ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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Mini Project: Auto Components Ltd. Case Study
1. Introduction
Auto Components Ltd. is a medium sized company with five production facilities
throughout the U.K. Each plant produces a variety of components for various truck and
car manufacturers. Each plant has a certain amount of autonomy and has grown to
supply the needs of manufacturers in its vicinity.

A facility located in north Devon has traditionally concentrated on producing small,
relatively simple components. Over recent years, much of this work has been put up for
competition with Auto Components Ltd. frequently losing business to specialized, more
modern suppliers.

One of the few areas where the north Devon facility is still competitive is the production
of valves. A variety of such devices are built for a range of applications.

The ZA valve lines produce valves coated with titanium nitride. The coating makes the
valves resistant to damage by water, grit or mud. It is also makes the valves expensive.
They are therefore only used on luxury sport utility vehicles.

The ZA810 line produces valves of both 20 and 25 cm. Other than the length, these
valves are identical in every respect.

2. The Project
You have been employed by the management of the north Devon facility to produce a
comprehensive simulation study of the ZA810 production line.

You are required to produce a professional report for the company detailing the results
of your study and the improvement recommendation(s) that you would make to the
system. Include any statistical analysis that you perform to support your
recommendations. You should make at least one improvement suggestion, supported
by arguments and data.

The simulation model will be created in the software package Witness. The model must
be graphically well presented. Any data that you think will aid in the understanding and
verification of the model should be shown dynamically as part of the model display.
There are 3 initial models available for use on the ECMM172 ELE page. These models
are not perfect, but are approximating the reality in an acceptable manner. You may
create your initial model, or you can use any of the initial models provided.

It is envisaged that the management will continue to utilise the model after the end of
the simulation study, so it is necessary for you to provide documentation explaining the
layout and logic of the model.

ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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3. Submission
Both the report and simulation model (two different files) should be submitted by 27
March 2020 at 5PM. If you submit later than 5PM, your mark will be capped at pass
(50) according to the university’s regulations.
4. Assessment
You will be required to submit individually 2 files on the ECMM172 ELE page:
- The simulation model. The simulation file’s name must include your name (e.g.
john_smith.mod).

- The Project Report. Your report should have a maximum of 1200 words. Tables
and graphs are not included in the word count. Your report must include a short
executive summary giving a brief description of what was carried out and your
findings. The executive summary1 should be no more than 150 words.

The simulation file will be used to check the consistency between your report and the
simulation.
The Project Report will be checked against plagiarism.

Assessment of the project is based upon the Project Report using the following
criteria:
a. Executive summary 10%
b. Explanation of the improvement(s) logic 30%
c. Analysis of the improvement results 40%
d. Report presentation 20%


Please note that the majority of the marks are NOT given for the simulation itself,
but for the quality of your explanation, analysis and improvement suggestion(s).
In the past some students have submitted a near perfect model and a terrible
report. Taking this approach will not get you the best mark.
Please also note that there is no ‘perfect simulation’ of a real system. In order to
get as close as possible to the details of this manufacturing systems, you will have
to make some assumptions. Please state clearly these assumptions!

1 An executive summary, or management summary, is a short document or section of a document,
produced for business purposes, that summarizes a longer report or proposal or a group of related reports
in such a way that readers can rapidly become acquainted with a large body of material without having
to read it all. It usually contains a brief statement of the problem or proposal covered in the major
document(s), background information, concise analysis and main conclusions. It is intended as an aid to
decision-making by managers and is the most important part of a business plan
ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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Description of the ZA810 Valve Production Line
(Refer to attached Data Sheet and Process Diagram)

Raw material (bar stock) for both valve types is delivered to buffer STORE1. They are
delivered via a forklift from the parts crib with a particular delivery schedule. Auto
Components Ltd. have a contractual agreement with the supplier of bar stock that
guarantees the part crib will never run empty.

SAW takes a single bar from STORE1, processes it, and places it in STORE2. DRILL
takes a single bar out of STORE2, processes it, and places it in STORE3. Finally
COATER takes a single bar from STORE3, processes it and dispatches it to the
ROLLER conveyor.
Both DRILL and SAW each have 2 separate tools that are used for each operation. Data
has been provided on the replacement frequency of these tools. In addition the
breakdown profiles of SAW, DRILL and COATER have been collected.
The production line employs three machinists, LAB1, LAB2 and LAB3. LAB1 and
Lab2 are responsible for SAW, DRILL and INSPECT. LAB3 is responsible for
COATER.

