Using Pin Gages as a Measurement Tool for Ppk/Cpk studies

Re: Gages used for ppk/cpk studies

ScottK said:

in process we do "measure" with them because it suits our needs.

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1) The blade on a caliper is approximately 0.025 wide so you have already created a chord rather than a flush measure.

2) Your diameter is small enough (1.2mm) that only about 0.025 of the caliper blade tips can be used, very tricky measure.

3) The diameter is also small enough that the caliper tips will never be in line, you will always be measuring off center.

You simply cannot get as good a measure with a caliper; vernier, dial or digital, as you can with gage pins. Besides, it is always best to do your studies with the gages that will be used in production. (See PPAP Manual)

I used to be product engineer where they made spark plugs; it was a screw machine operation. The metal part of the spark plugs have an ID that the ceramic part sets into. The ID only ranges about 0.008. I had round cores with all increments of the pin gages inserted around the OD, made for variable gaging. Worked like a charm. Each gage looked like a pin wheel but everything was right there in one gage.

Make a gage or do something to "show and tell' your customer. They just have to be convinced.

There is the key..."it suits our needs." Your customers may be thinking, right off the bat, without really thinking, of the typical way a pin gage is used; you know, go-no/go. But if you use every increment from one limit to the other you have variable data. Its the same as the little increments on a dial caliper; better than a dial caliper.1) The blade on a caliper is approximately 0.025 wide so you have already created a chord rather than a flush measure.2) Your diameter is small enough (1.2mm) that only about 0.025 of the caliper blade tips can be used, very tricky measure.3) The diameter is also small enough that the caliper tips will never be in line, you will always be measuring off center.You simply cannot get as good a measure with a caliper; vernier, dial or digital, as you can with gage pins. Besides, it is always best to do your studies with the gages that will be used in production. (See PPAP Manual)I used to be product engineer where they made spark plugs; it was a screw machine operation. The metal part of the spark plugs have an ID that the ceramic part sets into. The ID only ranges about 0.008. I had round cores with all increments of the pin gages inserted around the OD, made for variable gaging. Worked like a charm. Each gage looked like a pin wheel but everything was right there in one gage.Make a gage or do something to "show and tell' your customer. They just have to be convinced.