Weld Parameter recording
by Kevin Bohne
(Mackay QLD Australia)
It has been my experiences many times were there is a wide variance of understanding on how to take effective welding parameter measurements. Certainly it is not a precise science however there are methods that need to be considered as more practical than others to give the most realistic expectations for consistent metallurgical and mechanical properties.After all this is why we go through this exercise to maintain an expected outcome that was qualified in the WPQR then allowable ranges applied in the WPS.
I find that the most consistent method is to use meters with built in average value functions so there can be no guessing or additional calculations to reach average average values and the potential for inadvertent mistakes. Even this is not precise method however better than the additional work required when using meters with no average functions available.
Collecting the information for each weld pass in a multi pass procedure depending on the speed the operator is making the joint at can be busy especially considering you need to gather Amps , volts and travel speed quickly and make legible recordings in the WPQR runsheet or monitoring QA docs. I use 2 meters one for volts and 1 for Amps a the same time to achieve these recordings.
This is the first area that needs to be considered for consistent data collection.
The second step when applying the methods to condensing the collected data into a usable WPS that the welder can logically use has also a wide variance of understanding. The key here is to plan the PWPS carefully and ensure the welder at the time is guided to make consistent weld passes that return limited variance for A, V and TS values with in a consistent range were ever possible. This allows the condensing of values into the smallest number of weld grouping brackets ie lines in the WPS. This is commonly 4 lines Root, Hot , fill and cap on an average WPS but may be less. I have seen a lot of WPS documents that also have multiple fill pass grouping lines which means the welding initially in the PQR data collection stage was not controlled properly. No welder will want to use this WPS especially if being monitored by a third party inspector and no Welding supervisor would want this pressure if they understand the complexity.
I find using this approach gives the best results to get MAX MAX MIN and MIN MIN MAX ranges easily that fall within the essential variable ranges in the standards.
The key parameter to control at the WPQR stage is travel speed because the welders eyes are not calibrated to control this and this is were we find the biggest problem.
The whole process is not precise and requires a diligent and consistent effort on the part of a properly trained and experienced welding supervisor or welding coordinator.
Welding is designated as a "Special Process", That,s why we refer to it as a "black art" for those who have limited knowledge and experience
As for the performance review systems you spoke about, I agree with your sentiments however I have found some to be a lot better and fairer than others when it comes to the personal reaction being told you are average or below average.This does not remove the reaction we all have experienced at one time or another.