Supplier Using Reference Part for PASS/FAIL Inspection

[Ironcountry]

I recently discovered a defective part at receiving inspection only to find out that the supplier was using a mating part for pass/fail inspection, in my experience using mating parts for inspection has always been taboo.

I am looking for a documented standard or rule (if there is one) that outlines what equipment, gages, or fixtures would be considered as acceptable for pass/fail inspection.

 

[Jim Wynne]

I recently discovered a defective part at receiving inspection only to find out that the supplier was using a mating part for pass/fail inspection, in my experience using mating parts for inspection has always been taboo.

I am looking for a documented standard or rule (if there is one) that outlines what equipment, gages, or fixtures would be considered as acceptable for pass/fail inspection.

There is no such thing that's universally applicable and there's nothing inherently wrong with using a mating part to verify its counterpart. Was the fact that the part was bad related to the inspection method?

 

[Ironcountry]

The part didn't meet print and using a mating part that isn't quantified or in the calibration system = slippery slope, I would never do it especially when there are more acceptable options available.

 

[Jim Wynne]

The part didn't meet print and using a mating part that isn't quantified or in the calibration system = slippery slope, I would never do it especially when there are more acceptable options available.

Back to my original question: was the nonconformity something that happened as result of the method in question? Do you have good reason to suspect that the method will result in something bad happening? You certainly have the right as a customer to ask for something more thorough, but such decisions generally shouldn't be governed by personal preferences.

In a similar vein, have a look at Note #8 on this (PDF).

 

[somashekar]

supplier was using a mating part for pass/fail inspection, in my experience using mating parts for inspection has always been taboo.

Was the mating part periodically validated by the supplier / or checked back with customer in the complete process of the supplier inspection methodology ?
What is a mating part today may not be so on prolonged use. So it must be periodically checked (period to be decided scientifically) and agreed with the customer.

 

[Ironcountry]

The fact that the part failed was not related to the inspection method. I believe that note 8 on the drawing is not precise enough to interpret that inspection with the mating part is acceptable. Regarding the questions from the above e-mail, the rejection was from the first production lot so at this point I don't know.

 

[Claes Gefvenberg]

I recently discovered a defective part at receiving inspection only to find out that the supplier was using a mating part for pass/fail inspection, in my experience using mating parts for inspection has always been taboo.

I would frown at using a mating part, but if your specification allows for Maximum Material Condition (MMC), your customer could use a proper function gage instead. I assume that would make life a lot easier for you as well as the supplier?

/Claes

 

[True Position]

You are under no obligation to accept non conforming material even if it would fit the assembly and possibly function. Most likely your customer didn't want to scrap a number of finished parts so they checked them to your mating part and hoped you wouldn't find it at incoming or in assembly.

 

[somashekar]

The fact that the part failed was not related to the inspection method. I believe that note 8 on the drawing is not precise enough to interpret that inspection with the mating part is acceptable. Regarding the questions from the above e-mail, the rejection was from the first production lot so at this point I don't know.

Your part CTQ (Critical to Quality) and inspection requirements must have to be discussed prior to your approval of your part from this supplier. My suggestion is to work back with the supplier more closely and develop him to meet your requirement. If you OR the supplier must provide and make use of some gauge for inspection, it must be defined in advance and be available after due verification. It is not a sin to use mating part for inspection, but that method must have adequate control.
It is a classic case of control over outsourced process.