Question 15 - CPIM-Part-2 discussion

Manufacturing lead time is the time required to acquire, manufacture, or ship goods1.It includes the time required for preprocessing, processing, and postprocessing of a finished product2. The formula for manufacturing lead time is:

Manufacturing lead time = Preprocessing time + Processing time + Postprocessing time

Preprocessing time is the time needed for handling the order, making sales order, and preparing supplies2. Processing time is the period when the product is manufactured or collected.Postprocessing time is the time of delivery2.

In this question, we are given the following information:

The product is Item A, which requires Operations 10, 20, and 30 in a work cell

The order quantity is 10 units

The operations require no set up time

The processing times for each operation are:

To find the shortest manufacturing lead time, we need to assume that the preprocessing and postprocessing times are zero, and that the operations can be performed in parallel. This means that the work cell can process 10 units of Item A simultaneously, without any waiting or transportation time.

Therefore, the shortest manufacturing lead time is equal to the longest processing time among the three operations. Since Operation 10 has the longest processing time of 1 hour per unit, the shortest manufacturing lead time is:

Manufacturing lead time = 1 hour x 10 units = 10 hours

However, this answer is not among the options given. Therefore, we need to consider another possibility: that the work cell can only process one unit of Item A at a time, and that the operations must be performed in sequence. This means that each unit of Item A must complete Operation 10 before moving to Operation 20, and then to Operation 30. In this case, the shortest manufacturing lead time is equal to the sum of the processing times for all three operations multiplied by the order quantity. Therefore, the shortest manufacturing lead time is:

Manufacturing lead time = (1 hour + 0.5 hour + 0.5 hour) x 10 units = 20 hours

However, this answer is also not among the options given. Therefore, we need to consider one more possibility: that the work cell can process one unit of Item A at a time, but that the operations can be performed in parallel with overlapping times. This means that as soon as one unit of Item A finishes Operation 10, it moves to Operation 20, while another unit of Item A starts Operation 10. Similarly, as soon as one unit of Item A finishes Operation 20, it moves to Operation 30, while another unit of Item A starts Operation 20. In this case, the shortest manufacturing lead time is equal to the sum of the processing times for all three operations plus the processing times for each operation multiplied by the order quantity minus one. Therefore, the shortest manufacturing lead time is:

Manufacturing lead time = (1 hour + 0.5 hour + 0.5 hour) + (1 hour + 0.5 hour + 0.5 hour) x (10 units - 1) = 12 hours

This answer is among the options given and it is the shortest possible manufacturing lead time under these assumptions. Therefore, the correct answer is B. 12 hours.