”
Movie Review of 0.5 min 0”
Latex in Molds
Tank Immersion 5 1.8 min 0"
Transfer Plate of 0.5 min 0" Use Car
Forms to Rest Immersion
Plate Transfer 0.3 minutes 0” Use hoist to
Hoists to Pulley of lift plate of molds
exit of the rest stop
Transport Plate of 0.3 min 200" Slow transfer to
Take the area of the Car. avoid damage to the last
of Horneo
Transfer Plate of 0.3 min 0" Use hoist of
Legs to Car exit
Horneo
Car Transport 0.3 min 40 inchesTransfer not fast for
Oven to Oven avoid damage to the last
Glove Horn 60.0 min 0"
Glove Review 0.5 minutes 0"

58
Transport Car of 0.5 minutes 433 Use gloves since the
Horny to the Area of baking car
Demolding find hot
Molding of Gloves 2.0 min 0"
Glove Review 0.5 minutes 0"
Finished
Totals 12 3 0 3 0 73.5 967
Source: Own elaboration (2011)

Table No. 12: DFOP Summary

EVENT NUMBER TIME DISTANCE

Operations 12 70.9 minutes 294
Inspection 3 1.5 minutes 0"
Transport 3 1.1 minutes 673
Source: Self-made (2011)

59
4.3.3 Process Flow Diagram

Figure No. 9: Path Diagram

Hoist Exit Horny Car

1
9
10

8 Resting place 2

7 11

Oven
1
6
5

2
Line of
4 Immersion

Car of
Immersion

3
3

1 Resting place

Hoist
3 12
Demolding
Source: Own elaboration (2011)

60
4.4 Mass and Energy Balance of the Process

Figure No 10: Mass Balance

Source: Own elaboration (2011)

Table No. 13: Energy Balance

Heat Quantity Efficiency

Combustible 922614 kJ/day 85%
Increase temperature to boiling point (water) 5983 kJ/day
Phase change of water 46377 kJ/day
Temperature rise rubber 5586 kJ/day
Rubber vulcanization 726276 kJ/day
Source: Own elaboration (2,011)

61
 V. RESULTS DISCUSSION

5.1 Complete Description of the Immersion Line for Glove Production

5.1.1 Description of the Complete Process

The complete process of the immersion line is of a hybrid type (continuous and batch mixing)
batches), since the process involves immersing a plate of molds in 5 tanks
by means of a mobile cart, so each mold plate can be considered as a
batch. The process begins with the transfer of a plate of molds (molds with the shape of
one hand) to the mobile immersion cart, which is transferred with the help of the hoist of the
immersion cart from the rest area to the entrance of the line. The process that occurs in
the immersion line is described in the section on Design and Description of the line
immersion (section 5.1.2).

After the mold passes through the immersion line, it has a film of
latex on its surface (which will later form the glove), goes to the resting area of
plates, this done with the help of the mobile cart hoist. Subsequently, the plate
from the molds is transferred to the baking cart with the help of the exit hoist, which
enter the oven to carry out the drying and vulcanization process. After coming out
from the oven, the latex is completely dry and vulcanized.

The baking cart is taken to the demolding area, where the mold plates are
transferred to the demolding hoist. The demolding process is carried out with the help of
of the demolding hoist, the procedure consists of placing the mold plate to
a height at which the operator can easily remove the gloves, for then the
The dish with the molds, now without latex, is moved back to the entrance rest area.
so that it can be entered into the immersion line.

62
5.1.2 Description of the Immersion Line

The immersion line consists of a series of 5 tanks and a mobile immersion cart.
The 5 tanks are situated in series, this is to expedite the immersion in each of them.
tanks using equipment (mobile immersion vehicle) that fulfills this function. The
tanks number 3 and 4 have a design and size different from the other tanks, this is
due to the conditions required by the materials contained in these tanks
specific. As can be seen in the top view (See Line Design of
Immersion, Section 4.2.2), on each side of the tank line are located
rails, these make it possible for the mobile car to move along the entire line of
immersion. The process of the immersion line consists of, as its name indicates,
immersion of the mold plate in each of the tanks, each of them has
different materials (some considered as supplies and others as raw materials),
which serve a specific function within the process. The process of
The immersion of the mold plate is carried out by means of a movement device.
vertical located in the mobile cart, it will be described later in the
section of Description of the immersion cart, section 5.1.3.

