Question: Given your answers to Problem 11.21, the costs of both carousel systems arc to be compared. The one-carousel system has an installed cost of $50,000, and the comparable cost of the two-carousel system is $75,000. Labor cost for a picker-operator is $20/hr, including fringe benefits and applicable overhead. The storage systems will be operated 250 day/yr for 7 hrs/day, although the operators will be paid for 8 hr. Using a 3-yr period in your analysis and a 25% rate of return, determine:

(a) the equivalent annual cost for the two design alternatives, assuming no salvage value at the end of 3 yr; and

(b) the average cost per storage/retrieval transaction.

Problem: A carousel storage system is to be designed to serve a mechanical assembly plant. The specifications on the system are that it must have a total of 400 storage bins and a throughput of at least 125 S/R transactions/hr. Two alternative configurations are being considered:

(1) a one-carousel system and

(2) a two-carousel system.

In both cases, the width of the carousel is to be 4.0 ft and the spacing between carriers = 2.5 ft. One picker-operator will be required for the one-carousel system and two picker-operators will be required for the two-carousel system. In either system vc = 75 ft/min. For the convenience of the picker-operator, the height of the carousel will be limited to five bins. The standard time for a pick-and-deposit operation at the load/unload station = 0.4 min if one part is picked or stored per bin and 0.6 min if more than one part is picked or stored. Assume that 50% of the transactions will involve more than one component. Determine:

(a) the required length and

(b) corresponding throughput rate of the one-carousel system and

(c) the required length and

(d) corresponding throughput rate of the two-carousel system.

(e) Which system better satisfies the design specifications?