CHAPTER 3:

MILK Production Department

About the department:
The milk production department is the part of Jawad Food Company for Dairy and
Food, it consists of process suction, filling and packaging suction, incubation,
refrigerator.
There are two milk filling machines

Milk production processes

steps for preparing the milk solution in the production department of the factory:
1) Bring in the raw materials consisting of milk powder and other homogenizing
materials
2) Mixing the solids in the mixing tanks in a concentrated manner (70 degrees
Celsius), then stopping for 10-to-15 minutes (interlock).
3) Add oil at a temperature of 40 degrees Celsius, then rotate for 5 minutes.
4) The milk pasteurization process begins at a temperature of 85 degrees Celsius.
5) Pasteurization steps:
a. The temperature is raised to 90 degrees Celsius
b. Then it goes through the Holden stage
c. Homogenization
d. Vacuum
e. Cooling
f. Then it is sent to storage tanks
 6) It is cooled to less than 10 degrees Celsius
7) A sample is taken to the laboratory and then modified.
8) After approval from the laboratory and making the final modification, then
confirmation.
9) The withdrawal takes place to the production machines
FLOW DIAGRAM OF PANEER MANUFACTURING

Bring in the raw materials consisting of milk powder and other homogenizing
materials

Mixing the solids in the mixing tanks in a concentrated manner (70 degrees Celsius),
then stopping for 10-to-15 minutes (interlock).

Add oil at a temperature of 40 degrees Celsius, then rotate for 5 minutes.

The milk pasteurization process begins at a temperature of 85 degrees Celsius.

Pasteurization steps:
a. The temperature is raised to 90 degrees Celsius
b. Then it goes through the Holden stage
c. Homogenization
d. Vacuum
e. Cooling
f. Then it is sent to storage tanks

It is cooled to less than 10 degrees Celsius

 A sample is taken to the laboratory and then modified.

After approval from the laboratory and making the final modification, then
confirmation.

The withdrawal takes place to the production machines

Packing of packets through filling machine

Dispatch in insulated product for local sale or Refrigerated product for distant place
sale
The pre-sterilization involves:

• Hot water sterilization at the same temperature as the product shall undergo.
Minimum time of the hot water sterilization is 30 minutes from the moment the
relevant temperature has been reached in the whole aseptic part of the plant.
• Cooling the plant to conditions required for production.

Standardization:

The purpose of standardization is to give the milk a defined, guaranteed fat content.
The level varies considerably from one country to another. Common values are 1.5%
for low-fat milk and 3% for regular-grade milk, but fat contents as low as 0.1 and 0.5
% also occur. The fat is a very important economic factor”.
Pasteurization

Along with correct cooling, pasteurization is one of the most important processes in the
treatment of milk. If carried out correctly, these processes will supply milk with longer
shelf life. Temperature and pasteurization time are very important factors which must
be specified precisely in relation to the quality of the milk and its shelf-life
requirements, etc. The pasteurization temperature for homogenized, HTST pasteurized,
regular-grade milk is usually 72 – 75°C for 15 – 20 sec. The pasteurization process
may vary from one country to another according to national legislation. A common
requirement in all countries is that the heat treatment must guarantee the destruction of
unwanted microorganisms and of all pathogenic bacteria without the product being
damaged.

Homogenization

The purpose of homogenization is to disintegrate or finely distribute the fat globules in

the milk in order to reduce creaming. Homogenization may be total or partial. Partial
homogenization is a more economical solution, because a smaller homogenizer can be
used.
 Aseptic tank

The aseptic tank, in figure 6., is used for intermediate

storage of UHT treated dairy products.
Product flow and service media connections are shown in
figure 7.
It can be used in different ways in UHT lines, depending
on plant design
and the capacities of the various units in the process and
packaging lines.
Two examples are shown in figures 8.and 9.
• If one of the packaging machines incidentally stops the
aseptic tank take care of the surplus product during the
stoppage.
• Simultaneous packaging of two products.
The aseptic tank is first filled with one product, sufficient
to last for a full shift of packaging. Then the UHT plant is Figure 6.Aseptic tank with
switched over to another product which is packed directly accessories.
in the line of packaging machines. One or more aseptic
tanks included in the production line thus
offer flexibility in production planning.

