Waste elimination is usually among the simplest and most profitable targets for any cost reduction program. In fact, in setup and cycle time reduction workshops, we often find that the largest single improvement to a company's CNC environment has nothing to do with programming, setup, program verification, first workpiece inspection, maintaining production or any other CNC-related task. Instead, we usually find so much waste that the setup time reduction program is postponed until the waste is eliminated.
We define waste as any action (or inaction) that detracts from the most efficient utilization of CNC machine tools. While this broad definition encompasses a wide range of potential violations, it makes waste very easy to spot. And once you find waste, it usually doesn't take a rocket scientist to figure out how to eliminate it. Eliminating waste usually requires nothing more than a little common sense.
The first step to eliminating waste is accepting the fact that you probably have it. If you doubt that waste exists in your shop, consider that scrapped workpieces, crashed machines, excessive tooling costs, late deliveries, and inconsistency of any kindin cycle time, in setup time, in quality, in tool life, and so onare all symptoms of waste.
The best way to spot waste is to watch your people. In our setup and cycle time reduction workshops, we find the best way to watch people is to video-tape them performing their normal duties. Remember that people tend to work a little faster when they know they are being watched, meaning your video tape will render the best possible condition. In the real world of daily activities, your people will probably work at a slower pace.
One Typical Scenario
It is a natural human tendency to feel pride in your current methods. Unfortunately, pride can stand in the way of recognizing potential improvements. In fact, it may keep you from even accepting the possibility that potential for improvement exists. For this reason, we'll give a simple example. Pick a setup your setup people make on a regular basis (waste should be at its minimum when people are performing familiar tasks). Let your setup person know you'll be video taping, and make sure to tell him to work in the normal manner (so, of course, he'll work faster than normal).
The first time you video tape a setup, you will typically notice that your setup person disappears for long periods of time. It is likely that he or she is searching the shop to find hand tools, cutting tools, fixtures, gages or other materials needed to make the setup. This, of course, indicates that the person was not truly ready to make the setup in the first place. Depending upon the application, most companies consider time spent searching the shop while a CNC machine is down as very wasteful indeed.
Whenever a person must perform the same tasks over and over again, strive to ensure that their efforts are not wasteful. One common improvement involves cutting tools. There are many repeated tasks related to the assembly, measurement, and offset entry for cutting tools. If your setup person is not given guidance on to how these tasks should be done, you cannot expect that they are performing these tasks in the most efficient way.
More To Look For
It doesn't take a time and motion person to recognize wasteful duplication of effort. As you watch your setup people, for example, you may find that they are measuring the location of program zero even though the setup is qualified. If a setup is truly qualified (it can be accurately repeated over and over again), there should be no need to measure the program zero location during setup. This action should be seen as wasteful.
Mistakes will be made if your people do not know what it is you expect them to do and should be taken as a signal that documentation is not adequate. Mistakes, of course, are very wasteful, since they lead to duplication of effort, scrapped workpieces, crashed machines (downtime for corrective maintenance is very wasteful) and potential for injury.
Though this short discussion focuses on setup time reduction, you can easily target other areas of your CNC environment for a waste elimination program. Do so based upon your own company's needs. Remember, those companies that have never thought about their waste usually have the most!blog comments powered by Disqus