A certain job shop specializes in one-of-a-kind orders dealing with parts of medium-to-high complexity. A typical part is processed sequentially through 10 machines in batch sizes of 1. The shop contains a total of eight conventional machine tools and operates 40 hr/wk of pro duction time. Average time values on each part per machine are: machining time = 0.5 hr, work handling time = 0.3 hr, tool change time = 0.2 hr, setup time = 3 hr, and non operation time = 12 hr. A new programmable machine is being considered that can per form all 10 operations in a single setup. The programming of the machine for this part will require 20 hr; however, the programming can be done off-line, without tying up the machine. Setup time will be just 2 hr because simpler fixtures will be used. Total machining time will be reduced to 80% of its previous value due to advanced tool control algorithms; work han dling time will be the same as for one machine; and total tool change time will be reduced by 50% because tools will be changed automatically under program control. For the one machine, nonoperation time is expected to be 12 hr, same as for each conventional machine. (a) Determine the manufacturing lead time for the conventional machines and for the new programmable machine. (b) Compute the plant capacity for the following alternatives: (i) a job shop containing the eight traditional machines, and (ii) a job shop containing two of the new programmable machines. Assume the typical jobs are represented by the data given above. (c) Determine the average level of work-in-process for the two alternatives in part (b), if the alternative shops operate at full capacity
A certain job shop specializes in one-of-a-kind orders dealing with parts of medium-to-high
complexity. A typical part is processed sequentially through 10 machines in batch sizes of 1.
The shop contains a total of eight conventional machine tools and operates 40 hr/wk of pro
duction time. Average time values on each part per machine are: machining time = 0.5 hr,
work handling time = 0.3 hr, tool change time = 0.2 hr, setup time = 3 hr, and non
operation time = 12 hr. A new programmable machine is being considered that can per
form all 10 operations in a single setup. The programming of the machine for this part will
require 20 hr; however, the programming can be done off-line, without tying up the machine.
Setup time will be just 2 hr because simpler fixtures will be used. Total machining time will
be reduced to 80% of its previous value due to advanced tool control algorithms; work han
dling time will be the same as for one machine; and total tool change time will be reduced
by 50% because tools will be changed automatically under program control. For the one
machine, nonoperation time is expected to be 12 hr, same as for each conventional machine.
(a) Determine the manufacturing lead time for the conventional machines and for the new
programmable machine. (b) Compute the plant capacity for the following alternatives: (i) a
job shop containing the eight traditional machines, and (ii) a job shop containing two of the
new programmable machines. Assume the typical jobs are represented by the data given
above. (c) Determine the average level of work-in-process for the two alternatives in part
(b), if the alternative shops operate at full capacity
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