Figure8.Aseptic tank used as a buffer for packing

one product

Figure 7 Product flow and service media

connections.
Intermediate storage tanks:

These tanks are used to store a product for a short

time before it continues along the line. They are
used for buffer storage, to level out variations in
flow. After heat treatment and cooling, the milk is
pumped to a buffer tank, and from there to filling.
If filling is interrupted, the processed milk is
buffered in the tank until operation can be resumed.
Similarly, milk from this tank can be used during a
temporary processing stoppage. In storage tanks,
figure 6, with a capacity of 1 000 to 50 000 liters the
inner shell is of stainless steel. The tank is insulated to Figure 1Intermediate storage
maintain a constant product temperature. In this case the tanks
outer shell is also of stainless steel and there is a layer of mineral wool between the
shells. The storage tank has an agitator and can be fitted with various components and
systems for cleaning and for control of level and temperature. This equipment is
basically the same as previously described for silo tanks. A good general assumption is
that the process requires a buffer capacity corresponding to a maximum of 1.5 hours’
normal operation, i.e. 1.5 x 20 000 = 30 000 liters.

Mixing tanks:

As the name implies, these tanks, figure 6.9.4, are used for
mixing different products and for the admixture of ingredients
to the product. The tanks may be of the insulated type or have
a single stainless-steel shell. Equipment for temperature
control may also be fitted. Insulated tanks, with mineral wool
between the inner and outer shells, have a jacket outside the
inner shell through which a heating/cooling medium is
pumped. The jacket consists of welded-on channels.
Agitators for mixing tanks are designed to suit the specific
application.
Figure 2Mixing tanks
Process tanks

In these tanks, figure 6.9.5, the product is treated

for the purpose of changing its properties. They are
widely used in dairies, e.g. ripening tanks for butter
cream and for cultured products such as yoghurt,
crystallization tanks for whipping cream, and tanks
for preparing starter cultures. There are many
different types of process tanks. The application
determines the design. Common features are some
forms of agitator and temperature control. They
have stainless steel shells, with or without
insulation. Monitoring and control equipment may
also be fitted. Figure 3Process tanks

Balance tank

There are a number of problems associated

with the transport of the product through the
line:
• The product handled must be free from air or
other gases if a centrifugal pump is to function
properly.
• To avoid cavitation, the pressure at all points in
the pump inlet must be higher than the vapor
pressure of the liquid.
• A valve must be actuated to redirect the
untreated liquid, should the temperature of a heat-
treated product drop below the required value.
• The pressure on the suction side of the pump
must be kept constant to ensure a uniform flow in the line.
Figure 00 Balance tank for constant inlet
These problems, as well as some others dealt pressure to the pump.
with here, are often resolved by fitting a balance
tank in the line on the suction side of the pump.
The balance tank keeps the product at a constant level above the pump inlet. In other
words, the head on the suction side is kept constant. The tank in figure 6.8.6 contains a
float connected by a lever to an eccentrically pivoted roller that operates the inlet valve
on the tank. As the float moves downwards or upwards with the liquid level, the valve
is opened and closed respectively. If the pump draws more from the tank than flows in
at the inlet, the level drops and the float with it.
The valve opens and lets in more liquid. In this way, the liquid in the tank is kept at a
constant level. The inlet is located at the bottom of the tank so that the liquid enters
below the surface.
Consequently, there is no splashing and, above all, no aeration. Any air already present
in the product on entry will rise in the tank. Some deaeration takes place. This has a
favorable effect on the operation of the pump, and the product is treated more gently.
The balance tank is often included in a recirculating system where liquid is returned for
recycling, e.g. as a result of insufficient heat treatment. In this case a temperature
indicator actuates a flow diversion valve which directs the product back to the balance
tank. This causes a quick increase in the liquid level and an equally quick movement of
the float mechanism to close the inlet valve. The product then circulates until the fault
has been repaired or the plant is shut down for adjustment. A similar procedure is
employed for circulating cleaning solution when the line is cleaned.

