There are considerably more opportunities to improve efficiency than to reduce a tool’s cycle time. All too often, manufacturing companies invest hundreds of thousands of dollars in new machine tools to increase production, or countless hours testing tools to take 30 seconds out of an operation, when they could accomplish more dramatic results with existing machinery at a fraction of the cost.

At BIG Kaiser Precision Tooling, our customers are demonstrating a significant trend toward reducing the setup time involved in a machining operation. We have found that many machines cut metal less than 50 percent of the time during working hours and even less in flexible manufacturing environments where part runs are generally short. For the rest of the time, these machines sit idle while their operators are setting up fixtures and tools for the next operation.

Some shops, unaware of the capabilities and cost efficiency of today’s off-line tool presetting equipment, have dismissed off-line adjustment as an extravagance. However, setting up tools on a machine tool essentially means using the machine tool as a “presetter”—a very expensive presetter. For example, consider a shop running four CNC mills for two shifts per day at a shop rate of $40 per hour. If each operator takes only 1 hour per shift on each machine for tool setup, the shop is losing about $320 per day, or $83,200 per year, to spindle downtime. If this setup time isn’t sufficient to ensure optimal cutting conditions, short tool life and scrapped parts will quickly erode profits.

Many manufacturing operations go the traditional route of keeping a central tool crib and letting each machinist more or less fend for himself, gathering tools and then going back to his machine to execute the setup. We are seeing a significant shift by our customers toward a much more streamlined method. The crib attendant, who only managed inventory before, is being replaced with a skilled machinist who understands how and when each job is going to run. Now the new crib attendant gathers the proper fixtures and kits the tools for each job, measuring each tool tip off-line. This way, fixtures and tools are gathered and offsets are established while the machine tools are still “in-cycle” before machinists begin their setups. That is saving a huge amount of time. During the reduced setup time, part programs as well as tool offset data are downloaded directly into the machine control, reducing even further any possible human error.

The heart of the problem with the old way of doing things is that responsibility for getting fixtures and tools together for a job rested entirely with the machinists, and that simply has them spending too much time scrounging around the shop for everything they need to get a job up and running. When the machinist finally does locate everything he needs, each one of those tools has to be loaded into the machine and touched off manually to establish the initial tool offsets. Searching for and then setting the location of fixtures also significantly complicates a process that modular quick-change workholding rapidly solves. After all that time has elapsed, trial parts have to be carefully cut and closely examined to make sure the setup was ready for production.

Many of our customers have found that routine use of modular workholding systems and off-line tool presetting equipment significantly reduces spindle downtime and keeps their machine tools producing quality components. Off-line adjustment of boring bar length and diameter can reduce tool change-over time at the machine from 15 minutes to less than 1 minute. On CNC lathes, similar reductions in setup times are routinely achieved. With tools that require a length-only setup, shops can realize a reduction in setup time from 5 minutes to less than 1 minute per tool.

In the plan that we are advocating, responsibility for all fixture and tool preparation work for setups can be shifted to the tool crib, including the off-line establishment of individual tool offsets. This, of course, would require a new level of capability in the crib, including someone who understands the machining process as well as setup procedures. It would also require the acquisition of a precision tool presetter for the highest level of precision and repeatability in tool setups. No on-machine touch-offs, no trial parts—only total, first-part precision.

As for the financial ramifications, there is little question that better management of setup time through modular fixtures and off-line tool setup has added significantly to the user’s bottom line.

Richard E. McCarthy is the national sales manager, tool measuring systems,
at BIG Kaiser Precision Tooling Inc. He can be reached at (847) 228-7660.