Electric terminal crimping machines - Is SPC appropriate for this process?

ARC05

Starting to get Involved
#1
G'day all,
We use electric terminal crimping machines in production, crimping small automotive style terminals/pins to wires, e.g. 20 awg. Typically no more than 100 crimps per day per machine.
Every morning, and each time a terminal reel is changed, each machine is verified and calibrated using pull force testing on sample crimps.
- If the result is PASS and >~15% above minimum spec, no adjustments are made,
- If result is PASS and within 15% the settings will be adjusted, retested and then commissioned for use,
- If the result is FAIL, QA Manager is notified and we would investigate cause as well as impact to items produced.
Test results are maintained in hard copy as records.

Question - is SPC appropriate here, and if so how would it help? I figure not due to the daily verification testing. Each time a machine is recalibrated the results are independent of the previous one.
Open to ideas...
Thanks
 

AgnieszkaSz

Quite Involved in Discussions
#2
To make this clear - do you want to assess the press, or the applicator, or the process (specific applicator working with specific press)? I gather that the variable will be the crimp height. From my practice - this was done for specific applicator; we used to perform series of 100 samples after each 40.000 crimps and measure all samples. The results should be within tolerance range for particular terminal type, but you can calculate Ppk as well.
 

ARC05

Starting to get Involved
#3
Hi @AgnieszkaSz thanks for your reply. Sorry I wasn't clear - I don't actually see any need for further analysis / assessment personally. We have daily pull force verification tests for each crimp machine, so I the risk of non-conforming crimps is very low. As I mentioned we do very low volumes.
Background is a 'finding' from a customer audit which says we should be should be using SPC to "monitor consistency and accuracy". So my question was simply whether anyone here can see benefit in exploring any SPC methods in this situation?
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#4
You can only use attribute SPC on that type of data. The only variable data from crimping is crimp height, and that data could identify a dies so worn it needs replaced. Not much else will give you valuable SPC data - especially pull-to-failure.
 

optomist1

A Sea of Statistics
#5
Using continuous or variable data will provide insight as to the direction the crimping process is headed...possibly tooling issues, set up issues etc...much is dictated by your customers specs and acceptance criteria....below is a link to a supplier of tensile test equipment used to perform pull out tests...another more involved and expensive method is to section and examine crimped wire terminal connections....hope this helps


Force Gauge, Torque Gauge, Spring Tester, Pull Tester, Peel Tester Measurement - Mark-10
 
Top