1. Unit Time 8/24/04 Paul A. Jensen
Operations Research Models and Methods
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2. Operation time depends on processing time and setup time
The processing time is the time required to process one unit of product
The setup time is the time to setup a machine for a single batch or lot of product

3. Different times for an operation:
The time to process one piece at the operation, the operation time.
The time used on the operation to produce one finished good, the unit time.
The total time for a production volume V.

4. Example Operation Unit Flow Time 1 1.929 1.0 2 1.736 2.0 3 3.086 0.5 4
1.389
0.3 5
5.879
0.4 6
5.291 7
4.762 8
1.111
1.2
Unit
Time
1.929
3.472
1.543
0.417
2.352
10.582
2.381
1.333

5. Example: Line with defects and inspectionu
1.88
Operation i 1 2 3 4 5 6
Oper. Time t
Unit Flow
Total Time = 50.76

6. Repeating an operation is called recyclingV C = p ( + )
Recycled amount: Vp
 1 - 
Total Flow:
(1 +
) =

7. Recycling with Scrap

8. Example: Line with defects and recyclingu 1
Unit Flow
Unit Time U
3.33
4.44
5.55
6.66
Total Time = 29.97

9. Alternative Designs

10. A complex flow routing

11. Analysis

12. Solution

13. An example with defects routed through the whole line