IE 202 WORK STUDY & ERGONOMICS
SPRING 2012
WORK STUDY PROJECT
DESIGN OF A FIRE RESCUE TRUCK ASSEMBLY LINE
1. Introduction
This project aims at enabling you to practice your skills in Work Study. In the project each
group consisting of six students is supposed to design an assembly line to assemble the Lego
fire rescue truck1 shown in Figure 1, in which the group members will be not only the
designers but also the operators/stations of the assembly line. The objective is to design an
assembly line with the maximum possible throughput (i.e., number of trucks produced per
unit time), while at the same time keeping the work-in-process (WIP) inventory at the
minimum possible level.
Figure 1. Lego fire rescue truck that is used in the project
2. Guidelines for the project
In order to guide your project study, a guideline consisting of four steps is provided for you.
Note that these four steps are similar to the steps of systematic approach in methods
engineering (refer to Chapter 8 in the lecture notes). Only forgotten step is the problem
definition step. Since the problem is clearly defined by this project manual, which is the last
sentence of the introduction section, you may skip the problem definition step. What you are
supposed to do is to follow the four-step method given below to complete your project. The
project involves the following steps:
1
The kit for fire rescue truck, whose product code is L6911.
1
Step 1: Analysis of the process
In this part you should break the whole assembly process into work elements. In order to
identify the work elements, you may refer to the instructions given with the toy kit. After
identifying the work elements you should develop a precedence diagram for the assembly
process. Notice that you are free to change the sequence of the tasks given in the instructions
given with the toy kit. Therefore, please be careful about imposing precedence relationship
between the tasks. Otherwise you may suffer from unnecessary precedence relationships.
After developing the precedence diagram, you should measure the time required to perform
each work element using stopwatches. Later on, the precedence diagram and the work
element times are used in step 2 for the assembly line balancing.
Step 2: Evaluation of the alternative models and selection of the best one
In this step, you should first decide on the number of work stations (or operators) in the line.
Note that although this seems to be a simple task, it may be one of the most critical decisions
in your project (you will see the reason behind that in step 3). After deciding on the number of
work stations in the line, you should come up with alternative assembly line models using the
assembly line balancing heuristics discussed in the class, based on the precedence diagram
and the time measures that you obtain in step 1. At this step, you will identify the best
solution based on the throughput levels, which is the reciprocal of the cycle time, and the line
balance efficiencies. However, as you will see in step 3, in the implementation phase, you
should also take into account the WIP in addition to throughput and line balance efficiency. In
this sense these three performance measures can be seen as the critical success factors of the
project. Note that at this level, the assembly line model that you have proposed is only an
abstract view of your real design, which you have not observed yet. Only after the
implementation step, which will be discussed next, your model will become a real assembly
line.
Step 3: Implementation of the best method and the demonstration
After deciding on the best assembly line model, groups will implement/test their line models.
In this manner, groups can recognize the shortcomings of their design, and then have the
opportunity to improve the process. During the implementation, if you observe a mismatch
between your assembly line design that you obtain and its implementation, you may need to
go over steps 1 and 2 once more to check whether you have made a mistake in these steps and
update your assembly line accordingly if needed. Note that the assembly line model(s) that
you have built in step 1 and 2 are deterministic. Therefore, WIP, which is due to stochastic
nature of the problem, can only be observed at this phase, while you are implementing your
model. In this step, you should also focus on WIP.
After you have built your assembly line, you can improve your assembly process further by
using work and motion study principles that you have learnt in the class. For this purpose it is
highly recommend for you to revisit Chapters 8, 9, 10 in the lecture notes. Therefore,
although in this project you are dealing with a line balancing problem, any kind of a method
improvement will be appreciated.
In order to make implementation practices you will have practice hours. During these practice
hours, you may use the trucks that are provided by the instructor/teaching assistant. Practice
hours will be held in Lab HA-340. You need to make appointments to use the room. To make
appointments you may contact the teaching assistant. Note that you will obtain work element
2
times, which are required in the first two steps, again during these the practice hours using the
kits and the stopwatch times provided by the course staff.
