Process control - Finished product vs. Tooling



We are trying to implement process control on our production line and we have a lot of different view of what we should do.
First, brief introduction of the company; We are a rubber molded and/or extruded supplier (QS-9000) for the automotive Industries. Our PPM at customers facilities are less than 100 and we grow fastly (500 employees, 6 plants, 2 technical centers).
Second, we want to keep the system as simple as possible for every one (doing less than what we are doing right now is better!).
Third, we make more than 100 similars products (like sausages, but differents size, shape and ingredient)
In the moment, our opinion on spc is: we want to certified our finish product by certifying the toolling. Exemple: If a die cutter is use to cut our part, the die won't change in the near future( maybe wear a little but not that much), so the length will always be the same over time. Instead of doing continous monitoring (like spc) can we certified (or calibrate) our tooling (those which always do the same kind of job) once a month or once a year and make monitoring of the process once a day or once a week? After that we thing be able to fix the process tolerance with CPK (ex: If the customer tolerance are +/-1, be able to say that the CPK will be higher than 3)

Is this thinking right?


If you say that you have identified tooling as the predominant cause of variation, and are trying to control your process by certifying tooling, this likely an acceptable approach.

You can do almost anything to "certify" your product, as long as there is evidence that the product is certifiable. Tooling does change, pressures and temperatures and feed rates can be adjusted, all of which adds to the process variation. As long as you have identified these, know and understand the extent of the variation these changes make, and can prove that all the present process inputs that are responsible for the variation are under control, then certifying the tooling is one way to assure quality.

Don Winton

Batman pretty much covers it. Define the key input variables, define the extent of control over these variables and carry on.


Just the ramblings of an Old Wizard Warrior.
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