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Up Topic Welding Industry / Technical Discussions / Plasma vs Laser cut weld edges
- - By gsi (**) Date 09-27-2005 14:53
Typically in our shop all edges that are thermal cut and are to be welded have to be ground to remove any oxidation before welding. Does the same apply for laser cut edges?
Parent - - By gsi (**) Date 09-29-2005 15:10
Is this a dead issue!
Parent - - By CHGuilford (****) Date 09-29-2005 16:28
It may not be a dead issue but it could be a subjective one.
Thsi topic has been discussed in previous posts, a little searching should locte it for you.

We plasma cut most plates up to 1" thick and oxy-fuel cut anything over that.
We have found that we sometimes get porosity in FCAW welds if we don't remove the oxide layers by grinding. It does not happen in every case but often enough to warrant some grinding attention. Oxy cut edges have not been as much of a problem. Water-jet cutting also has given no problems with welding (not that I would think there would be).
I do not know about laser cut edges.

D1.1 allows mill scale, rust, even some paint, as long as those are not excessive and will not interfere with welding or produce objectionable fumes. You will have to check other codes for their provisions but I believe they are nearly the same.
Based on this, I would say that the oxides left behind would not need removal IF not excessive and there are no welding problems.
Chet Guilford
Parent - - By gsi (**) Date 09-29-2005 19:03
Chet,
Your reply is much appreciated.
Our practice is, any edges that get welded, that have been cut with plasma would be ground or sanded. Recently we have been sourcing a lot of the cutting out to a local laser cutter and the quality is outstanding however we never gave it much thought about grinding edges that need welded. I did recently decide that the laser cut edges would be ground or sanding before any weld.
Respectfully,
Dave


Parent - - By - Date 09-29-2005 19:08
Dave,
You probably made the right decision since cleanliness is of the utmost importance in the welding process, whether it is laser cut or plasma cut. Good decision..
Parent - By backpurge (*) Date 09-30-2005 14:57
A lot depends upon what process gas the laser shop is using and what you have specified.
Oxygen allows for faster cutting but leaves an oxide deposit on the cut edges.
Nitrogen assisted cutting is slower but the edges have no oxides that require removal prior to further processing. It's up to you to do the maths, pay more for cutting and don't do any grinding or vice versa

Cheers - Bob
Up Topic Welding Industry / Technical Discussions / Plasma vs Laser cut weld edges

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