Question

Consider the following four--‐step assembly operation with quality problems.

-The first resource has a processing time of 7 minutes per unit and one employee doing the operation

‐ The second resource has a processing time of 4 minutes per unit.  It also has one employee doing the operation. However, this is a very delicate task and 0.79 of all products have to be scrapped after this step.

‐ Two workers are staffed for the third resource. No quality problems occur at this resource and the processing time is 17minutes per unit.

‐ At the fourth and final resource, one operator handles the product. No quality problems exist at this step and the processing time is 12 minutes per unit.

What is the process capacity per hour? (keep two decimal)

Answer 1

The time taken for 1^st process is: 7 minutes per unit

The time taken for 2^nd process is: 4 minutes per unit

• As .79 of all the products are scrapped
• .21 of all the products are passed to next process
• Therefore we can say .21 of product take 4 minutes
• So 1 product will take = 4/.21 = 19.05 minutes per unit

The time taken for 3^rd process is: 17 minutes per unit

• As there are 2 staff stationed so time taken for 3^rd process is: 8.5 minutes per unit

The time taken for 4^th process is: 12 minutes per unit

Now we can say bottle neck is process 2 which will define the capacity of the system

So process capacity per hour = 60/19.05 = 3.15 units