Tank number 1, called Cleaning Tank for molds, contains a solution of

EDTA (considered as input), which can be handled at a temperature of
70 °Celsius, according to Barrios (2010). This tank has a simple rectangular shape, this
it is due to the fact that no specific condition is required for this material
(only the temperature). The purpose of immersing the molds in this
The tank is to carry out a general cleaning of the mold, eliminate heavy metals, and precipitate.
the compounds that make up hard water, according to Barrios (2010), as well as traces of
calcium compounds that can be formed by the addition of coagulant (added in the
tank 3). Traces of calcium compounds can form due to the film
the coagulant adheres to the mold before the latex film, so when performing the
de-molding of the already vulcanized latex, on the inner part (between the latex and the mold),
these traces of calcium compounds can form. The residence time in the
tank is 55 seconds, according to Cahueque (2008)

63
Tank number 2, called Water Tank, can be operated at a temperature in a
range between 60 °Celsius, according to Barrios (2010). The purpose of carrying out an immersion of
the molds in this tank is to carry out a general cleaning and completely remove
traces of the EDTA solution added to the previous tank, so that they do not affect
the action of the coagulant, which will be added in the next tank. This tank has
a simple rectangular shape, this is because no condition is required in
specific for this input (only the temperature). The immersion time in this
the tank is 55 seconds, according to Cahueque (2008)

Tank number 3, called Coagulant Tank, can use a solution.

calcium nitrate aqueous solution, in a concentration range between 15-40% as a coagulant,
the temperature of the solution is 30 °Celsius according to Cahueque (2008). The purpose of
immersing the molds in this tank is adding the compound that
will produce a coagulation of the latex molecules, causing them to
they will be agglomerated and will adhere to the mold, to be subsequently vulcanized. This
the tank has a design distinct from the previous tanks, this will be explained later.
The immersion time in the tank is 30 seconds, according to Cahueque (2,0010).
Heating of the solution will be carried out using a coil, since it is not
it requires a very high temperature, propane gas will be used as fuel.

Tank number 4, called Latex Tank, contains a solution made of latex and
a dispersion that contains a mixture of vulcanizers, accelerators, and other compounds
with different functions, which carry out the vulcanization reaction of the
latex molecules, in order to form the glove. (For a more detailed description of the
dispersion of vulcanizing agents see section Raw Materials, Section 1.2.9). The purpose
The purpose of immersing the molds in this tank is to form the latex film.
on top of the mold, this film is what will form the glove. The residence time in
this tank is 20 seconds, which depends on the gauge desired for the glove to
to manufacture.

Tank number 5, called Hot Water Tank, just like tank number 2,
It performs a cleaning function, which is intended for the outer part of the layer.
of latex. It is also desired to remove excess coagulant that may be

64
to be found in the molds. The water temperature should be 50 °Celsius and the time
the residence time is 90 seconds, according to Cahueque (2008). The design of the tank is the same as

design of the first 2 tanks, this is because no conditions are required

specifically for this input (only the temperature).

A more detailed description of the design of the tanks is provided below.

The design of these tanks differs from other tanks; it is rectangular with
a trapezoid at one of the ends. In the added space (trapezoid), a
agitator, which is used to give movement to the fluid. It can also be observed,
in the design of section 4.2.7, the tank has a false bottom, which serves to
control the regime of fluid movement and to retain clots (which can be
depending on the quality of the latex) and other contaminants (any residue
that could not have been removed in the previous tanks. It also meets the requirement to maintain
the homogeneous solution, and in the particular case of latex, to prevent the formation of a skin
on the surface of the product. The fluid movement regime must be laminar, since
that if it were turbulent, the latex or coagulant film added to the mold would not
It would be uniform, so the glove would have defects. The arrows that are observed in the
design (Section 4.2.7) indicate the direction of fluid flow, this is obtained thanks to
that the agitator creates a suction effect. It is also observed that this tank must
to be equipped with a motor, which is regulated with a speed reducer, in order to
to be able to control the speed of the agitator, so that the flow rate is maintained
laminar.

The 5 tanks must have mechanisms for controlling the temperature of the material
that contain, it must also have a mechanism so that the tanks can be
completely closed, so that when production stops at the end of a shift, it does not
contaminate the product.

65
5.1.3 Description of the Immersion Cart

The function of the immersion cart is to move the mold plate along the line of
immersion, so that the molds can be submerged in each of the tanks. The
The immersion car consists of a part in which there is a space intended for
operator, there is also a device for controlling the transfer of the
immersion carriage through the line, whose function is to control the movement
of the car through the rails, so the operator is able to control the position of the
mobile car through the immersion line.

The mobile cart also has an electric hoist (with its respective frame), the
its function is to control the height of the mold plate, so when it is found
mold plate on top of a tank, the operator can lower it through the hoist.
mold plate up to a height where immersion takes place and then raise it
mold plate to be able to move to the next tank. The winch is electric, so
the transfer height and the immersion height are controlled by the use of a
button to raise and lower the mold plate.

