Question 4:

(Question 4 is in three parts: A, B, and C)

A. A fully automatic 4 station high speed assembly system operates on a cycle time of 7

seconds. It is fed with components having on average 2% defective components.

Approximately 80% of the defective components will cause the machine to stop and

on average it takes 30 seconds to clear a fault. The machine is required to produce

450 acceptable assemblies per hour on a production run basis. Calculate the 'down-

time' on the system due to defective components and comment of the feasibility of

achieving the target of acceptable assemblies. Justify any expression used in the

analysis.

(25 Marks)

B. Considering your answer to Part A, suggest ways of reducing down-time on assembly

machines caused by defective components.

C. If the system in part A is now fed components having on average 25% defective

components, what is the probability of making a defective assembly? Justify any

expression used in the analysis.