Patent ID: 7343353

Claim:
A method for determining which of a plurality of machine tools to turn off during low production times for greatest operational cost savings with minimum fab cycle time increase, the method comprising: predicting said machine tools' utilization according to a demand forecast, said demand forecast projecting an amount of future product to be processed by said machine tools; calculating said machine tools' utilization according to a number of said machine tools that are turned off; calculating theoretical cycle times of said machine tools using an X-factor equation; selectively determining a change in said theoretical cycle times when one of said machine tools is turned off; calculating an operational cost savings versus said change in said theoretical cycle times by dividing a known monthly cost savings per tool when turned off by said change in said theoretical cycle times; using said calculated operational cost savings versus said change in said theoretical cycle times to determine at least one optimum one of said machine tools to turn off; and selecting one or more of said machine tools to turn off, wherein said selection is performed to maintain said fab cycle time under a predetermined maximum acceptable fab cycle time.