The hoist holds the backing plate of the mold plate, which serves the function of supporting.
the mold plate, the description of it will be provided in the section 'Description'
from the counter-plate, section 5.1.4. The counter-plate is attached to the hoist frame.
through concentric tubes, which serve as support for it; when raising the
against the plate, with the help of the hoist, the inner tube rises and the outer tube remains at
its position. The use of concentric tubes is important, as they prevent the counter-
plato, when rising or falling, has a vibrating movement, which would affect the final quality.
from the glove, since the formed film would not be completely uniform.

66
5.1.4 Description of the Counter-Dish

The counter-plate is a device that has various functions, which will be

described below. The underplate is divided into two parts, the support part for
the mold plate (bottom part), and the part that enables the movement for the plate
of molds (upper part). At the bottom of the counter-plate is the part that
supports the mold plate, it has a lever to control the
movement of two bars, which are used to secure the mold plate.

The upper part makes it possible for the mold plate to move, this part is
important because it is necessary to rotate the mold plate 180 degrees (to
either side), this is to avoid the drop effect. When taking out the molds
from the latex solution, there is an excess of solution on the tips of the fingers of the
horma, this excess is called the drop effect. This movement is performed with the
assistance from a crank, which is coupled to a bar that crosses the top
from the counter-plate, so the counter-plate can be rotated, and therefore, the mold plate.
With this movement, the excess at the tips of the fingers is eliminated, as
gravity, the excesses slide into the palm of the hand over the same film of
latex.

5.1.5 Description of the Mold Plate and its Support

Description of the Position of the Molds on the Plate

According to the sizing of the equipment (framework IV), each mold plate has
with 4 rows and 5 columns, which means the plate holds 20 molds. Each mold, in its
The bottom part is elliptical in shape, measuring 4 inches long by 3.5 inches.
inches wide. The molds will be described in the section 'Specifications of
the molds," section 5.1.10. Between each mold there is a space of 2 inches,
this space is sufficient for the worker to carry out the process of
demolding to remove the glove from the mold.

67
Description of the Upper Front Section of the Mold Plates

In the front top view of the mold plate (Section 4.2.5.2) you can
two handles can be observed, they serve as entry for the bars of
support of the counter-plate, with which the mold plate is secured. Likewise,
four guides can be observed, which correspond to each of the rows of
mold plates, these serve to support the mold holder, which
will be described later.

Description of the Front Section Mold Support

In the view of this section (Section 4.2.5.3), support can be observed for
molds, which is located within the guides found in the part
lower part of the mold plate, these guides are welded to the mold plate. The
the space between the guides is 6 inches (4 inches of the mold length and 2
extra inches of the mold support length). It is very important that the
mold support is adjusted in the guides, ensuring that there is no
vibration of the molds, as this would create defects in the glove. Also,
you can observe the plate, which secures the mold to the mold support; the
the description of it will be done later (section 5.1.5.7).

Description of the Guide for Mold Support

The mold support guide measures 28 inches long, the same length as
it has the mold plate. The guide is 1 inch wide, this space is
necessary for the mold support to enter.

Description of the Upper Section Mold Support

In the top view (Section 4.2.5.5), you can see the 5 plates that go in
Each of the rows, a mold is placed on each of them.

68
 they measure 4 inches long by 4 inches wide, this is due to
that the holders are a little longer than the molds.

Complete Section Description Support for Molds

In the view of the complete section (Section 4.2.5.6) it is observed more

detailed support for molds, at the top of it
they find 6 sheets, which serve as support in the guides of the plate of
molds, they must be made to measure to ensure that they
adjust in the guides and there is no vibration. The vertical sheets that can be seen
join the upper plates to the bases, these measure 2 inches in height. In the
At the bottom of the support are the plates, which serve as
mold grips, their description will be shown below.

Description of the Platina

In the design of the plate (Section 4.2.5.7) the shape can be observed.
platinum, its shape is due to the mold being hollow, so in the
the upper part has a space, in which the plate enters and is held
secured by means of a pair of screws.

5.1.6 Design and Description of the Baking Trolley

The baking cart is used to, as its name suggests, bake the glove, and for
So, to carry out the drying and vulcanization process. It has the capacity to
6 molds plates, which are received from the output hoist. As observed in
the design of the car is a skeleton, it has no walls, this is to facilitate the passage of air
through the molds, so all the molds will come into contact with the hot air
surrounding the inside of the oven. To ensure a continuous process, it is necessary to count
at least with 4 baking carts; one will be found inside the oven, another in the

69
 molding area, another in the output area of the tank line, and the last would be used
if there were any kind of problem with any of the cars.

