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Distortion on flat plate

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Distortion on flat plate

Postby Homemade » Wed Sep 13, 2017 9:00 am

How do you reduce or eliminate warping and distortion on flat plate when adding hard surfacing?
I work in a gravel pit and often we are changing out abrasion resistant (ar400 and similar rated stuff) because it's wore threw. To extend the life of the plates and to keep costs down on buying such thick stuff, we clad the plates with hard surfacing rods/mig wire in a dot or diagonal box pattern. I'll tack and clamp the crap out of the plate but it sometimes warps really bad and is a pain to get bolted back into place. Any suggestions of how to minimize the warpage?


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Re: Distortion on flat plate

Postby MinnesotaDave » Wed Sep 13, 2017 1:28 pm

Only method I've had work is to pre-stress the plate the opposite direction.

Place something under it, clamp it down so it bends backwards a little, weld it.

When the clamps are released it pulls back straight.

I've only used it on smaller material than you're talking about, but it works good.
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Re: Distortion on flat plate

Postby Poland308 » Wed Sep 13, 2017 7:27 pm

Is there a reason you can't leave it bolted in place when you run the stringers?
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Re: Distortion on flat plate

Postby thatoneguy » Fri Sep 15, 2017 3:34 pm

Either leave it bolted in place, pre-stress, pre-heat, or change your weld pattern to something that spreads the heat out more evenly. For example, instead of welding bead after bead after bead right next to eachother and slightly overlapping until you've covered the whole thing, weld a bead, weld 90* away from that one and keep doing that. Eventually you will have welded a square or rectangle depending on what youre working on. then just keep doing that until it is all filled in. Should help at least a little bit.
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Re: Distortion on flat plate

Postby Homemade » Mon Sep 18, 2017 7:02 am

Poland308 wrote:Is there a reason you can't leave it bolted in place when you run the stringers?


Sometimes that would work but mostly not because it's attached to a piece of equipment in the field and welding is done in the shop.

The previous welder that has since retired used to take forever welding up hard surfacing. He would only run one inch of weld at a time, then let the plate completely cool. Took him weeks sometimes for a simple plate but it was straight as an arrow and fit every time.


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Re: Distortion on flat plate

Postby Homemade » Mon Sep 18, 2017 7:02 am

Poland308 wrote:Is there a reason you can't leave it bolted in place when you run the stringers?


Sometimes that would work but mostly not because it's attached to a piece of equipment in the field and welding is done in the shop.

The previous welder that has since retired used to take forever welding up hard surfacing. He would only run one inch of weld at a time, then let the plate completely cool. Took him weeks sometimes for a simple plate but it was straight as an arrow and fit every time.


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Re: Distortion on flat plate

Postby MinnesotaDave » Mon Sep 18, 2017 7:07 am

Homemade wrote:
Poland308 wrote:Is there a reason you can't leave it bolted in place when you run the stringers?


Sometimes that would work but mostly not because it's attached to a piece of equipment in the field and welding is done in the shop.

The previous welder that has since retired used to take forever welding up hard surfacing. He would only run one inch of weld at a time, then let the plate completely cool. Took him weeks sometimes for a simple plate but it was straight as an arrow and fit every time.


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Weeks? Good lord...talk about milking a job by the hour...lol

Take what you learn about the direction of pull, and how much it pulls - use that to determine the amount of pre-stress you need to put into it when clamping it down with a reverse bow.

The video is cheesy, but gets the point across :)

https://m.youtube.com/watch?v=2vuGlcbDwKY
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Re: Distortion on flat plate

Postby Homemade » Mon Sep 18, 2017 10:27 am

Ill try the pre stressing. Clamping it to the table over some round stock in the same direction as the weld line I think we'll be the best. I've tried just tacking it flat down but, it still bowed.


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Re: Distortion on flat plate

Postby MinnesotaDave » Mon Sep 18, 2017 1:47 pm

Homemade wrote:Ill try the pre stressing. Clamping it to the table over some round stock in the same direction as the weld line I think we'll be the best. I've tried just tacking it flat down but, it still bowed.


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Yep, tacking it flat will do that. The stress is still there and when the clamps get released, the piece still bows.
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Re: Distortion on flat plate

Postby weldin mike 27 » Mon Sep 18, 2017 4:48 pm

I did some presetting recently. the plates were 1.5 meters long by 550mm wide x 10mm thick. I had to weld stiffeners across the length. Granted i was able to put a minimum amount of weld, (small stitches) but the idea is the same. I had a 3/4 nut and a small piece of 5mm plate for the packers (total- 20mm ish) clamped down hard at each end. Take into account the length of your job. The longer the plates, the higher your packers must be.
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