Benchmarking of Capability, Accuracy and Stability analyses - In Heat treatment

[Seyed]

Hey,

Last year our company that is a research institution performed capability analyses at two different heat treatment factories for studying the reproducibility during heat treatment. However, we only focused on the main furnace (case carburizing) and exclude the pre and post processes, which was due to lack of time and money.

However, we find that when it comes to i.e. carbon content and case depth we obtained rather good values and could see how the furnace behaved. But in case of surface hardness and core hardness we failed, which lead to do MSA for the hardness equipments. We did see that the spread from the equipment is too large, in some cases larger that the tolerances. How can one rely on a equipment that in some cases shows a larger spread than the tolerances that you have on your products?

We also performed a TUS-analysis (Temperature Uniformity Survey) that is recommended in CQI-9 for heat treaters.

Now we are interested to continue our work by investigate how other use the available tools such SPS, MSA, CQI-9, PPAP and etc for performing capability analyses in their facilities. Our primary focus is of course heat treaters but other how use the tools effectively are also of interest.

Please let us discuss and learn from each other. We are willing to set up meetings (telephone) for further discussions in the field.





Seyed

 

[Stijloor]

Hey,

Last year our company that is a research institution performed capability analyses at two different heat treatment factories for studying the reproducibility during heat treatment. However, we only focused on the main furnace (case carburizing) and exclude the pre and post processes, which was due to lack of time and money.

However, we find that when it comes to i.e. carbon content and case depth we obtained rather good values and could see how the furnace behaved. But in case of surface hardness and core hardness we failed, which lead to do MSA for the hardness equipments. We did see that the spread from the equipment is too large, in some cases larger that the tolerances. How can one rely on a equipment that in some cases shows a larger spread than the tolerances that you have on your products?

We also performed a TUS-analysis (Temperature Uniformity Survey) that is recommended in CQI-9 for heat treaters.

Now we are interested to continue our work by investigate how other use the available tools such SPS, MSA, CQI-9, PPAP and etc for performing capability analyses in their facilities. Our primary focus is of course heat treaters but other how use the tools effectively are also of interest.

Please let us discuss and learn from each other. We are willing to set up meetings (telephone) for further discussions in the field.





Seyed

Any responses?

Thank you very much.

Stijloor.

 

[bobdoering]

But in case of surface hardness and core hardness we failed, which lead to do MSA for the hardness equipment. We did see that the spread from the equipment is too large, in some cases larger that the tolerances. How can one rely on a equipment that in some cases shows a larger spread than the tolerances that you have on your products?

Heat treating is an extremely difficult subject. Everyone wants to control it, but the variables going into it are nearly impossible to control (material chemistry - lot to lot, rack loading consistency, etc.) To look at the big picture, you may want to put together a total variation equation - and it will likely be the condensation of a fishbone analysis of the process.

Your MSA analysis is a very good observation. If they are using state-of-the-art analytical equipment (such as micro-hardness with computer area evaluation), then it may be the best technology available for analyzing the case depth. If this is true, then the case depth specification is too tight for the current technology to detect it, and therefore it would be unreasonable to expect you could hold the depth specification that tight. That's right, it may be the spec that has to change...until such time the technology catches up.

Consider this, usually the case depth is performed on a cross section. That is a very small sample of the entire distribution - even on one part - imagine trying to use such a small sample to represent the entire lot. You do that, though, because it is destructive. But, the point is that the error really is far greater than your study, just due to sampling error. Even more reason to consider detecting meeting a tight tolerance an unreachable goal.

 

[Seyed]

Hej,

I agree with you, that heat treatment is a very complex process to control and to measure its outcome, as the variation (uncertainty) with the available equipment are high.

And another funny thing is the requirements that are coming with CQI-9 and other guide lines for heat treaters. In some cases they are impossible to fulfill.

However, I need to come in to contact with others who works with these questions on a dailay bases. I think it is important to start discuss and share how others are working in the field and try to learn from each other.

Please if any one know a company or person or any research institution that are working in the field let me know.

Thanks in advanced.
Seyed