5.1.7 Description of the Plate Rest

The dish rest is used to receive the molding plates from the tank line.
of immersion, as well as to receive the plate of molds after the demolding process,
these two processes are carried out with the help of the hoists. It is located in
a fixed position (both at the entry and exit of the immersion line) and its
The function is to streamline the process in the immersion line, as it is ready.
mold plate, the operator can move it at once to the rest and go for
a new plate of molds, so the process is not interrupted. It has a
capacity of two plates. Its design is the same as that of the baking cart, it is only a
skeleton.

5.1.8 Description of the Demolding and Exit Hoist

The hoist, both for demolding and for exit, must have a height of 100
inches, with this height it is sufficient to be able to take the plates from the molds
from the dish rack and place them in the baking carts. The
its operation is manual. The function of the output hoist is
Transfer the molded plates from the resting area to the baking cart. The function of
hoist, which is located in the demolding area, is to take the mold plates from the
baking cart and serve as support for the demolding process, to
subsequently place the plate on the rest at the entrance of the line. After this
process, the mold plate is ready to enter the immersion line again.

5.1.9 Construction Materials of the Equipment

For the construction of all the parts of the dish and the counter-dish of molds, including the
Platinum, high hardness steel should be used, this is to prevent the material from suffering.

70
 some deformation or breakage, causing a fall of the lasts and therefore the
breakage of the same. The construction material of the tanks must allow
easy cleaning and easy removal of rubber, must be corrosion resistant,
for which stainless steel is recommended, although they can be made of black iron.
(cheaper) and must have epoxy paint, its function is to serve as
protection system for iron, as it prevents corrosion in iron, which allows it
provide a long life to the tanks. The supports and the baking cart are
they can be made of black iron with epoxy paint, as they do not have contact with
no material from the process, they only serve as support. The baking cart is given
heat-resistant paint must be applied due to the baking process.

5.1.10 Specifications of the Lasts

Molds can be made of wood, metal, or ceramic, each material has its
advantages and disadvantages. The best option for the mold material is ceramic, already
that the wood deforms due to heat, so when placing the mold in the oven
It would deform; likewise, the cost of a metal mold compared to a mold
ceramic is taller. When using a ceramic mold, it must be handled with great care.
Caution, as if it falls to the ground it breaks, for the same reason, in the design of the
immersion line, various devices have been installed (electric hoist, support
for molds, spacers at the entrance and exit of the immersion line) to ensure
the mold.

Depending on the type of glove, the height of the mold varies, as well as their thickness, the
The design presented in this work is made for molds that have a height
between 14 and 16 inches, if the height is greater, modifications must be made in the
dimensions of the immersion line equipment.

71
 5.1.11 Specifications of the Oven

The type of oven that should be used in this process is convection, as the heat
it must be transferred to the latex film through hot air. The oven must
to have a maximum temperature limit of 120 °Celsius, since if the temperature is
above this value, the rubber degrades, so the glove produced does not have
optimal quality conditions. The oven must have an appropriate size so that
it should be able to fit the baking cart, and it shouldn't be too big to be usable
the least amount of energy to achieve the desired indoor temperature; therefore, the
the appropriate dimensions for the design proposed in this thesis are 75 inches high, 35
inches deep and 65 inches wide.

5.2 Material and Energy Balance

For the glove production process, an energy balance was carried out.
to determine the material requirements of the process, as well as of the
fuel necessary for the operation. The material balance was carried out only for
the solution of latex and chemical additives, since this solution is what will form the body of the
glove, the solutions found in the other tanks are considered inputs,
they only serve functions for the vulcanization of the latex-additive solution
the chemicals are suitable, likewise, the consumption of the other solutions is much lower.

The balances were determined based on the desired production rate for process 420.
pairs of gloves per day. As can be seen in figure no. 10, 53.58 are required.
liters of latex-chemical additive solution, so the tank has a sufficient size
(volume) in order to meet the daily raw material requirement. It should be taken
keep in mind that the tank should be filled as the level goes down, this for the purpose of
that the film formed in the mold always remains the same size, so it must
to have a continuous feed system to the tank, so barrels must be placed
or another type of storage container for raw materials next to the line of
immersion.

72
 It can be observed in Figure no. 10 that 20.43 kilograms of water evaporate per day, for
this data will be useful for the fuel calculation in the drying oven and
vulcanization, in which all this water evaporates.

When performing the energy balance, the goal is to determine the amount of fuel.
necessary for the operation of the oven. Since there is no data regarding the
thermal efficiency of the furnace, an 85% efficiency was assumed (since it is a furnace
new). It was determined that 19.32 kilograms of propane gas are required per day, as is
you can observe in table no. 13.

5.3 Process Diagrams

The process diagrams were created to have a deeper understanding of the process.
since the required times in production as well as the quantity can be determined
operations that must be performed during the process. The operations diagram was created
of the process, all operations and inspections were established in it (the
inspections are carried out to ensure that the film formed in the mold is free of
defects, as well as to separate the final product that is defective) that are taken to
During the process, 12 operations were recorded, lasting 70.9 minutes.
3 inspections lasting 1.5 minutes.