UHT treatment:

In a modern UHT plant, the milk is pumped through a closed system. On the way it is
preheated, highly heat treated, homogenized, cooled and packed aseptically. Low-acid
(pH above 4.5 – for milk more than pH 6.5) liquid products are usually treated at 135 –
150°C for a few seconds, by either indirect heating, direct steam injection or infusion.
High-acid (pH below 4.5) products such as juice are normally heated at 90 – 95°C for
15 – 30 seconds. All parts of the system downstream of the actual highly heating
section are of aseptic design to eliminate the risk of reinfection. Compared with
traditional sterilization in hydrostatic towers, UHT treatment of milk saves time, labor,
energy and space. UHT is a high-speed process and has much less effect on the flavor
of the milk. However, regular consumers of autoclave-sterilized milk are accustomed
to its “cooked” or caramel flavor and may find the UHT-treated product “tasteless”.
 Figure3 Tetra pak aseptic UHT treatment system
The UHT processes :
UHT is a technique for preserving liquid food products by exposing them to brief,
intensive heating. This treatment destroys the micro-organisms in the product. This
applies only as long as the product remains under aseptic conditions, so it is necessary
to prevent reinfection by packaging the product in previously sterilized packaging
materials under aseptic conditions after heat treatment. Any intermediate storage
between treatment and packaging must take place under aseptic.

Direct UHT plant based on steam injection and plate heat exchanger
In the flowchart in figure 5.
product at about 4°C is supplied from the balance tank (1) and forwarded by the feed
pump (2) to the preheating section of the plate heat exchanger (3). After preheating to
approximately 80°C the product pressure is increased by the pump (4) to about 4 bar
and the product then continues to the ring nozzle steam injector (5). The steam injected
into the product instantly raises the product temperature to about 140°C (the pressure
of 4 bar prevents the product from boiling). The product is held at UHT temperature in
the holding tube
(6) for a few seconds before it is flash cooled. Flash cooling takes place in the
condenser-equipped expansion chamber
(7) in which a partial vacuum is maintained by a pump
(8). The vacuum is controlled so that the amount of vapor flashed off from the product
equals the amount of steam previously injected. A centrifugal pump
Figure 5.Direct UHT plant based on steam injection and plate heat exchanger

(9) feeds the UHT treated product to the aseptic two-stage homogenizer
(10). After homogenization the product is cooled to approximately 20°C in the plate
heat exchanger (3) and then continues directly to an aseptic filling machine or to an
aseptic tank for intermediate storage before being packed.
The cooling water used for condensation is routed from the balance tank (1b) and after
leaving the expansion chamber (7) it is utilized as pre-heating medium after having
passed a steam injector.
At pre-heating the water temperature drops to about 11°C; it can thus be used as
coolant for the product coming from the homogenizer. In case of temperature drop
during production the product is diverted into a reject tank after additional cooling.
Simultaneously the plant is flushed by water. Following rinsing with water the plant is
cleaned (CIP) and sterilized before restart. Plants with capacities of 2 000 – 30 000 l/ h
are available.
  Problems faced by engineers
1) Milk tubes

2) pump problems
Suction line
The pump should be installed as close as possible to the tank or other source from
which the liquid is to be pumped, and with as few bends and valves as possible in the
suction line. This should have a large diameter in order to reduce the risk of cavitation.
Delivery line
Any throttling valve must be fitted in the delivery line, possibly together with a check
valve. The throttling valve is used to adjust the flow rate of the pump. The check valve
protects the pump from water hammer and prevents liquid from flowing back when the
pump has stopped. The normal place for the check valve is between the pump and the
throttling valve.
Cavitation
Cavitation can be detected by a crackling sound in the pump. It occurs when the
pressure drops locally below the vapour pressure and small vapour bubbles form in the
liquid. The pressure increases as the liquid continues further into the impeller, and the
vapour condenses very rapidly. The vapour bubbles collapse at a very high velocity and
at a local pressure which can be as high as 100,000 bar. This is repeated with a high
frequency and can cause pitting damage to the surrounding material, particularly if it is
brittle. Cavitation occurs when the pressure in the suction line is too low relative to the
vapour pressure of the pumped liquid.
How to avoid cavitation The general rule of thumb is:
a. Low pressure drop in the suction line (large pipe diameter, short suction
pipe, few valves, few bends, etc.)
b. High inlet pressure to the pump, for example a high liquid level above the
pump
c. Low liquid temperature

Milk filling and package suctions:

FILLING AND PACKAGING MACHINES FOR MILK:
 Heating chamber

Housing for electronics

Operating panel

Package formation

LS-element
Material roll

Figure 3.1 a Picture of the Tetra Pak A1 machine and highlighted parts.

