TS 16949 Clause 7.5.1.3 - Statistical Methods of Verification of Job Set-ups

[rickmcq]

In regards to job set-ups the element says "The organization shall use statistical methods of verification, where applicable."

Statistical methods of what? The job doesn't run until QC verifies the first part off of a set-up is correct and the inspection is recorded. I don't understand what is being required here.

Rick

 

[Jen Kirley]

Hi Rick,

You're right that initial setups won't have the SPC going yet. In many places, contract manufacturing for example, a job changeover would also probably need new capability studies. The process must be made capable, then SPC can monitor its ongoing continuity.

But notice that in the clause included mention of material change, which may happen in the middle of some runs: changing chemical baths, for example. In a CNC machine we may need to change a cutting bit when it's worn. That shouldn't be a reason to redo the capability study. We should be able to do that without triggering a serious blip in the SPC chart.

The clause is confusing because it combines initial setup with material changes. But it says "where applicable," so you decide.

I hope this helps!

 

[vanputten]

SPC is one type of statitical method. Analyze the variation in the data over time that is collected at set up.

 

[rickmcq]

Hi Rick,

But notice that in the clause included mention of material change, which may happen in the middle of some runs: changing chemical baths, for example. In a CNC machine we may need to change a cutting bit when it's worn. That shouldn't be a reason to redo the capability study. We should be able to do that without triggering a serious blip in the SPC chart.

The clause is confusing because it combines initial setup with material changes. But it says "where applicable," so you decide.

I hope this helps!

Yes, it is confusing. Data is being collected and analyzed all of the time through several of the other requirements. Your examples would be looked at in the monitoring of processes/product and even continual improvement.

But the title of this element is Verification of Job Set-ups. Job set-ups are always verified through first piece inspections which include correct grade of material, etc.. I still do not understand what the set-up data would contain that a customer, third party auditor or management would expect to be seeing.

How many times did the first part fail an inspection maybe?

Rick

 

[vanputten]

When one applies SPC to the manufacture of something, it has to start somewhere. SPC starts when we begin to collect data. So begin to collect data on the set up process parameters that are meaningful in understanding the variation and effectiveness of the set up.

"Set ups" are a process. SPC and statistical methods can be applied to any process. Just because the "job" hasn't started yet in terms of traditional manufacture, a process is running. This process is called "set up" and the standard is requiring users to use statistics, where applicable, to understand the effectiveness and variation of the set ups. The intent here is that if the variation and the effectiveness of the set ups is understood and controlled, then the "job" will produce product that meets requirements more often.

This is the Process Approach as applied to the process of Set Ups.

One could look at the variation in set up time, first pass success, variation in any variable data that is collected at set up, etc. Do you want to know how effective the set up is the first time? What if set ups were not approved on the first try and in general it takes 3 tries to get a set up approved? Does the initial output of the set up, which is used to approve the production job, meet requirements? How often? How much variation from the mean or target value? How does the variable data that is collected vary within the control limits? Is the data always above the target value? Below? Is there drift over time in the data collected? Can you prevent nonconforming material by understanding the variation over time of the data collected at start up? Sure!

If the data is an attribute and not variable, you could use a n, np, u or c chart to understand the variation in the attribute.

Side note: I never understood why using any statistical method like a bar chart or a pie chart to control a process is not "SPC." Some say that these statistical techniques are not necessarily "SPC." Maybe it is because one can use a statistical technique like a bar chart for things other than trying to control a process. And maybe when one applies any statistical technique or method to controlling a process it is "SPC." Anyway, 7.5.1.3 requires the use of statistical methods which may or may not be traditional SPC.

 

[Sturmkind]

David Bothe's technique of Short-run SPC is applicable to proven set-up and material changeovers since one can record the observed variance of 1st piece submitted from the process target value for important parameters.

 

[rickmcq]

This is a very good reply. Thank you. I do think that data for some, but not all, of your examples is being collected and looked at. I have yet to jump into 7.5.1.3 due to not fully understanding it.

Thanks

Rick