A flow diagram of operations was also created, with which the

total time of a cycle in the process, which has a value of 73.5 minutes, also
they determined the total number of operations, which is 18, including 3 operations of
transport, it establishes recommendations on how to carry out the
operations.

Finally, the flowchart of the process was created, which was established
only in the part of the plant where the line designed in this is located

73
work, other elements of the plant were not included, such as the raw material warehouse, since
this work was limited to the design of the production line.

74
 VI. CONCLUSIONS

1. The design of the immersion line consists of two divisions, the first division consists of the
immersion line, which begins the process of transferring the mold plate to the car of
immersion and concludes with the transfer of it to the output rest; the
the second division consists of the baking process, which starts from the transfer of the plate
of molds the baking cart and finishes with the demolding process.

2. According to the process diagrams (DOP, DFOP, Route Diagram), during the process
For glove production, there will be 3 inspection activities, 3 transportation activities, and 12.
operations; a total distance of 967 inches (24.6 meters) will be covered in a time
Total cycle of 73.5 minutes, with a total of 2 operators required.

The ideal number of molds that each plate should have is 20 molds.
that the dimensions of each immersion plate must be 28 inches long by 28
inches wide, in order to meet the desired production rate.

4. The dimensions of the immersion tanks are 34 inches long (tank #1, 2, and 5), 44
inches long (tank # 3 and 4), 34 inches wide (all tanks) and 24 inches
from above (all the tanks); with these dimensions the desired production rate is met
for the process.

5. The dimensions of the oven are 75 inches high, 65 inches long, and 35 inches wide.
wide, they were established according to the requirement that the free space be minimal (space
between the baking cart and the internal walls of the oven) so that the air volume
that must be heated as little as possible and the movement of entry and exit from the oven is
simple.

6. According to the mass and energy balance, the inputs to the process are 49.83 kilograms per day of
solution of latex-chemical additives, 19.32 kilograms per day of propane gas (fuel);
The outputs of the process are 20.43 kilograms per day of evaporated water and 29.4 kilograms
per day of gloves (840 gloves).

75
 VII. RECOMMENDATIONS

1. Conduct a market study about gloves in the Central American region, in order to
determine the existing demand and supply in this market, the prices handled by the
current competition and the marketing channels that can be used, this for the purpose of
to establish whether there is a viable market for this product in that region.

2. Conduct an economic study of the glove production process proposed in this.

work, in order to determine the operating costs, the type of investment that must be made,
the required working capital, the break-even point, and the cash flow that will be obtained,
this in order to verify if the process is cost-effective, presenting a
acceptable utility.

3. Perform a financial analysis of the proposed glove production process in this.

work, to be able to determine the net present value and the internal rate of return of this
business, as well as carry out a sensitivity analysis regarding these variables, for
evaluate the long-term profitability and risk of this operation.

4. Conduct a study on the ideal composition of the latex-chemical additives mixture.

(vulcanizing agents, stabilizers, accelerators, antioxidants, activators) that provide the
highest quality in the final product (glove), due to the fact that in this work only
they mentioned the names of some of the chemical compounds that can be used.

5. Since this work only designed the production line, it is recommended to

implementation, in a later study, of the complete plant design, taking into account the
regulations (environmental, industrial safety, hygiene) that must be complied with in it and
all services and auxiliary equipment that are needed, this in order to offer a vision
more extensive about the functioning of the process.

6. Conduct a study on the operating ranges of the process variables

production of gloves that provide the highest quality in the final product, among the

76
which can be mentioned immersion time in each of the tanks and temperature of
the solutions in the immersion tanks and the furnace.

77
 VIII. BIBLIOGRAPHIC REFERENCES

Baasel, W. (1990). Preliminary chemical engineering plant design. (2nd edition) The
Servier Editorial. United States.
2. Barrios, M. (2010). Determination of the percentage of solids, pH, and residence time
NBR latex optimums to obtain the standard gauge in nitrile gloves. Unpublished thesis.
Rafael Landívar University.
3. Cahueque, R. (2008). Evaluation of two coagulant agents for natural latex, in the
Immersion manufacturing of household-type gloves. Unpublished thesis. San University
Carlos from Guatemala.
4. Helmus, F. (2005). Process Plant Design. Wiley-VCH Editorial. United States.
First edition.
5. Hernandez, L. (2009). Feasibility study for the production and export of
Hule in Guatemala. Unpublished thesis. Rafael Landívar University.
6. McGraw Hill (2011). Illustrated McGraw Hill Encyclopedia Dictionary. (3rd Edition).
Mexico.
7. Morales, H. (2008). Pre-Feasibility Study for the Installation of a Plant
Beneficiary of Natural Rubber. Unpublished thesis. Rafael Landívar University.
8. Smith, et al (2003): Introduction to Thermodynamics in Chemical Engineering. (6th)
Edition). Mexico.
9. Rafael Landívar University (2009). Guide to Completing the Graduation Project. (1st.
Edition) Guatemala.
10. Velasquez, C. (2007). Determination of production, dry rubber content,
diagnosis of latex and plasticity in 25 clones of hevea brasiliensis (euphorbiaceae) in
Santa Ana Mixpiya Farm, San Miguel Panan, Suchitepequez. Unpublished thesis. University
Rafael Landívar.
11. Walas, S. (1990). Chemical Process Equipment, Selection and Design. Butterworth-
Heinemann Editorial. United States. First edition.