Description
This is a Used Tetra Pak TBA/A1
Prisma 250 Sq Aseptic Filler which consists of a Tetra Pak TBA/A1 Aseptic Filler,
P70 Cardboard Packer and interconnecting conveyor.

Features
Manufacturer: Tetra Pak
Model: TBA/ A1 Prisma 250 Sq
Function: Aseptic filling and packaging line
Year of manufacture: 2018
Capacity: 3000 pcs / per hour
Working hours: 8370
Electrics: 400V / 50Hz / 3 Phase
Format: 250ml (Prisma)
Includes documentation (IM, MM, EM, OM)
Includes
TBA/A1:

Manufacturer: Tetra Pak

Model: TBA/A1 Tetra Prisma 250 Sq
Drawing spec: 648160-0100
Machine number: 21193-83939
Year of manufacture: 2001
Version: 010V
Conveyor:

Manufacturer: Tetra Pak

Year of manufacture: 2000
Cardboard Packer 70:

Manufacturer: Tetra Pak

Model: Cardboard Packer 70
Drawing spec: 670272-1100
Serial number: 75648/01546
Year of manufacture: 2007

About the Machin:

The Form Fill Seal(FFS) machines are a genre of filling equipment that can fill in a
flexible packing material. The product should be free flowing type, either liquid or
even granular. The equipment may be controlled electro-pneumatically or
mechanically.
A milk filling machine is a specialized piece of equipment used to fill milk into
containers such as cups, bottles, or pouches. The machine operates by filling the
containers with a precise amount of milk and sealing them for storage and distribution.
The Tetra Pak A1 is a type of filling machine designed for packaging products such as
milk, juice, and other beverages in Tetra Pak cartons. It is a highly automated machine
that can handle a wide range of filling volumes and speeds, making it suitable for both
small and large-scale production.
The Tetra Pak A1 filling machine uses a combination of mechanical and electronic
components to accurately fill and seal the cartons. The machine is designed to
minimize product waste and ensure that the cartons are filled to the correct level, with
a high level of precision and consistency.
Components of the machine:
The Tetra Pak A1 filling machine is a complex piece of equipment that combines
mechanical, electrical, and automation components to efficiently fill and package
products in Tetra Pak cartons. Here is an overview of the main working and
components of the Tetra Pak A1:
1. Carton magazine: The carton magazine is where the flat, pre-printed cartons are
stored before they are fed into the filling machine.

2. Carton feeder: The carton feeder is responsible for pulling the cartons from the
magazine and feeding them into the filling machine.
3. Filling system: The filling system is where the product is measured and
dispensed into the cartons. The Tetra Pak A1 uses a volumetric filling system,
which measures the exact amount of product to be filled into each carton.
4. Sealing system: The sealing system of the Tetra Pak A1 uses heat and pressure
to seal the cartons once they have been filled with the product. The machine can
also apply a plastic screw cap or a straw applicator to the cartons if required.
 5. Conveyor system: The conveyor system moves the filled and sealed cartons
through the machine and out to the packaging area.

6. Control system: The control system of the Tetra Pak A1 is responsible for
managing and coordinating all the different components of the machine to
ensure that it operates efficiently and accurately. It includes a human-machine
interface (HMI) that allows operators to monitor and control the machine
settings, as well as a programmable logic controller (PLC) that controls the
machine's automation and data collection.

 
The process involves certain steps, which will take place cyclically in auto
operation.
There is option for variation in size and quantity of the product packed. To a large
extent, the market milk is now being sold by packing in these machines
The following are the operations that go cyclically.
a) Forming of tube of packing material from film in rolled state
b) Simultaneous operation of filling and sealing
c) Movement of film to form next package
d) Simultaneous separation of filled and sealed packet while filling of next packet.
Sequence of Operation
With reference to the fig. the film roll is loaded at the backside of the filling machine
on a sliding platform. The film edge is passed over end of role contact lever, dancer
roller, UV tube and brought to the front side over to forming plates. The forming plates
rolled the flat film in to tube a certain band of overlap. Within the tube is the fluid
filling pipe enveloped. The tube then passes over to vertical seal jaws that are engaged
and disengaged with the help of an air operated piston, or in machines by mechanical
means. In between the jaws, the overlapped part of the film tube passes. The set of
jaws have one stationary and one moving jaw. The moving jaw has a nichrome rod,
supplied with variable voltage such that the heat is generated when the current passes
intermittently. During the period when the current does not pass, when the jaws are
disengaged, the cooling water being circulated in the moving jaw, cools it and prevents
continuous over heating of the sealing rod. The film is supported by Teflon cloth and
rubber cushion, as well as protected by Teflon cloth from sealing rod. This
arrangement prevents electricity passing on to the film and other parts, while allowing
only the heat to pass on to the film and partly melting and fusing the vertical joint.
Lower down the film tube, there are a pair of nip rollers giving a holding and pulling
down action, when the jaws are disengaged, making the film to move to seal the next
portion of vertical overlap.
Further lower down the film tube is engaged by horizontal jaws, at a sufficiently
below the lower edge of fluid filling pipe. This arrangement allows the formation of
lower seal of the packet, while the fluid is being filled to a known quantity. The
quantity of flow is controlled by a valve operated by a rod which is lifted by a solenoid
coil position at the top of machine, just at the feeding line from the over-head tank
carrying the fluid to be filled. While filling is taking place, a pair of flat blades
operated by spring keeps the film perfectly flat at horizontal edge so that there is no
folds and horizontal seal is perfect.
When the filling of fluid and the horizontal sealing is complete, the horizontal jaws (as
well as vertical jaws) get disengaged, and the nip rollers start rolling to bring the next
length of film tube to be filled for next packet. While the second packet is being filled,
the first packet already filled will be getting the horizontal seal of top portion of the
filled packet. When the next time the jaws open, the first packet drops down by its own
weight and weakened connection to the rest of the tube.
The above cycle of operation is repeated when the controls are in automatic operation,
while single action takes place when in manual operation during initial adjustment of
time and temperature combination for obtaining proper seal.
Controls
The Form Fill Seal Machine has various controls for the following operations.
1) Adjusting the temperature of sealing rod by controlling the electric supply, to
match to the thickness of the film to be sealed.
2) Adjusting the timing for the jaws to be engaged and simultaneously filling
operations to take place, with a known quantity of fluid.
3) Adjusting the quantity of fluid to be filled when jaws are engaged
4) Adjusting the timing for the jaws to be engaged and allow time for movement of
film to the required length of package.

 Problems faced by engineers

 The problem of TS welding is weakness in the upper or lower welding of the

tube, or the presence of cuts.
Reason: There is a problem with the heat, decrease or increase in the temperature of
the induction unit or the connected parts of the welding unit.
The treatment method is carried out in several possible ways:
a) by examining the parts of the heat induction unit and checking the heat
conduction cables and the connected busbars
b) raising or lowering the welding temperature from the machine control screen
c) examining the go gap of the faces and making sure that it is set to the
permissible limit
  Package design problem
Possible reason:
incompatibility of the cutting position of the tube coinciding with the measurement of
the cutting angle and the bar code reader lens of the tube.
Processing methods:
a) settings from the design control screen.
b) Checking the paper path and the supporting rolls, making sure there is no tension
or problem in the rolls, checking their rotation, making sure of their free
movement, checking the pulling motor, the suspension roller

 The problem of LS welding is the longitudinal welding of the tube

Possible reasons:
a) Increase or decrease in the temperature of the longitudinal welding
b) Not setting the strip path correctly
c) A problem in the longitudinal welding unit or the sensor of the unit
Processing methods:
Correctly adjust the longitudinal welding temperature. and construction on the unit

 A problem with welding the upper and lower ends (FLAP SEALING)
Reasons:
A problem with the welding heaters, the presence of dirt accumulation on the hot
air pipe unit of the heaters, or the welding temperature is not set correctly
Treatment Methods:
The heaters are checked and the hot air exit pipes of the welding heaters are
cleaned

 The Problems That We Were Faced:

1) Date Printer
3) Electricity Workshop
4) Types Of Cutters
5) Protections
6) Motor Problems
7) Types Of Relays
8) AC Driver
Electrical System
Introduction
The electrical system in a Tetra Brik filling machine. contains a great number of
electrical components and is documented in the Electrical Manual. This seclion
describes the functions of the most important and common components. and also how
the Electrical Manual is designed and how it should be used.
Components
Safety relay
The safety relay is used to supervise the emergency stop function as well as the safety
stop function on the machine. The relay can have one or two input channels. Which
must be activated in order to keep the safety output relay activated. For example.
opening a safety door Will cause the input channel to deactivate the output relay. the
safety relay Will release. and the machine Will Stop instantly.

