Control Plan Requirements - Should I identify all the individual drawing dimensions?

[madeyecol]

Hi All,

I am fairly new to control plans and would like some thoughts on control plan requirements with regard to product characteristics

I have performed a PFMEA on the manufacture of a fabricated component which undergoes a number of processes i.e. basically the blank is punched out from a sheet, formed, drilled etc, and I am attempting to draft the control plan.
My question is with regard to the product characteristics produced at the punching stage. The component blank is punched from a sheet of titanium by a machine controlled by an NC programme. When identifying the product characteristics for this punching process, should I be identifying all the individual drawing dimensions for which the blank obviously covers. I have not identified all these individual dimensions on the PFMEA.

thanks

Colin

 

[Manix]

Re: Control plan requirements

Your product characteristics would indeed need to be stated and the dimensions of the blank would be included. As would any visual requirements for the blank. You would probably want to check the the blank is complete and does not have any burred edges and the like, these are all Product Characteristics.

Your PFMEA need not contain individual dimensional requriements. This identifies failures within your process so you may look at failure modes that would lead to incorrect dimensions, I.e. Blanking force too high or too low etc..... This would lead you to control your process sufficiently in the control plan. So other characteristics you could include in your control plan could be the Stamping pressure settings, which would then be followed up with inspection frequencies and control methods in the preceeding columns (assuming you are using the QS / TS style Control Plan form).

Basically your control plan can contain both process and and product characteristics and all need to be inspected and controlled as per your plan.

I hope this helps!

 

[Michael Walmsley]

Re: Control Plan Requirements - Should I identify all the individual drawing dimensio

"Basically your control plan can contain both process and and product characteristics and all need to be inspected and controlled as per your plan."


True,yet
"At a minimum, the info you transfer into your control plan must be those items that have special characteristics in the FMEA."

 

[Jim Wynne]

Re: Control Plan Requirements - Should I identify all the individual drawing dimensio

The only items you need to cover in the control plan are:

• Special characteristics, as Michael suggests;
• Appropriate items from the "Current Process Controls" fields on the PFMEA;
• Anything you want controlled during the operation, whether it be product or process characteristics.

You do not have to list all drawing characteristics; the PFMEA and control plan are risk management tools. If, during the course of the PFMEA process, you identify product or process characteristics that don't need special controls, they don't need to appear on the control plan. In most cases, however, it should be possible to deduce from the PFMEA why you made the decisions you made.

One more note: for every product characteristic on the control plan, there should be an associated process characteristic. It's a process control plan, not an inspection plan.

 

[Manix]

Re: Control Plan Requirements - Should I identify all the individual drawing dimensio

One more note: for every product characteristic on the control plan, there should be an associated process characteristic. It's a process control plan, not an inspection plan.

That's a good point and one that I did not make clear in my initial reply.

Thanks Jim

 

[Raffy]

Re: Control Plan Requirements - Should I identify all the individual drawing dimensio

The only items you need to cover in the control plan are:

• Special characteristics, as Michael suggests;
• Appropriate items from the "Current Process Controls" fields on the PFMEA;
• Anything you want controlled during the operation, whether it be product or process characteristics.

You do not have to list all drawing characteristics; the PFMEA and control plan are risk management tools. If, during the course of the PFMEA process, you identify product or process characteristics that don't need special controls, they don't need to appear on the control plan. In most cases, however, it should be possible to deduce from the PFMEA why you made the decisions you made.

One more note: for every product characteristic on the control plan, there should be an associated process characteristic. It's a process control plan, not an inspection plan.

Hi Jim,
What are special characteristics in the Control Plan? What are these? How am I going to apply these special characteristics in a Speaker Assembly Setup? Please advice.
Thanks in advance.
best regards,
Raffy

 

[Manix]

Re: Control Plan Requirements - Should I identify all the individual drawing dimensio

Hi Jim,
What are special characteristics in the Control Plan? What are these? How am I going to apply these special characteristics in a Speaker Assembly Setup? Please advice.
Thanks in advance.
best regards,
Raffy

Your special characteristics will normally be defined by your customer, if they are design responsible, or yourself if you are design responsible.

In my experience SC's are usually added to characteristics that effect fitment of the loudspeaker to the application (hole centres etc... but are obviously dependant on the fitment requirements), and will almost certainly be performance characteristics, usually SPL (average over 20Hz - 20Khz). There may also be a requirement to verify Impedance as an SC.

Like I say these are usually defined by the customer and require increased inspection regimes and Initial Capability studies.