78
NETWORK SOURCES
1. Bank of Guatemala (2,011): CIF value of imports and FOB value of
exports by product of the agricultural, extractive, and manufacturing industries;
Consulted in internet he 01/10/2011 12:00 hours en:
Invalid input. Please provide a text to be translated.
001.htm&e=52791
Studies in the Vulcanization of Rubber, Thermochemistry of Vulcanization
of Rubber; Consulted online on 01/10/2011; 12:00 hours at:
Unable to process the request as the provided text is a URL and not translatable text.
3. CERAMTEC (2,011): Dipping Formers for safe handling, Consulted on the Internet on
01/09/2011, 14:00 hours in:
http://www.ceramtec.com/index/products/glove_dipping_formers/01077,0141,0426,0732
.php
4. Grupo Entre Ríos; Natural Rubber in Guatemala; Consulted online on 01/10/2011;
1:00 PM in:
The provided text is a URL and does not contain translatable text.
=130&lang=en
5. INSIVUMEH: Annual and monthly averages of atmospheric pressure, Consulted at
internet on 01/10/2011, 11:00 hours at: http://www.insivumeh.gob.gt
6. Urías Gamarro: Rubber exports increased by 70% in 2010; Consulted in
Internet on 09/04/2011, 3:00 PM at:
Unable to translate, as the provided text is a URL.
increased_0_448155196.html
7. University of Las Palmas de Gran Canaria: Thermal Conductivity and Density,
Consulted in internet the 05/09/2011 11:00 hours translatedText
http://editorial.cda.ulpgc.es/ftp/icaro/Anexos/2-%20HEAT/4-
Construction/C.6.4 Thermal conductivity and density.PDF
8. Pedro Luis Gallo National University: Characteristics of LPG; Peru; Consulted in
internet on 01/10/2011, 12:00 hours at:
http://www.unprg.edu.pe/bounprg/blogs/media/blogs/rsamillanri/DMecanico/simbologia.
pdf

79
QUOTATION
1. Metalab (2,011): Quotation for Convection Oven. Guatemala.
2. Solarsa, S.A. (2,011): Electric Hoist Quotation. Guatemala.

80
IX. ANNEXES

9.1 Calculations for setting the dimensions of the equipment

The establishment of the equipment dimensions is based on the production rate.

desired per day, as well as in the size of the glove that is desired to be manufactured. Depending on the

The two previously mentioned variables establish the dimensions of the plates.
molds of the immersion line, since the number of molds placed is determined in
each of these dishes. After establishing the dimensions of the dishes, the process moves on to
dimension the immersion tanks, the immersion cart, the supports, the carts of
baking and the oven. It is designed this way because the production process (times
of residence in immersion tanks and oven of the gloves) has times
established, so the dimensions of the equipment depend on the variables
initially mentioned. All these dimensions are displayed in the design of each one of
the immersion line components for glove production.

9.1.1 Establishing total time on the glove production line, according to the flow of
operation on it.

The total time on the production line is the time that elapses to fulfill a
cycle. A cycle refers to the moment when a plate of molds enters the line of
immersion, until this same dish comes out of the demolding process, to
again enter the immersion line. In the production line you can
classify two types of processes, the first is the immersion line process, the
second is the oven process (includes the demolding process), which includes
all the movements of the plate rest and the baking cart; this
classification is based on the fact that each type of operation is performed by an operator

different (in the case of baking, the process is automatic, so it does not require that
a worker is in this area all the time), so each operation does not
interferes with the others. The immersion line process takes 8.8 minutes (see
operations diagram, Frame IV) for each batch of molds, which includes from
the moment the mold plate is placed on the immersion cart until the

81
 the same plate is placed on the rest. In order to fill the baking cart, it
They need 6 dishes, so a total of 52.8 minutes are required. The transportation of the
plates of molds towards the baking cart are carried out at the same time as they are taken to
the process in the immersion line is completed, so no time is added to the
immersion line time. The baking time is 60 minutes, the subsequent
transport to the demolding area and the demolding operation are carried out
for 3 minutes, so the total cycle time is 115.8 minutes.

