Question: Consider a two step production process with rework. After completing both steps of the process, a quality check is performed, where 25% of the produced parts are found to be defective. Defective parts are sent back to be reprocessed on step 2. The processing time for rework on step 2 is the same as for new parts.
Processing a part on resource 1 (step 1) takes 6.1 minutes, processing a part on resource 2 (step 2) takes 6.0 minutes.
a) Assume that reprocessing is always successful. Find the capacity of the process (expressed in good parts per hour).
b) Next, assume that a part being reprocessed has again a 25.0% chance of being rejected at the final inspection at the end of the line. This rejection, however, is final: a twice rejected part must be scrapped.
Find the capacity of the processed (expressed in good parts per hour).