Integral Logistics Management — Operations Management and Supply Chain Management Within and Across Companies

13.4.2 Operation Overlapping and Overlapping Within an Operation

Intended learning outcomes: Explain te principle of overlapping within an operation. Describe the principle of operation overlapping.



We speak of overlapping within an operation when the individual units of a lot are not produced sequentially, or one after the other, but rather overlap one another.

Consider the example of an assembly operation for machines. The operation may comprise several partial operations. Figure 13.4.2.1 shows the situation for the lot as a whole.

Fig. 13.4.2.1       The principle of overlapping within an operation.

A later partial operation on the first machine of the lot may be worked on parallel to the first partial operation on a subsequent machine of the lot.

The run time offset, or offset of the next run time, is a measure for the overlapping within an operation.

Run time offset is expressed as a percentage of run time. The standard value for run time offset is 100%, or “no overlapping.”

For some production processes, you can overlap entire operations.

In an operation overlapping or an overlapped schedule, we begin the next operation on a portion of the lot before the entire lot is completed with the previous operation.

Figure 13.4.2.2 shows an example. Schedulers can use operation overlapping to accelerate a production order.

Fig. 13.4.2.2       The principle of operation overlapping.

The maximum offset of the next operation is a measure of operation overlapping. It is based on one operation and shows the maximum lapse of time before the next operation begins.

In practice, the next operation begins immediately after the setup time and run time for the first unit (or first units) of the order lot. (See, for example, near-to-line production in Figure 6.2.2.2).

The initial value of the maximum offset of the next operation is infinite, that is, “no overlapping.” If the time we calculate (based on operation time and inter­operation times) until beginning the next operation is smaller than the actual value, we take the smaller time as the new offset time.




Course section 13.4: Subsections and their intended learning outcomes