1. Report on what I did during the week.
01/03/09 – 06/03/09
Compiled by: Tshepo Makgakge
Position: Industrial Engineering Trainee
Submission Date: 09 March 2009

2. 1. Terms of reference
On the 24th
November 2008, Ms Charity Van Wyk the process engineer of Plastop
requested a report on what I (Tshepo Makgakge) did during the week and what I saw.
The report with recommendations is due on the 09 March 2009.
2. Procedure
Define- The activity under investigation was colour changing, apparently the colour
changes take too long and which cause machine down time.
Measure-The time it takes to change colours was measured and then recorded.
Analyze-The times recorded to information that can be used in coming up with an
improved method.
Interpret-the information in terms of drafting graphs.
3. Findings
Colour Change Durations
Machine Response to Colour
Change(hrs)
Colour Change(hrs) QC(hrs)
Total
(hours)
4 8.5 0.47 0.53 9.5
10 3 0.4 0.6 4
12 0.82 0.56 0.75 2.13
7 0.48 0.62 1.07 2.17
20 2.17 0.83 5.37 8.37
8 0.37 1.1 0.43 1.9
87 2.25 0.51 0.49 3.25
10 5.53 0.47 0.25 6.25
20 0.26 1.23 0.76 2.25
75 8.02 0.73 1.28 10.03
74 0.55 2.58 1.2 4.33
87 11 0.78 1.22 13
20 10.35 1.25 0.4 12
7 15.45 0.17 1.38 17
12 18.97 0.86 0.17 20
74 5.43 1.15 1.42 8
75 1.56 0.76 1.13 3.45
3 1.35 0.82 0.25 2.42
Total 96.06 15.29 18.7
Average 5.34 0.85 1.04

3. Colour Change Duration
0
5
10
15
20
25
4 10 12 7 20 8 87 10 20 75 74 87 20 7 12 74 75 3
Machine
Time(hrs)
QC(hrs)
Colour Change(hrs)
Response to Colour
Change(hrs)
From looking at the figures it becomes clear where the problem is, responding to the
colour changes. The reason that the setters take too long to respond to these colour
changes is they are busy at other machines which makes them to neglect the idle
machine.
4. Conclusion
Looking at how frequent these colour changes come, I took the average number of colour
changes for the month of February. The cost service is indirectly proportional the waiting
line cost, which is why I used the waiting line cost theory to illustrate my point. The
optimal cost is found where the two graphs intersect. Some of the values used are not
true.
Plastop Waiting Line Cost Analysis
Number of Setters on shift 1 2 3 4 5
Average number of Colour change/shift 2 2 2 2 2
Average time each machine waits to be serviced 8 6 4 2 1
Total Colour change hrs lost per shift 16 12 8 4 2
Estimated cost per hour of idle machine time in Rands 100 100 100 100 100
Value of machine's waiting cost 1600 1200 800 400 200
Setter salary or service cost(At R25/hour) 200 400 600 800 1000
Total expected cost 1800 1600 1400 1200 1200

4. Queing costs and service level
0
500
1000
1500
2000
1 2 3 4 5
Service level
Cost
Cost of waiting Cost of providing service Total expected cost
5. Recommendation
I believe that we should work with the setters we have now. The problem is that they
cannot attend to colour changes quickly because they are caught up in other machines. If
we can make sure that when the machine starts running production that the quality
inspectors work with the setters in order to make sure that the machine continues running
the correct and good quality product. We then make sure that the settings are recorded for
future reference when running the same colour. When the machine is running then the
setters can concentrate on the mould and colour changes.
08 March 2009
Tshepo Makgakge
Industrial Engineering Trainee
Clock no.: 368