9.1.2 Establish the bottleneck of the entire process by comparing the times
required both in the immersion line and in the oven.

The operation is continuous, so during the baking time, it

will be working simultaneously on the immersion line. It is also important
mention that the transportation and demolding processes will be carried out simultaneously
to the two previously mentioned processes (oven and immersion line). It is
It is necessary to determine the bottleneck for the operation, in order to establish the
necessary dimensions according to the desired production rate. The total time for
producing 6 trays of molds (with already formed latex film) takes 52.8 minutes and the
the total baking time is 60 minutes, so the process in the oven is the
bottleneck.

9.1.3 Calculate the dimensions of the mold plate, according to the number of molds required.
on each plate, in order to meet the established production rate.

Next, an analysis will be made of the number of lasts needed in each

plate, depending on the desired glove production rate per day:

Process constants:

Desired production rate: 420 pairs per day.

82
 Working hours per day: 7 hours (the shift is daytime, so it is 9 hours)
workdays to date, including 1 hour for lunch and 1 hour for cleaning and
maintenance up to date).
Estimated residence time for each dish in the immersion line: 8 minutes
Take into account from the moment a dish enters the immersion line.
until he is taken to the baking cart).
Estimated cooking time for each dish in the oven: 1 hour.

The baking cart has a capacity of 6 trays, so 6 trays are

They will find 1 hour in the oven. Likewise, according to the estimated residence time by
each dish in the immersion line, completing the capacity of the baking cart takes
48 minutes, so the limiting step for production is the baking of the
gloves.

Starting the analysis from the production rate, the quantity of gloves will be determined.
what is required for each mold:

Once the number of molds per plate (20) has been established, the process of establishing the ...

dimensions of the plates. The plates will contain 4 rows and 5 columns, with a space
between 2-inch lasts. The dimensions of the lasts are 3.4 inches wide
by 4 inches long, so the dimensions of the plate will be 28 inches of
long by 28 inches wide, so the plate will be square.

83
9.1.4 Establish the dimensions of the immersion tanks, based on the dimensions of
the immersion plates and the size of the lasts.

The dimensions of immersion tanks # 1, 2, and 5 are established below,

this is also done according to the size of the last to be used (14-16 inches of
high) and to the dimensions of the mold plate (28"x28"). The height of the tanks will be
24 inches high, 34 inches wide, and 34 inches long, these
dimensions are set according to the existence of a space to avoid collisions between the
hormas and the tank.

For tanks #3 and 4, which must have space to place a mixer, the
the length is the only one of the dimensions that changes, it increases by 10
inches.

9.1.5 Establish the dimensions of the baking cart and the oven, based on the
dimensions of the immersion tanks and the mold plates.

The baking cart capacity of 6 trays (3 rows and 2 columns) is based on the
dimensions of the glove size are established according to the operator
it should be able to handle it well, which is why the car should not be too wide
neither very tall. The height of the baking cart is 64 inches (1.65 meters), so that
the cart is indeed manageable for the operator, as it is not too high. The cart of
baked measures 60 inches long by 30 inches wide.

The dimensions of the oven are determined by the dimensions of the cart.
baked, dimensions are established according to the free space between the cart of
baking and the walls of the oven are minimal, although spaces are left for the
baking cart can be easily moved when being entered and exited from the
oven. So the dimensions of the oven are 75 inches tall, 65 inches wide
long by 35 inches wide.

84
9.2 Mass and Energy Balance Calculations

The objective of performing the material and energy balance is to determine the amount of matter.
necessary supplies for each day of production, as well as the energy consumption that will be required
to carry out the operation.

For the realization of the material and energy balance in the glove manufacturing process.
The following considerations must be taken into account:

Only one of the five materials that are added to the mold, for the formation of the
movie, is taken into account as raw material for the glove, the other 4 materials
are considered as supplies, since they do not contribute to mass
significant to the final glove.
The only material considered as raw material in this process is the
solution that contains latex and the mixture of vulcanizing agents, which is added to the
tank # 4.

A material and energy balance will be performed for the baking process, from this balance it
you will obtain the necessary amount of raw materials and energy to be able to meet the rate of
desired production.

Below is the diagram of the baking process, which will serve as the basis for
the balance of matter and energy:

85
Figure No. 11: Baking Process Diagram

9.2.1 Mass Balance

The solution containing latex and the mixture of vulcanizing agents has 59% solids,
all the water is evaporated in the baking process (drying and vulcanization), so
that the final glove is made up solely of solids (latex and
vulcanizers) vulcanized. The weight of each glove varies between 30-35 grams, for which
which has an average of 32.5 grams. The maximum value of the range will be used for
the mass balance calculations, as the result is based on the amount.
necessary maximum.

