Electronics > Mechanical & Automation Engineering

Remove warp from aluminium plate?

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aneevuser:

--- Quote from: jpanhalt on May 24, 2022, 09:59:38 am ---I think "the long cut" may apply to the sheared edge in your top photo.  Although, the curl looks to be in both directions.  One sees curl like that when relatively narrow strips are sheared from larger plates.  Are you sure there was no curl before drilling?  Was it fully supported while drilling?

--- End quote ---
No, it was fine before drilling, and it was indeed supported fully. So it was my drilling that caused the problem, but I can't tell you why.

andy3055:
Deforming happens in this kind of work due to heat. Possible causes can be blunt bits and too much force. If you pour water or coolent used for this sort of work, it should stay flat. That is in addition to clamping sufficiently. Also keep the clamping on till it cools down.

aneevuser:

--- Quote from: andy3055 on May 24, 2022, 05:02:35 pm ---Deforming happens in this kind of work due to heat. Possible causes can be blunt bits and too much force.

--- End quote ---
That's a useful observation. I suspect that if heat is the problem, then it was due to the countersinking - I countersunk an M8 hole without coolant, and I have a feeling that I noticed the warp after I'd done that.


--- Quote ---If you pour water or coolent used for this sort of work, it should stay flat. That is in addition to clamping sufficiently. Also keep the clamping on till it cools down.

--- End quote ---
Yes, I tend to be a bit lax with coolant - need to pay more attention in future. I rarely drill plate though, and heat doesn't seem to be much of a problem with box section.

ndzied1:
Stresses in sheet and plate is very common due to the "memory" effect mentioned in this article. A plate that looks flat often warps after some machining operation (like drilling) that releases some of the stress in one place that was balancing out the plate. Now with unbalanced stresses, it warps. So it's probably more correct to say that the drilling released memory stresses in the plate rather than the drilling being a direct cause of the warpage.

https://www.ryerson.com/resource/the-gauge/temper-pass-vs-stretcher-level

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