Increasingly, flexible manufacturing systems are being employed to allow the same equipment to produce a variety of different products, depending on demand. The key to the economic success of these systems is keeping changeover time to a minimum. Short changeover times mean more average production per hour and a smaller economical lot size. The time spent changing over a machine is part of what is called planned downtime. Planned downtime, if left unmanaged, can become a real sap on overall productivity.
One of the most common operations in flexible manufacturing machine setup is size change. Sometimes it’s a simple matter of moving a fence or a gate to a new detent or pin location. In other installations, a manual hand crank with a mechanical pointer and scale are used. Instead of a pointer and a scale, sometimes a mechanical counter is used (looks like an old-style automobile odometer). The benefit of a manual, human-powered (and controlled) system is simplicity and low-cost. The downside is reliance on the human element to repeatedly and reliably make the correct adjustment for the particular product being run. If the adjustment isn’t correct, the result could be a costly, wasteful jam or worse: machine damage leading to unplanned downtime and repair expense.
In more sophisticated operations, size change might be an automated process using an electric servo system. Although this certainly gets the job done, in a lot of cases it is technical overkill as well as a potential budget-buster.
Next month, we will explore alternatives to low-cost yet unsophisticated manual size change mechanisms, and high-performance yet costly servo-driven size-change systems.
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