What is Poka-yoke? By definition, it’s the implementation of fail safe mechanisms to prevent a process from producing defects. It’s a pretty simple concept. Error proofing becomes a method of 100 percent inspection at the source, rather than down the line.

That’s a little bit misleading the way I stated that, because what we want to do with error proofing and improvement of the predicability is reduce the actual inspection that takes place because that is non-evaluated time in the manufacturing process. Each process hand off must be a perfect product for the next downstream process.  That’s what we want to get to by implementing effective error proofing. 

Now, some real-world examples of Poka-yoke—the break and shift interlock on your car or the automatic transmission to prevent starting the engine. Unless you have it in park or on a manual shift and most of you have the clutch in, the software of the automobile will not allow you to start that engine. That’s a Poka-yoke process right there. The old hanging a tennis ball from the garage ceiling so that when it taps your windshield on the way in and you know when to stop the car in the garage, that’s also a Poka-yoke method. The childproofing caps on medicine bottles that have been around forever are preventing an error. The speed dial on a cell phone is there so that you can reduce the time it takes to dial a number and eliminate the error of pushing the wrong button. These are all common everyday occurrences of Poka-yoke. 

We want to take similar approaches in the manufacturing process to eliminate errors there. Everybody is familiar with the bar coding of like components to distinguish the differences. There is bar code scanning at your checkout line at the grocery store. It speeds up the process, eliminates the errors of entering the wrong data and cost on every purchased item. There are torque limiters on assembly tools, so you don’t over tighten the bolt. All of these are industry examples of Poka-yoke.

Now in this presentation from this point on we will get to specific things that we can do in the manufacturing process that would fall under the category of error proofing, or Poka-yoke.  Some of the things I’m going to look at and discuss with you this morning include program simulation for crash avoidance (this is in the programming stage) and fixture considerations. We’re going to look at different techniques that might be used. There is tool setting automation, or how to eliminate the risk of the machine controls. There are tool condition monitoring and safe programming considerations.

There are some things that we do here at Makino in a lot of our turn key work with error proof programs and safe programming considerations.  Then also, of course, machine monitoring methods that can be used and applied to reduce error in the manufacturing process in the actual machining process.