I have been in the Automotive world since 1996 and I'm very familiar with Cpk, XbarR, P-charts, etc... but I am now in the Aerospace/Defence industry and its very low Volume. I do not see any SPC being done in the process and their procedures and just window dressing for the SPC requirement in ISO.

What sort of SPC techniques can be applied in a low volume environment???
There is LOTS of inspection going on (First Piece and Final) but no SPC.

Please help....
Thanks,
ZeissUser

Hi
Depending on your volume you can either measure 100 % or you can measure 50 -100 pieces that you can calculate Cpk.
If you use Cpk you can set your index to 1.67 or even better 2.00.
/N :o

There are SPC techniques called "short run," in which the data is normalized (e.g., + or - amount off target). You might also look at PreControl techniques.

I didn't notice there were any SPC requirements in ISO 9001.

I did a Ford "short run SPC" course about 15 years ago. It seemed like a good idea at the time but now I have to question the validity of most of the SPC application I see.

The emphasis should be on Process Control. If the Xbar charts are just being used for decoration and are worked out in the manager's office at the end of the week then it is not "process control".

A run chart or just sample measurement is just as useful and easier for operators to do.

There are SPC techniques called "short run," in which the data is normalized (e.g., + or - amount off target).

Not normalization but scale the measurements according to the target and/or variation.

But insteed of using average and range you can use individual and moving range charts (it's like Mikes said about run chart but with limits). :agree1:

Or using Multiplevariable Quality Control (but the setup looks like a **** of work and data, and until now, I didn't found any good explanation on how to do it altho It uses PCA and relates the most important variables relationships on a simple chart). :bonk:

I added a file I found on the net about using low amount of data for managerial pourposes, this may help it's not for quality but it's interesting.

Thanks for all the Feedback. I'll try the techniques you mentioned although I think I like the RUN Chart Idea.

Thanks again,
Zeissuser

I have been in the Automotive world since 1996 and I'm very familiar with Cpk, XbarR, P-charts, etc... but I am now in the Aerospace/Defence industry and its very low Volume. I do not see any SPC being done in the process and their procedures and just window dressing for the SPC requirement in ISO.

What sort of SPC techniques can be applied in a low volume environment???
There is LOTS of inspection going on (First Piece and Final) but no SPC.

If you are doing precision machining as a low-volume process, the X-hi/lo-R char works with any number of parts. More importantly, is assures that all of the parts are in spec (at least based on common causes, not special causes like broken tools). For more info, check out:

Statistical process control for precision machining (http://elsmar.com/Forums/blog.php?b=79) :cool: