Design of a Saw Cutting Machine for Wood and Aluminum

Jawad Ul Haq1, Ahmed Jawad Qureshi1 and Mohamed Al-Hussein2

1
Department of Mechanical Engineering, University of Alberta, Canada
2Department of Civil and Environmental Engineering, University of Alberta, Canada

Keywords: Axiomatic Design, Table Saw, Programmable Logic Controller, Control System, Automation.

Abstract: The intensive use of wood in furniture, building, bridges, and of aluminum in transportation and construction,
underscores the economic importance of these building materials in North America. Power saws are very
useful tools for cutting and shaping such materials; however, they can cause serious hand injuries. In a table
saw operation for wood cutting, for instance, the operator’s hands are vulnerable as they are used to guide
pieces into the saw. In addition, the saw operator faces the risk of material being kicked back out of the saw
or of sustaining an eye or respiratory injury due to the presence of sawdust and other debris generating by the
operation of the saw. Meanwhile, aluminum cutting requires careful precaution and accuracy. The cutting can
be dangerous if not handled properly. The greatest challenge in this regard is securely holding the material
being cut. Furthermore, industrial requirements such as pneumatics and three-phase power supply preclude
the ready use of such machines on a domestic scale. The cutting capability of existing table saws is coupled
in such a way that it cannot cut both wood and aluminum. In this paper, a concept of a saw cutting machine
(SCM) is presented using Axiomatic Design to ensure design objectives such as safety, user comfort, usage
on a domestic scale and capability to cut both types of materials. In the presented case study, the mapping
from Customer Attributes (CAs) to Functional Requirements (FRs) and then respective Design Parameters
(DPs) resulted in an uncoupled design, in turn leading to a detailed mechanical design followed by the control
system, all based on the aforementioned design objectives.

1 INTRODUCTION machines consist of aluminum extrusions that need to

be cut in different lengths and angles. The lab has to
Forest products are a major contributor to the outsource the cutting to third-party companies,
Canadian economy. (Canada, 2013) In 2013, resulting in increased costs and delays of the machine
production in the forestry sector contributed $19.8 development program.
billion to the economy. In a global context, Canada In order to overcome the aforementioned
has the world’s largest forest product trade balance. challenges, the research team began investigating
The aluminum industry is another important sector of SCM solutions with the design objectives of (1) the
Canada’s economy, with aluminum products export ability to cut both wood and aluminum, (2) versatility
valued at $10.8 billion in 2016, an increase of $211 to be deployed in a lab or domestic scale without
over 2015; (Canada ranks third in aluminum three-phase industrial power supply or complex
production in the world after China, and Russia). pneumatics, (3) safety mechanisms to enable safe use,
The motivation for the development of the saw
cutting machine (SCM) described in this paper arose
out of a broader research initiative at the University
of Alberta (Canada) to develop a semi-automated
wood framing machine
Figure 1 and a semi-automated light-gauge steel
framing machine Figure 2. The primary objective of
both machine development projects is to support the
growth of panelized construction in North America’s
building construction sector. The structures of both Figure 1: Wood framing machine.

456
Haq, J., Qureshi, A. and Al-Hussein, M.
Design of a Saw Cutting Machine for Wood and Aluminum.
DOI: 10.5220/0006909704560464
In Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics (ICINCO 2018) - Volume 2, pages 456-464
ISBN: 978-989-758-321-6
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
 Design of a Saw Cutting Machine for Wood and Aluminum

specialty blades; and brakes can only be used when

cutting nonconductive materials. (Graham and
Chang, 2015) provide a quantitative estimate of the
economic benefits of automatic protection systems
that could be deployed in new table saw products. The
general consensus among researchers is that the
benefits of automatic protection are likely to
outweigh the incremental costs of implementation
significantly. (Schwaneberg et al., 2012) discuss the
Figure 2: Steel framing machine. use of a LED-based sensor system to distinguish
human skin from work pieces. In this context, it is
and (4) capable of angled cutting started and resulted thus of interest to investigate new technology to
in a design discussed in the following sections. automate the process by designing a machine using a
In order to overcome the aforementioned systematic method of design. (Farid and Suh, 2016)
challenges, the research team began investigating Axiomatic design is a design method introduced by
SCM solutions with the design objectives of (1) the Nam P. Suh. It consists of four domains: consumer,
ability to cut both wood and aluminum, (2) versatility functional, physical, and process. These domains are
to be deployed in a lab or domestic scale without interlinked in such a way that customer needs—
three-phase industrial power supply or complex referred to as customer attributes (CAs)—in the
pneumatics, (3) safety mechanisms to enable safe use, customer domain are transformed into functional
and (4) capable of angled cutting started and resulted requirements (FRs) in the functional domain. FRs, in
in a design discussed in the following sections. turn, are satisfied by design parameters in the physical
The paper is divided into eight sections. Section 2 domain. Product variables (PVs) are determined from
reviews the relevant literature with a focus on DPs in the same manner. Axiomatic design as
potential safety hazards, Section 3 elaborates on the described above has been used in many fields, such
design objectives and describes the research as software design (Suh and Do, 2000) and control
methodology, Section 4 explains the implementation system design (Lee, Suh and Oh, 2001). (Negahban
of Axiomatic Design to form an uncoupled design, and Smith, 2014) provide a comprehensive review of
Section 5 presents the mechanical design, and Section discrete-event simulation in which the discrete-event
6 the implementation of the control system to meet model of a system can be implemented using a
the design objectives mentioned in Section 3. Section computer. This simulation-based approach can aid in
7 describes the discrete-event simulation model of the understanding the system under study in terms of
SCM, followed by Section 8, which summarizes the cycle time, utilization of different resources,
research achievements. improvements in design, and production levels.

2 LITERATURE REVIEW 3 METHODOLOGY

Table saws are associated with more injuries than any The design objectives for the machine are as follows:
other type of woodworking tool.(Shields, Wilkins and
Smith, 2011) estimate that 565,670 table-saw related • Capable of cutting both wood and aluminum
injuries were treated in the United States during the • Can be used in a lab or domestic scale
period 1990–2007. Injuries to fingers/thumbs were • Ensures safety and operator comfort
the most common overall (86%—486,181 of • Can accommodate angled cutting
565,670). (Chung and Shauver, 2013) discuss
SawStop, a technology designed to stop the saw blade In general, the design of machines consists of
when contact is made with skin, resulting in a small conceptual and detailed design processes. Overall the
cut rather than a serious laceration or amputation. A factors which affect the most characteristics and the
few disadvantages associated with SawStop, though, cost are determined in the conceptual stage.
are that the force required to quickly stop the saw Axiomatic design is a design methodology to
blade damages the blade and brake beyond repair systematically transform the CAs into FRs and then
such that they must be replaced each time the brake is respective DPs, and PVs. In this paper; Axiomatic
triggered; furthermore, the brake cartridges are blade- design is utilized in the conceptual design process that
specific; there are no brakes available for some further lead to detailed design. The FRs for the SCM

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ICINCO 2018 - 15th International Conference on Informatics in Control, Automation and Robotics

are defined on the basis of CAs, and corresponding After the top level design, FRs and DPs are
DPs are selected. The detailed design is carried out on decomposed and Table 1 illustrates the second level
the basis of decisions made in the conceptual stage. FRs and DPs.
Computer Aided Design (CAD) model of the SCM is
developed in SOLIDWORKS. Control system of the FR3= Facilitate operator
SCM is realized on Programmable Logic Controller FR4= Industry power & pneumatics alternative
(PLC) using Sequential Function Chart (SFC) which FR5= Angle cut
is one of the IEC 61131-3 languages. In order to FR6= Safety
estimate the performance of the machine, discrete-
event modelling technique is used. Arena input DP3= Automation using stepper motors & Human
analyzer by Rockwell automation is used to select the Machine Interface (HMI)
distribution of each task in the simulation model. DP4= Single phase power supply & force controlled
actuators
DP5=Rotary table
4 AXIOMATIC DESIGN DP6= Sensors based mechanical assembly

Design process in Axiomatic design is top-down, in The low level FRs and DPs decomposition is as
follows:
which the initial concept is decomposed to design
details by zigzagging. The relationship between FRs
and DPs is given as FR3.1= Use automation
FR3.2= Facilitate interaction with machine
FR4.1= Use domestic power
{FRs} = [A] {DPs} (1)
FR4.2= Use pneumatics alternative
FR6.1= Incorporate safety measures against airborne
FRs are a minimum set of independent requirements
debris
that completely characterize the functional needs of
FR6.2= Make sure user is at a safe distance
the product in the functional domain. Each FR is
independent of every other FR at the time the FRs are
DP3.1= Motors
created. [A] is defined as the design matrix. When [A]
DP3.2= Human Machine Interface
is the diagonal matrix, the design is called uncoupled
DP4.1= Single phase power supply
design which is ideal. When [A] is lower triangular
DP4.2= Forced controlled actuators
matrix, the design is called decoupled and preferred
DP6.1= Safety enclosure
in absence of uncoupled, while all the other designs
DP6.2= Ultrasonic sensors
are called coupled. DPs are the physical variables in
the physical domain that characterize the design that Table 1: Initial design matrix.
satisfies the specified FRs. When DPs do not take
their detailed physical form, the corresponding FRs
1.1 Cutting RPM

need further division. Based on DP3, FR3 of the SCM

2 Cut aluminum

is decomposed into two sections as FR3.1 and FR3.2.

1 Cut wood

The FR5 needs no further decomposition as DP5 has

1.2 Cutting
feed speed

FRs/DPs
taken its detailed physical form.
The axiomatic design of SCM has three parts:
CAs, FRs, and DPs. At the beginning of the design
process, the needs of the customers (i.e., CAs) are
1 Need to cut x
taken into account in order to generate the FRs and
wood
then the DPs. The top-level design is given as 1.1 Use x x
follows: cutting RPM
CA: Wood and aluminum cutting capability, safety, 1.2 Use feed x x
user comfort, usage on a domestic scale, and angled speed
cutting capability. 2 Need to cut x
aluminum
FR0: Carry saw, motors, sensors (electrical 2.1 Use x x
components) inside a safe cabinet (mechanical) cutting RPM
DP0: Programmable logic controller (PLC)- 2.2 Use feed x x
controlled saw cutting machine speed

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 Design of a Saw Cutting Machine for Wood and Aluminum

Table 2: Low level design matrix.

6.2 Ultrasonic sensors

aluminum feed speed

3.2 Human Machine

6.1 Safety enclosure

4.2 Force controlled
3.1 Stepper motors
1.1 Apply cutting

1.2 Apply cutting

2.1 Apply cutting

2.2 Apply cutting

wood feed speed

4.1 Single phase

aluminum RPM

power supply
FRs/DPs

wood RPM

actuators
Interface
1.1 Use cutting RPM x

1.2 Use feed speed x

2.1 Use cutting RPM x

2.2 Use feed speed x

3.1 Use automation x

3.2 Ease interaction with machine x

4.1 Use domestic power x

4.2 Use pneumatic alternative x

6.1 Incorporate safety measures
x
against airborne debris
6.2 Make sure user is at a safe
x
distance

The one obvious coupling which is not discussed for make the design matrix square. The final uncoupled
this case study is the type of saw. A universal saw is design matrix is shown in Table 2.
proposed to uncouple the design; although this will
compromise the quality of the cut in the case of
aluminum, it satisfies the design objectives and the 5 MECHANICAL DESIGN
purpose for which the machine is being designed.
The CAD model of the SCM as shown in Figure 3 and
× ×
Feed speed = (2) Figure 4 is developed in SOLIDWORKS, a solid
modelling computer-aided design tool that runs on a
computer. The machine design is flexible, it should
Feed speed: inches per minute
be noted, with regard to the length of material to be
RPM: revolutions per minute
cut. Depending on the length of the profile the table
Chip load: inches
can be attached along with a motor-controlled length
measurement unit, or the profile can be put directly
The initial design matrix results in a coupled design
on the main cutting station. The force-controlled
due to the fact that feed speed and RPM are related
actuators are used to clamp the piece firmly. A safety
(2). Feed speed and RPM have to be adjusted
enclosure protects against any debris or particle
according to the material being cut. The second
hitting the operator while working, and the rotary
concern is that the number of FRs is greater than the
table is used to achieve the cut angle.
number of DPs. The first step towards uncoupling the
initial design is a permutation that results in a better 1. Table
design but still a coupled one. To solve the issue of 2. Cutting length measurement unit
feed speed and RPM coupling, a software solution is 3. Main cutting station
used which is implemented on PLC that sets the 4. Force-controlled actuators
desired feed speed and RPM to cut the given material. 5. Safety enclosure
The second design issue of inequality in numbers of 6. Rotary table
FRs and DPs is addressed by adding more DPs to

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6 CONTROL SYSTEM operator’s safety; and (5) engagement of saw motor

and feed motor to cut material.
Machine control system is a collection of hardware Loading is the manual operation in which the
and software, designed to coordinate the output of operator picks a profile and places it in the designated
each individual component to achieve the desired area of the machine. Once the loading is done, the
machine functionality. next step is to input material and cut specifications.
The HMI facilitates the interaction between the
operator and the machine. The information is inputted
to the machine by either of two methods. In the first
method, a computer numerical control (CNC) file
containing the complete information about the profile
is uploaded, and the machine reads the file in a
sequential manner to perform the operation. The CNC
file contains information such as the material,
coordinates, and angle to cut. In the second method,
the operator loads the profile and inputs the
information manually. Once the operator has inputted
the information, the machine executes safety
measures before carrying out the cutting operation. It
looks for a valid CNC file or coordinates to cut,
Figure 3: SCM CAD model. ensures by means of ultrasonic sensors that the
operator is at a safe distance, clamps the profile, and
engages the safety enclosure. If all the conditions are
met, then the PLC sends a command to the saw motor
to engage and perform the cut. Apart from these
safety checks, there are also emergency shutdown
(ESD) push-buttons which can be used to halt the

Figure 4: SCM main cutting station.

6.1 Process Flow

The process as shown in Figure 5 starts with the
manual loading of the wood/aluminum profile. A
human–machine interface (HMI) is used to obtain the
desired length and angle to be cut, followed by
clamping in which load sensors are used to apply the
required force to clamp the wood or aluminum being
cut. The saw motor waits for the safety enclosure to
come down and for the operator to move a safe
distance away.

6.2 Sequence of Operation

The sequence of operations consists of (1) loading;
(2) length and angle input; (3) clamping; (4)
engagement of safety enclosure and sensors for Figure 5: Process flow chart.

460
 Design of a Saw Cutting Machine for Wood and Aluminum

machine in case of any abnormal scenario. To clamp and 6.3.2 Implementation of HMI
to replace the pneumatic system, feedback force-
controlled actuators are used. Based on the material Vijeo Designer provides great flexibility in designing
selected, the actuators apply the right amount of force graphical user interfaces (GUIs), where the nature of
and the feed motor selects the desired feed speed to the operator’s interaction with the machine dictates
cut the material. Once the material is cut, it is the design of the HMI. A well designed HMI aids the
unclamped in order for the operator to collect it. operator in understanding the previous, ongoing, and
future tasks. It provides great advantages in terms of
6.3 Implementation of Control System providing a user-friendly interface even for users
without a relevant technical background, in which
Automation of the sequence of operation is realized warnings and emergency situations can be communi-
by means of PLC as follows: cated more efficiently by using bright colors to attract
• Discrete inputs from proximity sensors for the operator’s attention, and a single button can be
wood/aluminum detection. assigned multiple tasks providing more flexibility in
• Discrete inputs from limit switches for safety
and initial calibration.
• Analog inputs from load sensors to clamp
wood/aluminum.
• Analog inputs from ultrasonic sensors for
operator safety.
• Motor drive outputs to linear actuators for
clamping.
• Motor drive outputs to cut wood/aluminum at
desired angle and length.
• HMI to facilitate the automation process.
Once the hardware is known, next step is to select the
software to make harware operational. The PLC code
is developed in SoMachine, while the HMI code is
developed in Schneider Electric’s Vijeo Designer.
(Electric, 2018b) SoMachine is a software tool for
developing, configuring, and commissioning the
entire machine in a single software environment,
including logic, motion control, and related network
automation functions while Vijeo Designer is an HMI
configuration software. (Plaza, Medrano and Blesa,
2006) IEC 6113-3 standard is a global standard for
control programming that helps to improve software
quality. Ladder programming has several drawbacks, Figure 6: SCM code in SoMachine.
including weak software structure and limited capacity
to handle complex data structures. (Jetley et al., 2013)
discuss the comparison of graphical IEC 61131-3
programs, asserting that it is easier to trace the error
with graphical languages as compared to textual.

6.3.1 Implementation of Code

The code for SCM is written in Sequential Function
Chart (SFC), which is one of the IEC 61131-3 langua-
ges. Each block in SFC has three portions: entry, main
body, and exit conditions. The program flows through
these portions in a sequential manner. The flow
between blocks is governed by transitions, which are
Figure 7: Material selection in Vijeo Designer.
conditions the satisfaction of which drives the flow of
the program on to the next block as shown in Figure 6.