Solid Balance:

()

( )

86
Therefore, 0.0593 kilograms of solution L1 are needed to produce 1 glove.
the desired production rate is 420 pairs of gloves (840 gloves) per day, therefore
what is needed is the following amount of solution L1 to meet this rate of
production

The density of the latex solution and vulcanizing agents is 0.93 kilograms per liter.
(data obtained from the interview with Engineer Roberto Cahueque Acosta, See
Annex 5), so the volume of solution needed per day is as follows:

The volume of the tank in which the latex solution and vulcanizing agents are contained is
approximately 450 liters, so the tank does have the capacity for one day
of production. There must be a continuous supply to the tank, as the level
it must remain constant in the tank so that the glove always comes out the same
size.

The amount of water that evaporates per glove is as follows:

()

( )

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9.2.2 Energy Balance

The amount of heat entering the system will be used for two processes, the process
of drying and the vulcanization process. For the process, heat must be applied with
the following objectives:

Increase the water temperature to the boiling point.

Evaporate the water.
Increase the temperature of the rubber to the vulcanization temperature
120 degrees Celsius
Vulcanize the rubber.

The following nomenclature will be used for the heat balance:

QA1Heat used to raise the temperature of the water from room temperature to
boiling point.
QA2Heat used for the phase change of water.
QG1Heat used to raise the temperature of the rubber.
QVVulcanization heat of rubber.
QCHeat provided by the fuel.
The balance will be done for one glove and subsequently it will be done for one day of
production.

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Table No. 14: Data for energy balance resolution

Date Quantity
Heat Capacity at Constant Pressure of 4.184
Water
Heat Capacity at Constant Pressure of 2.00
Rubber
Enthalpy of Evaporation of Water 2,270.2

Combustion Heat of Propane Gas 46,350

Specific heat of vulcanization 24,703

Source: Smith, et al. (2003).

Next, the heat will be obtained to heat the water from 25 degrees Celsius to
the evaporation temperature of water. The evaporation temperature is calculated
of water based on the pressure of our country (capital area), according to
INSIVUMEH, the pressure in Guatemala is approximately 640 millimeters of
mercury (85 kilopascals). Therefore, the evaporation temperature of water at this
the pressure is 95 degrees Celsius, according to Smith et al. (2003).

( ) ( )

89
Next, we will calculate the heat necessary to evaporate the water from the glove.
According to the data from the steam tables (Smith, 2003), the value of the enthalpy of
the evaporation of water is 2270.2 kJ/Kg, under the established conditions
previously.

( )

Next, the heat necessary to raise the temperature of the rubber will be calculated,
the specific heat capacity at constant pressure of rubber will be used for it,
using the same equation used to calculate the heat required to raise the
water temperature up to the boiling point:

( ) ( )

Next, the heat necessary for vulcanization will be calculated, a will be used.
specific vulcanization heat:

( )

The heat balance is shown below:

90
Data regarding the thermal efficiency of the oven was not provided, therefore
It is assumed that the efficiency of the oven is 85% (New oven)

Next, the amount of fuel required for the operation is calculated.

the oven works with propane gas as fuel, according to the manufacturer. The power
The calorific value of propane is 46,350 kilo-Joules per kilogram.

The fuel obtained earlier is the one needed to produce 1

glove, so the daily fuel consumption will be calculated below.

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9.3 Oven Quotation

92
9.4 Electric Hoist Quotation

93
Table No. 15: Specifications Hoist

Date
Capacity 0.5-2 tons
Standard elevations of 10, 15, and 20 feet
Speeds of 8 to 32 feet per minute
Rigid hook suspension
For medium or light-heavy usage applications
Source: Solarsa (2011).

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9.5 Interview Format Engineer Roberto Cahueque Acosta

Proposed questions:

1. What is the process of glove production?

What type of latex (natural or synthetic) is the most suitable for the production process?
household type gloves?
3. What are the most important operating conditions in production?
natural latex gloves?
4. Are there any specific conditions for handling latex within a line of
glove production?
5. What are the operations with the highest risk of defect creation in the
final product?
What actions are taken during glove production to prevent the creation
of defects in the final product?
7. What types of materials can be used for the construction of the equipment within
the immersion line?
8. What special considerations should be taken into account for the materials?
manufacturing of equipment within the immersion line?
9. What kind of care should be taken into account for the handling of the last within the
immersion line?
10. Is it possible to carry out the drying and baking operation of the latex film in a
same oven?
11. What are the relevant characteristics of the latex solution and vulcanizing agents for
to be able to perform a mass and energy balance?
12. What is the preferred size of the last for glove production? Taking into account
It states that the Central American region is the target market.

95