Laser Welding PFMEA (Process FMEA) - Metal
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Ron Rompen
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The company I am working for is one of the primary users of laser welding, and list it as their core competency.
Due to the non-disclosure agreements that I signed, I can't share the PFMEA with you, but I can give you a couple of guidelines that hopefully will be of help.
Contamination of the welded parts, particularly by oil, can be a huge problem. This can cause 'blooming' of the focal point, resulting in a weak weld, or in the case of oil, act as an additional focal point, resulting in excessive heat, distortion and burnthrough.
Flatness of the two parts in relation to each other is critical, as there is no filler metal being used. We control our parts to < 0.20mm flatness over the entire mating surfaces.
Traceability of laser-welded components is (usually) a major requirement, as these are commonly safety-critical components. Be sure your PFMEA addresses the traceability issue thoroughly.
Control of the welding process itself is an ongoing development; two similar parts will not always react in the same way.
Evaluation of the welded bond should (by agreement with the customer) be controlled by pull test, rather than by sectioning. (Pull testing is much faster to perform, although the initial equipment cost is somewhat higher).
During the program analysis stage, pay attention to what is to be welded, and the length of the weld. A non-critical surface may not require as much weld as was initially shown in the print (design engineers are as subject to error as the rest of us).
Hope this is of some help. Feel free to contact me directly if there are any other questions that I can answer.
Due to the non-disclosure agreements that I signed, I can't share the PFMEA with you, but I can give you a couple of guidelines that hopefully will be of help.
Contamination of the welded parts, particularly by oil, can be a huge problem. This can cause 'blooming' of the focal point, resulting in a weak weld, or in the case of oil, act as an additional focal point, resulting in excessive heat, distortion and burnthrough.
Flatness of the two parts in relation to each other is critical, as there is no filler metal being used. We control our parts to < 0.20mm flatness over the entire mating surfaces.
Traceability of laser-welded components is (usually) a major requirement, as these are commonly safety-critical components. Be sure your PFMEA addresses the traceability issue thoroughly.
Control of the welding process itself is an ongoing development; two similar parts will not always react in the same way.
Evaluation of the welded bond should (by agreement with the customer) be controlled by pull test, rather than by sectioning. (Pull testing is much faster to perform, although the initial equipment cost is somewhat higher).
During the program analysis stage, pay attention to what is to be welded, and the length of the weld. A non-critical surface may not require as much weld as was initially shown in the print (design engineers are as subject to error as the rest of us).
Hope this is of some help. Feel free to contact me directly if there are any other questions that I can answer.
Thanks Ron,
I saved your post into word format and as an attachment to facilitate those who search our 'post attachments list'.
D
DrM2u
I do not have a PFMEA readily available right now but I did work with Laser Welding in the past. Here are some other considerations in addition to the material contamination and condition (flatness) posted by Ron:
- process parameters: speed (too fast skips, too slow burns), power (too much burns, not enough won't weld), focal distance (affects weld depth/penetration)
- equipment maintenance: lens & mirror regular cleaning & replacement (poor condition affect focal length, beam width & transmission of power), laser element maintenance (ensure consistent power)
- weld fixture maintenance: minimize variation in component location & pressure
- assist gas flow (if applicable): reduce potential for burns (eliminate oxigen) and contamination (blow off particulates & eliminate corrosive reactions)
- weld strength inspection: pull test, as mentioned by Ron
- weld penetration: section & etching
A process validation is strongly recommended as the quality of the product can be verified only through destructive testing.
- process parameters: speed (too fast skips, too slow burns), power (too much burns, not enough won't weld), focal distance (affects weld depth/penetration)
- equipment maintenance: lens & mirror regular cleaning & replacement (poor condition affect focal length, beam width & transmission of power), laser element maintenance (ensure consistent power)
- weld fixture maintenance: minimize variation in component location & pressure
- assist gas flow (if applicable): reduce potential for burns (eliminate oxigen) and contamination (blow off particulates & eliminate corrosive reactions)
- weld strength inspection: pull test, as mentioned by Ron
- weld penetration: section & etching
A process validation is strongly recommended as the quality of the product can be verified only through destructive testing.
Ron Rompen
Trusted Information Resource
Another factor to consider is the availability of the laser supplier for on-site support. Laser welding for us has been an ongoing development process, and our laser supplier and our system integrator have working extensively with us to improve their product/supply.
V
valenta.tomas.81
Dear forum colleagues. Hereby I would kindly like to ask you for your help. Iam working for company which is several years in the business and its core procesess are welding,stamping,painting. Despite this fact our PFMEAs has never been detailed but only general regarding welding defects. Having a new customer from VW group we have to create generic - detail PFMEA for MIG, RP and LASER welding.
I would appreciate from you professionals to help me with this task and maybe share with me some hints,advises etc. Iam not asking for your PFMEAs and my aim is not to copy paste but learn from the others and improve our PFMEA approach as quick is possible.
Thank you in advance for your support
Tomas
I would appreciate from you professionals to help me with this task and maybe share with me some hints,advises etc. Iam not asking for your PFMEAs and my aim is not to copy paste but learn from the others and improve our PFMEA approach as quick is possible.
Thank you in advance for your support
Tomas
C
cosmobenz
hello, did you ever receive a laser welding template? I really need one my self.
Geez, it seems as if no one is willing to give one out. Thanks,
Geez, it seems as if no one is willing to give one out. Thanks,
The attached paper is from this link:
https://www.e-ijaet.org/media/0001/79I8-IJAET0805884-PROCESS-FAILURE-MOD.pdf
I think it would give a good start for a laser welding PFMEA. I know that it is for TIG welding, but like I said, it can give a start.
The Word Document is a compilation of the first Word document Harry generated from Ron's post, and I added some of the information from DrM2U's post.
Hope these help.
https://www.e-ijaet.org/media/0001/79I8-IJAET0805884-PROCESS-FAILURE-MOD.pdf
I think it would give a good start for a laser welding PFMEA. I know that it is for TIG welding, but like I said, it can give a start.
The Word Document is a compilation of the first Word document Harry generated from Ron's post, and I added some of the information from DrM2U's post.
Hope these help.
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