To be able to restart the machine. the cause of the stop must be attended to and the
relay has to be reset. The relay and the alarm Will reset simultaneously. The reset
function also implies that the safety relay is functioning.
Example Of a safety relay This relay is fulfilling the highest degree of safety relay
conditions (cathegory )
The overload protection is used to protect. for example an electric motor. from
overload protection current surges and sometimes it substitutes fuses.
Example Of an overload protection, over bad protection. function diagram front
panel
I l 13 15
2 4 6
An overload protection device is equipped with two different disconnecting limitions.
one thermal and one magnetic:
• The thermal function will Irip when small overflows occur during a prolonged time
period, f.i. in case of an overload. The tripping limit for this function is adjustable.
• The magnetic function will tip when fast, high overflows occur, for example in case
of a short circuit.
A surge filter protects the electrical equipment in the machine from over-volt-Surge
tilter age peaks. such as lightning. When a very powerful peak occurs and the filler
trips, an indicator on the filler changes from green 10 The machine will set an
alarm. bul still be working. The surge filler is used. and will have to be exchanged to
protect the equipment from another overvoltage peak.
Example ot a surge tilter with indicator relay function only.
Interference filter
EMC—Electro Magnetic Compatblity
Solid state relay
LED Light Emitting Diode Interference filters are used to protect external electrical
systems from disturbances created in the filling machine (EMC-filter). In general. such
a filter consists of a combination of capacitors and coils. that Will eliminate electrical
disturbances from gelting in or out through the incoming lines.
A solid slate relay can be described as an optical electronic relay. In Other words. the
control side is electrically disconnected from the power circuit. Inside there is a LED
that gives a light pulse to transmitter (optocoupler). Solid State relays are most
commonly used When fast. livquent changes with high power, are required.
Current relay
Current 'relays are used in filling machines to supervise that certain important
components consume power and thus iilnction. For example the short stop element is
supervised on some 01 (he filling machines. This function does not need to be
temperature controlled. It is enough know that the short stop element consumes power,
in order to guarantee the function.
Current relay, Iron' panel

This card is used to amplify control signals in order to drive a DC-motor.

The driver has three internally pre-setable motor speeds chosen by two digital input
signals. One externally. analog controlled speed. is determined via three control
inputs; Ext. Speed A, B, C. Only one of them should be used.
The driver is short circuit protected on all outputs. If the motor armature output is
short-circuit. the unit Will switch off and indicate an alarm. This condition is the same
as if the current limit had been exceeded for more than 5 seconds. The red alarm
indicator will flash at current limit and show a steady light if the unit is switched off
due to overload or short circuit. The driver is reset by switching power off. or by
clearing the logical control signals. The motor field output is protected by a fuse.
The different internal speeds are selected With logical signals. These should be used to
control the motor.
Example Of a DC motor drive control, front pane
DC - Motor Drive control
selected. 
Brake card
The brake card is used to control the braking foree in a powder brake. It is used. for
example. in filling machines equipped With a PullTab unit.
 Example Ot a brake card, front panel

Stepping motor driver card

The stepping motor driver card functions as a control unit for a stepping motor.
It generates the electric pulses, which run the motor. A stepping motor has live voltage
even when it stands still, The change or angle ol' the motor, is controlled by the pulses,
generated by the card. To make the motor shaft rotate correctly, the switches on the
side panel card have to be adjusted according to the description in the MM-book.
For example, filling machines equipped with a PullTab unit. have this card.

