Metallurgy Query - Welding cutting blades

Ray13

Hi, I am not sure if this would be the right forum but if any engineers or metallurgists (or anyone in the know) could point me in the right direction I would appreciate it.

The query is this, on a grass cutting mower, would excessive welding of the cutting blades (21 blades approx) weaken the structural integrity of the unit? can pm the photos for an opinion...

Turbulent Bill

It's possible, but I don't know how likely it is. Welding can create brittle heat affected zones, and combined with the vibration loading from the mower it could lead to fatigue failure.

Photos of an intact unit won't tell a lot ;you'd need to get an analysis of the metal composition and any existing cracks. If it's already broken, the appearance of the broken surface can suggest whether it's fatigue or not.

Ray13

Photos show excessive badly welded components, distorted blades etc

mawk

If you cannot get a new blade for it, I would recommend grinding the welds flat which would show up a lot of faults. Tig weld in any voids then temper to remove internal stress before hardening back to a cutting edge.

Or.. And this is only if it's not a safety issue, try using the mower. Maybe they are stronger welds than they look. I'm not familiar with the mower and don't know how the blades are housed

Ray13

mawk wrote: »

If you cannot get a new blade for it, I would recommend grinding the welds flat which would show up a lot of faults. Tig weld in any voids then temper to remove internal stress before hardening back to a cutting edge.

Or.. And this is only if it's not a safety issue, try using the mower. Maybe they are stronger welds than they look. I'm not familiar with the mower and don't know how the blades are housed

Thanks, what's ur expertise in the area? Sounds good

Ray13

Ray13 wrote: »

Thanks, what's ur expertise in the area? Sounds good

Is welding blades bad practice?

Turbulent Bill

Another issue might be that the distortions and welds are unbalancing the blades, leading to premature failure of bearings etc. Without knowing what happened it's just guesswork.

mawk

Ray13 wrote: »

Is welding blades bad practice?

It's very common in fixing band saw blades. Lawnmowers.. No idea.