A series of ten manual workstations, five of them produce 20 cm valves and the other
produce 25 cm valves, are simulated as two fixed conveyors, STAT_20 and STAT_25
respectively. Both conveyors need to have a carrier or pallet to position the bars as they
move from station to station. To accomplish this, the LOAD operation takes a pallet
from PALLET STORE and places a bar from ROLLER in it. Fifty percent of the pallets
go to STAT_20 and the other fifty percent go to STAT_25.

The UNLOADING operation disassembles the pallets from STAT_20 and STAT_25.
It sends pallets down the RETRIEVAL CONVEYOR, which deposits the pallets back
into PALLET STORE.

The valves are then placed in to the INSPECT operation. The INSPECT process
consists of four distinct cycles.

Quality has been a big issue in the past with only 85% of the valves passing inspection.
Those that do pass are shipped. Rejected valves are placed into the REWORK buffer
for repairs. The repair time, which depends on what valve needs to be repaired, is
simulated as a minimum delay within the buffer. Any repaired valves will be inspected
again to ensure their quality.

The management require displaying separately the total numbers of 20 cm and 25 cm
valves that have been reworked. In addition, calculation and display of the average
downtime of the COATER, DRILL and SAW machines is also required.

The facility works three shifts a day, 7 days per week. The shift applies to part arrivals
and labour.

The management have completed a primary study of the system and have suggested a
warm-up time of 600 minutes; this may be checked for accuracy. They are interested in
a production time of at least 1 week in addition to the warm-up period.
ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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A1. Data Sheet

Bar Stock delivery schedule: 50 bars every 240 minutes

Buffer capacities:
STORE1: 1000 parts
STORE2, STORE3: 10 parts

Table A1-1. Machine Cycles
Machine Cycle Time [min] Operation Labour
SAW Mode = 3.7, Min = 2.9, Max = 4.3 LAB1 or LAB2
DRILL 5.2 LAB2 or LAB1
COATER 2 LAB3
LOAD 4 -
UNLOADING 4 -


Table A1-2. INSPECTION Cycles
Description Cycle Time [min] Labour Requirement
Position Valve 1 LAB1 or LAB2
1st Automatic Test 3 -
Calibrate 1 LAB2 or LAB1
2nd Automatic Test 2 -


Table A1-3. Tool Replacement Data
Machine Tool Ops. Between
Tool Changes
Change Times [min] Labour Requirement
SAW 1 50 1.5
LAB1
SAW 2 75 2.1
DRILL 1 45 1.2
LAB2
DRILL 2 35 2.8


Table A1-4. Machine Breakdown Information
Machine Breakdown
Frequency
Repair Duration Labour Requirement
SAW Mean = 60 min
Busy
(Neg. Exp.)
Mean = 20 min
K = 3
(Erlang)
LAB1 and LAB2
(Two labours are
required)
DRILL Every 100
Operations
See Table A1-5 LAB1 and LAB2
(Two labours are
required)
COATER Mean = 120 min
Busy
(Neg. Exp.)
Mean = 20 min
K = 3
(Erlang)
LAB3


ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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Table A1-5. DRILL Repair Times
Range [min] Frequency
0 – 10 12
10 – 20 8
20 – 30 18
30 – 40 4
40 – 50 10
50 – 60 16


Table A-6. Conveyor Information
ROLLER Data
Bar Length 30 cm
Length of ROLLER 2.4 m
Speed of ROLLER 3 m/min
STAT
Pallet Length 60 cm
Length of STAT_20 3 m
Length of STAT_25 3 m
Speed of STAT_20 and STAT_25 3 m/min
RETRIEVAL CONVEYOR
Length of RETRIEVAL CONVEYOR 6 m
Speed of RETRIEVAL CONVEYOR 3 m/min
Number of Pallets 10
Capacity of PALLET STORE 10


Table A-7. Valve REWORK Information
Item Data
20 cm Valve REWORK Time 16
25 cm Valve REWORK Time 20
REWORK Capacity 10 Valves


Table A-8. Shift Patterns
Shift Period Shift 1 Shift 2 Shift 3
Start 12:00 AM 8:00 AM 4:00 PM
Lunch (1 hour) 4:00 AM 11:00 AM 8:30 PM
Finish 8:00 AM 4:00 PM 12:00 AM

ECMM172 MANAGEMENT SCIENCE
SIMULATION MINI PROJECT

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SECTION: ZA810 VALVE PRODUCTION AUTO COMPONENTS LTD.
BIDEFORD, NORTH DEVON FLOORPLAN

DRAWN BY: DATE: 15/01/19 SCHEMATIC

STORE1 SAW
STORE2 STORE3
DRILL COATER ROLLER
LOAD
PALLET
STORE
STAT_20
STAT_25
RETREIVAL
CONVEYOR
UNLOADING INSPECT
INSPECT
REWORK