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This thread is carried over and continued in the Current Elsmar Cove Forums
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The New Elsmar Cove Forums
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 The New Elsmar Cove Forums
 APQP and PPAP
 spc
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NeilM Lurker (<10 Posts) Posts: 5 |
posted 05 December 2000 12:14 PM
   
We are an injection moulding and metal pressing company supplying 1st automotive suppliers. As a result of a recent QS9000 audit i have been asked to re-look at the entire SPC strategy as to its applicability in supporting process controls (mainly process parameter control, First off, patrol inspection etc) and reviewing what is sensible industry practice. I am currently concentrating mainly on new product introduction - What are other similar organisations doing ? IP: Logged |
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Howard Atkins Forum Wizard Posts: 202 |
posted 05 December 2000 11:47 PM
You have got me on my high horse now. IMHO the demands for SPC in QS are antedeluvian and refer to process that are controllable and are given to immediate detection. Most SPC is on the part and not on the process. I experimented with finding parameters of injection molding that can be charted but in most cases this was not possible. If you are using closed loop machines then they corrct themselves. The only real parameters that are worth checking are total cycle time and plastification time. As plastic shrinks to measure dimensions immediatley means extrapolation of the shrink and thus measurement of the "wrong" dimension. I have persuaded customers that this is irrelevant to the spirit of the Standard. Weight is a parameter that could be used but it needs to be changed according to the density of each lot of material. For PPAP I submit a PPK number based on the measurements of samples 24 hours after production. This is acceptable. I hope that this helps you for further information please return. IP: Logged |
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Sam Forum Contributor Posts: 244 |
posted 06 December 2000 08:32 AM
I agree with Howard. I have tried several different methods for applying SPC to the injection molding process. For the same reasons Howard cited I too have reverted to dimensional measurement and/or testing to satisfy the requirement. "For PPAP I submit a PPK number based on the measurements of samples 24 hours after production. This is acceptable." This is the same criteria that I have used and have found it to be adequate, in that most materials haved "cured" within this time frame. Ford requires on-going SPC to monitor the dimensional and test results and this method satisfys them when noted in the control plan. IP: Logged |
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Sam Forum Contributor Posts: 244 |
posted 06 December 2000 08:34 AM
I agree with Howard. I have tried several different methods for applying SPC to the injection molding process. For the same reasons Howard cited I too have reverted to dimensional measurement and/or testing to satisfy the requirement. "For PPAP I submit a PPK number based on the measurements of samples 24 hours after production. This is acceptable." This is the same criteria that I have used and have found it to be adequate, in that most materials haved "cured" within this time frame. Ford requires on-going SPC to monitor the dimensional and test results and this method satisfys them when noted in the control plan. IP: Logged |
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