Example of capacity check
The Master Production Schedule is weekly. A production line is managed with KANBAN.
Opening Time between 2 MPS | Pause | Shutdown | Maintenance | Operating time |
3 shifts : 8 * 3 * 5 hours = 120 hours | 1 hour per shift, 15 hours per week | average 8 hours per week | 4 hours per week | 120 - 15 - 8 - 4 = 93 hours |
This line produces the following references: A, B, C, D, E, F, G, H.
Reference | Standard pack | MPS demand for the week Wk1 in pieces | Change over time in minutes | Real cycle time in seconds | Scrap rate |
A | 100 | 1000 | 20 | 12 | 0% |
B | 200 | 500 | 40 | 7 | 3% |
C | 100 | 3000 | 30 | 8 | 8% |
D | 100 | 7000 | 25 | 8 | 7% |
E | 100 | 15000 | 10 | 9 | 3% |
F | 100 | 500 | 7 | 10 | 2% |
G | 100 | 800 | 3 | 12 | 5% |
H | 100 | 600 | 3 | 7 | 3% |
Quick capacity check
At this stage of the sizing process we have to do a quick checking of the capacity. Do we have enough time to produce in one batch the MPS demand of each reference? This is the detailed calculation:
Reference | Change over time in minutes | Production time in minutes | Total time |
A | 20 | (Multiple of 100 for 1000 = 1000) * 12 / 60 | 220 minutes = 3.67 hours |
B | 40 | (Multiple of 200 for 500 = 600) * (1+0.03) * 7 / 60 | 112 minutes = 1.87 hours |
C | 30 | 3000 * (1 + 0.08) * 8 | 462 minutes = 7.7 hours |
D | 25 | 7000 * (1+0,07) * 8 | 1024 minutes = 17.06 hours |
E | 10 | 15000 * (1+0,03) * 9 | 2328 minutes = 38.79 hours |
F | 7 | 500 * (1+0,02) * 10 | 92 minutes = 1.53 hours |
G | 3 | 800 * (1+0,05) * 12 | 171 minutes = 2.85 hours |
H | 3 | 600 * (1+0,03) * 7 | 75 minutes = 1.25 hours |
Total time required to produce with one batch all references in order to cover the MPS demand: 74.72 hours. This time is lower than the operating time (93 hours) so we have the capacity to use a KANBAN system.
Scope definition
After the MPS review, 2 references A, B are showing a demand during next week only, so they will be not managed by KANBAN.
What is the time allocated to produce these references during the next week if we produce each of them in one batch?
We can use the previous calculation:
- Reference A: 3.67 hours;
- Reference B: 1.87 hours.
Total time required to produce MPS demand for the references not managed in KANBAN: 5.54 hours.
It remains 87.46 hours of available operating time to run KANBAN which is higher than the time to produce the demand of KANBAN references by one single batch. We have now to calculate the Batch size for each KANBAN reference.
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