Finally, groups will be asked to demonstrate the performances of their assembly lines. To this
purpose 8 minutes will be given for each group. The evaluation of the demonstrations will be
based on the throughput of each line and the WIP required to provide that throughput. Date
for the demonstrations and its schedule will be announced later. All group demos will be
recorded by a camera.
In the demonstrations, stop watch time recording, disassembly tasks will be provided by the
instructor and teaching assistant. Thus, different from Lab 1, you don’t need to allocate any of
your group members as dissassembler or time recorder. Therefore you may dedicate all your
group members to the production/assembly process. Each student working as a single station
in the production line, number of stations in your assembly line is limited by the number of
students in your group. Of course, you may consider using utility workers especially to supply
parts to stations or to help workers who fall behind, of course at a cost of one assembly
operator. Note that although you have decided on the number of stations in step 2, you may
need to try with alternative scenarios with different number of stations (operators). In this
case, you may need to go over steps 2 and 3 once more.
For the practice hours, each group is given a few kits of fire rescue truck; while in the
demonstration, you are given ten kits of trucks parts. Therefore, you have to guess your
demonstration performance (the one with ten kits) based on your performances in the practice
hours (the one with the five kits). Note that it is the group’s responsibility to ensure that there
will be no missing parts/kits/tools or any damages to the parts/kits/tools that the course staff
has provided. In such a case the group who is responsible for the case should obtain the
corresponding part/kit/tool.
Step 4: Reporting the project.
You are also supposed to write a project report. This report should cover all the steps that are
described above. Based on the demonstration performance, you should also discuss on the
differences between the theoretical results and practical performances. If you think that there
is mismatch between these two performances, you should try to explain it. If not, give reasons
how you achieve this result. After all, in terms of the critical success factors you should
evaluate your line performance. Such an evaluation is meaningful only after the
demonstration, when you have seen other assembly line designs. To sum up, your project
report should also involve a discussion on the evaluation of your performance in the
demonstration. Note that although writing the project report seems to be the final step of your
project, you should start writing the report whenever you progress in the project. Therefore,
while you are proceeding with the project, at the same time you should continue with the
report.
There is no page limitation in the report. While writing your report you should follow the
summer training report format. Therefore, please read the instructions for the summer training
report carefully. While reporting your project, you may follow the steps that you have
followed in the project. The reports should binded by a spiral spine with transparent front
cover page. While submitting your report, you should also present a CD that includes
 a video of your demo
 soft copy of your report
 any spreadsheet file that you have used.
3
The CD should be attached at the back cover page of the report.
Due date for submitting the report will be announced later. You may submit your report to the
instructor or the teaching assistant and don’t forget that late deliveries will be penalized.
3. Academic Integrity, Peer Evaluation, Honor Code
The students, who are expected to be a graduate of Çankaya University Department of
Industrial Engineering, are expected to act honestly and ethically. Therefore, any form of
dishonesty will not be tolerated. Also, don’t forget that you only get credit for group’s
individual work. For this purpose each student will evaluate the performance of his/her group
members to grade the individual performances.
After completing your project report, being an Industrial Engineering Department student,
you should declare your understanding and belief in the Honor Code stated by the department
for the examinations and assignments by writing the following statement on the cover page of
the project report:
We hereby declare that, except where we have indicated, the work we are submitting in this
project report is our own work.
[Sunmakta olduğumuz bu proje raporunun, belirttiğimiz kısımların haricinde, tamamen kendi
eserimiz olduğunu beyan ederiz.]
4. Grading
The project will be graded based on the written reports and the demo performance. Members
of a group may receive different marks from the project, depending on the individual
performances. Finally, the project will be evaluated based on the demonstration performance
(60%) and the written report (40%).
References
AMMAR, S. and WRIGHT, R. (1999) Experiential learning activities in Operations
Management, Intl. Trans. in Op. Res., 183-197. Vol. 6.
IRAVANI, S. M. R (2009). Design of a Push Production (Assembly) Line. Retrieved
November 13, 2000, from Northwestern University, Department of Industrial Engineering
and Management Sciences Web site:
http://users.iems.northwestern.edu/~iravani//prolab/assembly_push.html
4