Long setup times are still a reality in many companies. Setup is one of those activities that adds no value to a part and, therefore, needs to be as short as possible.
Before discussing ways to reduce setup time, it is important to define what we mean by the term. I have found the best definition for setup time to be the total time from the last good piece of one job to the first good piece of the next job. This includes teardown, preparation, and the actual loading of parts, tools, fixtures, and possibly even programs on the machine. We need to count all of these activities as setup so we have a consistent starting point from which to improve.
Obviously, the best setups are no setups (or changeovers), but in those cases where it is necessary to change over a machine from producing one part to another, here are some ideas that might help you.
1. Keep frequently used tools in the machine. It is likely that you use some tools repeatedly from job to job. Take a look at tool lists for your most frequently run jobs and see if anything stands out. In my experience, there are usually common spot or center drills, end mills and perhaps even drills or boring bars. Of course, if you are going to keep a certain number of tools in the machine, you'll need a procedure for reviewing and maintaining their condition.
If you find there is no tool commonality between jobs, perhaps you should review your machining processes and make a conscious effort to standardize tooling whenever possible.
2. Improve organization of tooling. A lot of setup time is really "search time." Operators search for tools in cabinets, on shelves or in cluttered drawers. These storage devices are not conducive to storing tools and should be replaced by horizontal drawer tool cabinets with easily configurable dividers. All dividers should be clearly labeled, enabling anyone to locate items quickly.
3. Use sub-plates on machine tables. Sub-plates, which are plates with a series of holes spaced at predetermined intervals, are an effective means of assuring repeatable positioning of fixtures. Holes on the sub-plates should be engraved to provide quick identification. Setup records should then indicate which holes to pick up when positioning fixtures used on different jobs.
4. Simplify fixtures. Use self-aligning or self-centering fixtures to eliminate manual locating and positioning when possible.
5. Prepare all paperwork in advance, and review it to assure accuracy and completeness before getting material, tooling or fixtures. This simple step can save hours of machine downtime during setups. Often, we find incomplete information hindering our setup efforts.
6. Preset tools off-line whenever possible. This also includes inspecting the tools to be sure that they are in the proper condition. The best type of tool presetter downloads tool dimensions directly into the machine's control, eliminating the need to load this information manually.
7. Don't skimp on tools and toolholders. Be sure there are enough tools available to prevent delays in setup. Compared to the cost of machine downtime, tools are still a bargain.
8. Take steps to eliminate dry runs or machining of setup pieces. The time to dry run, or machine setup pieces, can be significant. If operators are not comfortable running a job without these "insurance steps," find out why. Typically, operators may lack confidence in a CNC program or have concern about the condition of tools, toolholders or fixtures. If this is the case, steps must be taken to alleviate these concerns through a formal system to ensure accuracy and reliability of everything an operator needs to run a job. Time invested up front will reduce setup time later.
9. Make use of air or electrically operated tools to reduce manual tightening and loosening of fixtures. Often we use manual ratchet tools, which can be both fatiguing and time consuming. Simple power assisted tools can reduce this fatigue and time. Be sure the tools have a torque-limiting feature to prevent over-tightening and resultant damage to threads.
10. Review and evaluate the role of first piece inspection. Often, the approval of first piece inspection is a major cause of setup delay. There are varying views of the need for formal first piece approval, especially on previously run jobs. Some companies insist that the second piece not be made until an inspector has signed off on the first piece. Others are willing to give the operator all the tools and equipment needed to assure a part is correct. Whatever approach you believe to be the best, you need to ensure that the first piece inspection process is not holding up the production of parts.blog comments powered by Disqus