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7 DISCRETE EVENT
SIMULATION
Discrete-event simulation describes a process with a
set of unique, specific events in time. Arena by
Rockwell automation is used in the present research
to build the SCM model with its key performance
parameters such as cycle time and operator
utilization. The model as shown in Figure 10 reads a
CNC file that contains information about a profile,
such as material, cut coordinates, and cut angle, in a
sequential manner. The task times and triggers are
Figure 8: Operator input in Vijeo Designer. assumed to provide the basis for statistical analysis
and hypothesizing distribution.
terms of coding. The GUI implementation in Vijeo
Designer is shown in Figure 7 and Figure 8.

6.4 Ethernet/Ip Architecture

One of the complex tasks in the development of PLC-
based control systems is wiring. Having a relatively
small numbers of devices in a control system can
result in a complex wiring system which occupies
more space and is difficult to troubleshoot. (Electric,
2018a) Ethernet/IP uses two protocols for the
transport layer: Transmission Control Protocol (TCP)
and User Data Datagram Protocol (UDP). TCP is
acknowledged while UDP is unacknowledged
protocol. TCP is used for non-control messages while
UDP is used for Input/output (I/O) messages. Tested
validated document and architecture (TVDA)-based Figure 9: SCM Ethernet/IP architecture.
Ethernet/IP improves efficiency in the design and
planning phase. Based on inputs/outputs described in 7.1 Model Discussion
Section 6.3 Ethernet/IP architecture is used for the
machine described in this paper due to the following A discussion of the simulation model is given in this
advantages: section. In Arena, a model is built using a “process”
module that holds the “entities” for a specific period
• Ability to access the machine from anywhere,
of time. The entities flow through different process
anytime via Ethernet for remote monitoring.
modules to provide a valuable insight into machine’s
• Flexible in terms of adding an Ethernet/IP
key performance indicators at the end of the
adaptor at any time.
simulation. The model for the SCM reads a
• Efficient in terms of device integration and
spreadsheet extracted from a CNC file and scans the
configuration, and the architecture can easily
total number of cutting operations in the file prior to
be modified.
processing. It then generates entities equal to the
With embedded Ethernet/IP communication, a number of cutting operations. The “Hold Entity”
PLC can communicate with 16 slaves in 10 ms. The module holds the next entity, which is the next cutting
Ethernet/IP architecture for the SCM is given in operation, until the previous entity, which is the
Figure 9. previous cutting operation being processed by the
model, finishes. The “Decide Operation” module
decides the material on the basis of a string variable
that looks for either “WD” for wood or “AL” for
aluminum in the file and then guides the respective
entity to pass through the modules designated for the
respective material. The “Load Profile” and “Collect

462
 Design of a Saw Cutting Machine for Wood and Aluminum

Piece” modules share a common resource, which is 7.1.1 Case Study

the operator. The “Length” and “Angle” module task
times, it should be noted, are dependent on the To illustrate the effect of different profiles with
coordinates and proportional to the cut length and different cut and angle coordinates on the key
angle in the CNC file. The model consists of performance indicators, for instance, cycle time and
following main modules sections (1) initial utilization of the operator, Table 3 shows the
calibration; (2) CNC file reading; (3) aluminum summary of results obtained from the model. For the
cutting; (4) wood cutting; and (5) ending. (1) accounts profile case studies as illustrated in Table 3, the
for the time taken in homing the motors and initial simulation model generates a total of five entities, as
system delays when the machine is powered on, (2) there are five cutting operations at time zero. The
deals with reading of the CNC file and deciding the “Hold Entity” module holds the next cutting
operations accordingly, (3) accounts for the time operation until the previous entity or cutting operation
taken in cutting the aluminum, (4) accounts for the exits the model, and sends a trigger to the hold
time taken in cutting wood, and (5) indicates when all module through the signal module. The simulation
the operations on the profile are done. keeps running until all the entities generated have
exited the model.

Figure 10: SCM simulation model.

Table 3: Simulation results summary.

Profile Dimensions Material Cut Lengths Cut Angle Average Average
WxHxL (inch) (θ) Cycle Time Operator’s
(inch) (minute) Utilization
(%)
Profile 1 1.57x1.57x78.74 Aluminum 12,24,48 45,60,0 3.3 81

Profile 2 1.5x3.5x78.74 Wood 12,36 0,0 2.1 70

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8 CONCLUSION and Factory Automation, ETFA. doi: 10.1109/

ETFA.2013.6647938.
Lee, K. D., Suh, N. P. and Oh, J. H. (2001) ‘Axiomatic
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saw involves a stationary saw motor in which the Manufacturing Technology, 50(1), pp. 109–114. doi:
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aluminum cutting requires extra precaution and manufacturing system design and operation: Literature
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