2.1.3.1 Mechanical Training

BEARINGS

AB SKF (Swedish: Svenska Kullagerfabriken; 'Swedish Ball Bearing Factory') is

a Swedish bearing and seal manufacturing company founded in Gothenburg,
Sweden, in 1907. The company manufactures and supplies bearings, seals,
lubrication and lubrication systems, maintenance products, mechatronics
products, power transmission products, condition monitoring systems and related
services globally.[2]
SKF is the world's largest bearing manufacturer,[3] and employs 44,000 people in 108
manufacturing units. It has the largest industrial distributor network in the industry,
with 17,000 distributor locations encompassing 130 countries.[1]: 4  SKF is one of the
largest companies in Sweden and among the largest public companies in the world.[4]
A bearing is a machine element that constrains relative motion to only the desired
motion, and reduces friction between moving parts. The design of the bearing may,
for example, provide for free linear movement of the moving part or for free rotation
around a fixed axis; or, it may prevent a motion by controlling the vectors of normal
forces that bear on the moving parts. Most bearings facilitate the desired motion by
minimizing friction. Bearings are classified broadly according to the type of operation,
the motions allowed, or to the directions of the loads (forces) applied to the parts.

Motions[edit source]
Common motions permitted by bearings are:
Radial rotation e.g. shaft rotation;
linear motion e.g. drawer;
spherical rotation e.g. ball and socket joint;
hinge motion e.g. door, elbow, knee.

Friction[edit source]
Reducing friction in bearings is often important for efficiency, to reduce wear and to
facilitate extended use at high speeds and to avoid overheating and premature failure
of the bearing. Essentially, a bearing can reduce friction by virtue of its shape, by its
material, or by introducing and containing a fluid between surfaces or by separating
the surfaces with an electromagnetic field.

Stiffness[edit source]
A second source of motion is elasticity in the bearing itself.

Maintenance and lubrication[edit source]

Many bearings require periodic maintenance to prevent premature failure, but many
others require little maintenance. The latter include various kinds of polymer, fluid
and magnetic bearings, as well as rolling-element bearings that are described with
terms including sealed bearing and sealed for life. These contain seals to keep the dirt
out and the grease in. They work successfully in many applications, providing
maintenance-free operation. Some applications cannot use them effectively.

Packing[edit source]
Some bearings use a thick grease for lubrication, which is pushed into the gaps
between the bearing surfaces, also known as packing. The grease is held in place by a
plastic, leather, or rubber gasket (also called a gland) that covers the inside and
outside edges of the bearing race to keep the grease from escaping.
Bearings may also be packed with other materials. Historically, the wheels on railroad
cars used sleeve bearings packed with waste or loose scraps of cotton or wool fiber
soaked in oil, then later used solid pads of cotton.[21]
If the bearings do not function normally, they will have many symptoms, which
can be roughly divided into Six symptoms as follows:

A: High temperature.

B: Loud noise.

C: vibration;

D: The mechanical performance is unsatisfactory;

E: The bearing is loose on the shaft.

F: It is difficult to rotate the shaft

Causes Of High Temperature Endurance Problems And Solutions

1. The lubricating grease or oil is invalid or incorrect.

Solution: Select the correct grease or oil, and check the grease or oil
compatibility.

2. The oil level is too low, so the lubricant is lost from the oil seal, and the grease
in the bearing box is insufficient.

Solution: The oil level should be slightly lower than the center of the lower
rolling element, and the grease in the bearing box should fill about 1/3 to 1/2 the
space.

3. The oil level is too high or the bearing box grease is completely full, which will
cause the lubricant to stir up enough resulting in overheating or oil leakage.

Solution: add grease to the tank to 1/2; If the oil is lubricated, the oil level is
slightly below the center of the lowest rolling element.

4. Inappropriate removal of the bearing. When there is heat flow through the
shaft, the inner ring will expand excessively.

Solution: Check if the overheating bearing clearance is within the original

design range. If so, please change to a larger clearance to C3 or C4.

Causes Of Loud Noises - Endure Problems And Solutions

1. The outer ring and the bearing cover are twisted, and the shaft and the inner
ring are twisted. The reason is that the rounded corners of the box opening are
too large and the support is not enough. The shoulder fillet is too large, and as a
result, there is not enough support, and both sides are unreliable.

Solution: Adjust the trunk and shoulder opening slats.

2. Incorrect installation method, for example, directly hitting the bearing with a
hammer, as a result, there will be knocks on the bearing surface.
 Solution: Choose the correct installation method: sleeve method, heating
method, oil pressure method, etc.

3. The sealing ring of the fixed washer rubs the bearings.

Solution: tear down the lock washer or replace it with a new one.

4. The rotating parts of the machine overlap with the fixed parts.

Solution: Check carefully to avoid interference.

5. Excess clearance causes vibration.

Solution: Check the balance correction of the rotating parts of the equipment.

Causes Of Vibration Tolerance Problems And Their Solutions

1. Dirt, foreign matter, sand or other contaminants enter the box.

Solution: Clean the bearing box and replace the new oil seal.

2. Water, acid, paint or other corrosive substances enter the loading box.

Solution: Install a dust cover and improve the oil seal.

3. The inner hole of the bearing box is not round, twisted and deformed, and the
supporting surface is not flat.

Solution: Inspect the bearing box, adjust the bearing surface, and adjust the
gasket.

4. The shaft diameter is small or the transformer housing is not closed.

Solution: Check the shaft diameter, select the appropriate amount of fit, and re-
tighten the adapter cap.

5. Unbalanced load, large box hole clearance, and slipping of the outer ring into
the box hole.

Solution: Replace the bearing box with the bore diameter that meets the design
requirements.
 6. One or more bearings are coupled to produce axis linear deflection and
angular deflection.

Solution: Re-adjust the gasket so that the shaft is paired with the same straight
line.

7. Improper installation, hit the bearing directly with a hammer.

8. The bearing oil clearance is too large.

9. Equipment vibration

Reasons For Unsatisfactory Mechanical Performance

1. The bearing internal clearance is not suitable, and the tensioning force of the pre-
loading bearing is not enough, therefore, you should choose a suitable bearing.
2. Debris and dirt in the bearing box have not been cleaned, or dirt, water and acidic
contaminants have entered the box during operation.
3. The adapter housing is too tight or not too tight.
4. The bore diameter of the bearing box is not high, and the box hole is deformed and
twisted.
5. The shaft diameter is too small, and the shaft shoulder size does not match, which
interferes with the bearing.
6. The internal clearance of the bearing is too small due to excessive shaft diameter or
box hole.
7. Multiple bearing couplings, resulting in misalignment

Causes Of Bearing In Shaft Bearing Problems And Solutions

1. The diameter of the axle is small, and the inner hole of the bearing is large.
2. Insufficient interference.
3. The transformer cover is not closed enough.

Reasons For The Difficulty Of Rotating The Shaft

1. Lubrication failure, oil level, bearing clearance selection.

2. Cleanliness and debris.
3. Friction: oil seal, shaft shoulder and seal, anti-loosening plate (sun plate).
 4. The axis concentricity is incorrect, and the axial congestion is caused by the cross
positioning.
5. The bearing box has low accuracy and distortion

GEARS
A gear is a rotating circular machine part having cut
teeth or, in the case of a cogwheel or gearwheel, inserted
teeth (called cogs), which mesh with another
(compatible) toothed part to transmit
(convert) torque and speed.

Early examples of gears date from the 4th century BC in China[5] (Zhan Guo times –
Late East Zhou dynasty), which have been preserved at the Luoyang Museum of
Henan Province, China.

 725 CE: The first geared (directed) mechanical clocks were built in China.

BELTS 
A belt is a loop of flexible material used to link two or more
rotating shafts mechanically, most often parallel. Belts may
be used as a source of motion, to transmit power efficiently
or to track relative movement. Belts are looped
over pulleys and may have a twist between the pulleys, and
the shafts need not be parallel.

v-belt angle, XPZ & SPZ profile

Classic profile Width Height Remarks

Z 10mm 6mm

12.7mm = 0.5 inch width, 38° pulley angle

A 13mm 9mm
imperial belts

16.5mm = 21/32 inch width, 38° angle

B 17mm 11mm
imperial belts

22.2mm = 7/8 inch width, 38° angle

C 22mm 14mm
imperial belts

31.75mm = 1.25 inch width, 38° angle

D 32mm 19mm
imperial belts

38.1mm = 1.5 inch width, 38° angle

E 38mm 25mm
imperial belts

Narrow-profile Width Height Remarks

SPZ 10mm 8mm

SPA 13mm 10mm

SPB 17mm 12mm

SPC 22mm 18mm

High-
Performance Width Height Remarks
Narrow-profile

XPZ 10mm 8mm

XPA 13mm 10mm

XPB 17mm 13mm

 XPC 22mm 18mm-

* Common pulley design is to have a higher angle of the first part of the opening,
above the so-called "pitch line".