DFMEA, PFMEA and KCC's (Key Control Characteristics) Relationships (2024)

Hello,

Thanks for reading this post.

We have created a DFMEA for one of our product lines. Right now, we are working on a PFMEA and Control plan for the same line based on the failure modes identified in the DFMEA.

I was looking for some clarification about the KCC's. From my understanding, the DFMEA brings to light the critical characteristics that we juxtapose with the PFMEA and identify the process steps where the characteristics appear. Based on the criticality and control requirement at those steps, we seperate the KCC's from the other characteristics . Am I correct? What is the relationship between the DFMEA, PFMEA and KCCs?

Thanks again for your help...

Aj

Re: DFMEA, PFMEA and KCC's

For the benefit of our Fellow Covers, what does KCC mean?

Stijloor.

Re: DFMEA, PFMEA and KCC's

Key Control Characteristic.

Re: DFMEA, PFMEA and KCC's

Please use these two documents fore your use:
The old standards never fail.

Re: DFMEA, PFMEA and KCC's

Ajgupta said:

I was looking for some clarification about the KCC's. From my understanding, the DFMEA brings to light the critical characteristics that we juxtapose with the PFMEA and identify the process steps where the characteristics appear. Based on the criticality and control requirement at those steps, we seperate the KCC's from the other characteristics . Am I correct? What is the relationship between the DFMEA, PFMEA and KCCs?

Click to expand...

You are correct that the DFMEA is completed first. The DFMEA is used to identify potential Key Product Characteristics (KPC). KPCs may also be identified through DFSS tools. These are the Critical to Quality (CTQ).

Next the PFMEA is completed making sure that all potential KPCs are included in the review. During the PFMEA, the potential KPCs are confirmed as true KPCs or ruled out. If the KPCs are confirmed, the process is reviewed to identify potential Key Control Characteristics (KCC).

If you are familiar with the Six Sigma view of processes in terms of y = f(x) [Output = a function of input variables], then KPC = f(KCC). KCCs are those process parameters that have a significant effect on a KPC. In a heat treat operation, time and temperature in the oven, and quench media and temperature would be KCCs to a KPC of hardness.

Re: DFMEA, PFMEA and KCC's

Miner said:

You are correct that the DFMEA is completed first. The DFMEA is used to identify potential Key Control Characteristics (KCC). KCCs may also be identified through DFSS tools. These are the Critical to Quality (CTQ).

Next the PFMEA is completed making sure that all potential KCCs are included in the review. During the PFMEA, the potential KCCs are confirmed as true KCCs or ruled out. If the KCCs are confirmed, the process is reviewed to identify potential Key Process Controls (KPC).

If you are familiar with the Six Sigma view of processes in terms of y = f(x) [Output = a function of input variables], then KCC = f(KPC). KPCs are those process parameters that have a significant effect on a KCC. In a heat treat operation, time and temperature in the oven, and quench media and temperature would be KPCs to a KCC of hardness.

Click to expand...

In terms of general usage, you have the two things backwards. "KPC" is generally interpreted as Key Product Characteristic, which is a feature of the product which requires special process controls, which are Key Control Characteristics. For each KPC there should be one or more KCCs, but there could be KCCs without any KPCs.

Re: DFMEA, PFMEA and KCC's

Jim Wynne said:

In terms of general usage, you have the two things backwards. "KPC" is generally interpreted as Key Product Characteristic, which is a feature of the product which requires special process controls, which are Key Control Characteristics. For each KPC there should be one or more KCCs, but there could be KCCs without any KPCs.

Click to expand...

You are correct. I haven't worked with GM for a few years. Swap the two and the rest of the post is still accurate.

Re: DFMEA, PFMEA and KCC's

Miner said:

You are correct that the DFMEA is completed first. The DFMEA is used to identify potential Key Control Characteristics (KCC). KCCs may also be identified through DFSS tools. These are the Critical to Quality (CTQ).

Next the PFMEA is completed making sure that all potential KCCs are included in the review. During the PFMEA, the potential KCCs are confirmed as true KCCs or ruled out. If the KCCs are confirmed, the process is reviewed to identify potential Key Process Controls (KPC).

Click to expand...

Thanks. I wanted to confirm my understanding of the process was not flawed.

If we have a 100% inspection (In-process as well as actual inspections), does that necessarily have to imply that the characteristic is a KCC? Say if the machinist visually or with a gage inspects the bore diameter as he knows that the tool is prone to moving away from Caliberation. What would such a situation be?

Any rule-of-thumb's that you may know about KCC's?

appreciate the responses.

Re: DFMEA, PFMEA and KCC's

Ajgupta said:

Thanks. I wanted to confirm my understanding of the process was not flawed.

If we have a 100% inspection (In-process as well as actual inspections), does that necessarily have to imply that the characteristic is a KCC? Say if the machinist visually or with a gage inspects the bore diameter as he knows that the tool is prone to moving away from Caliberation. What would such a situation be?

Any rule-of-thumb's that you may know about KCC's?

appreciate the responses.

Click to expand...

See my earlier post in this thread wrt KCC/KPC. If the part is being inspected, it's a product characteristic. If the machine (or other process feature) is monitored and adjusted as necessary, it's a control characteristic. KCCs govern KPCs.

In answer to your question, if there are no customer-defined KPCs (customers normally won't specify KCCs), you're free to call it whatever you want to call it. If it's something that needs special controls, those controls should be identified and invoked, regardless of what you call them.

Typical Automotive Trilogy Development

Re: DFMEA, PFMEA and KCC's

Has anyone every heard of an organization having the defined procedure (as in a work instruction) to establish KCCs?