Sandblasting sheet metal

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I've read on multiple posts that you shouldn't sandblast sheet metal for fear of warping. Just trying to learn, what causes the sheet metal to warp? What is the minimum thickness the sheet metal should be in order to safely sandblast? If sandblasting is the only option, are there any useful instructions a person should follow to prevent or minimize the risk of warping?

 

[MikeandKeri]

Heat is generated by the sand impacting with the surface. The thinner the material, the faster it heats and warps. If you move rapidly, the heat has less chance to raise to the temperature thereby reducing the amount of warping. Some alternative media, such as crushed walnut generate less heat.

 

[JD Dave]

Most sheet metal can be safely sandblasted. The thinner it is, the more risk of warping. Angle the sandblasting at about 45-60 degrees, never straight on.

 

[showcrop]

I think that this is more of an urban myth than a real problem. Sure with a high powered system running at 120 PSI you could easily do damage but even if you had that you would of course run it at a much lower pressure for thin metal. I have blasted plenty of sheet steel with never a hint of a problem.

 

[Mike(NEOhio)]

I've done it with my home-built setup. Not so much heat as it is the peening action. Just keep the nozzle back a few inches and don't dwell on one spot very long.

 

[jwal10]

There are other media and coarseness of sand, depending on what you are trying to do. I have used beads, walnut shells, coal and soda, some for light work with less heat....James

 

[BarnyardEngineering]

I think that this is more of an urban myth than a real problem. Sure with a high powered system running at 120 PSI you could easily do damage but even if you had that you would of course run it at a much lower pressure for thin metal. I have blasted plenty of sheet steel with never a hint of a problem.

That's assuming the person knows what they're doing. Most people just buy a cheap sandblaster, dump a bag of play sand in, hook it to their air compressor, and go to town.

 

[showcrop]

That's assuming the person knows what they're doing. Most people just buy a cheap sandblaster, dump a bag of play sand in, hook it to their air compressor, and go to town.

And unless they happen to have a huge diesel powered air compressor in their garage they spend an hour to do a square foot with no chance of damaging their steel.

 

[Hemmjo]

I've read on multiple posts that you shouldn't sandblast sheet metal for fear of warping. Just trying to learn, what causes the sheet metal to warp? What is the minimum thickness the sheet metal should be in order to safely sandblast? If sandblasting is the only option, are there any useful instructions a person should follow to prevent or minimize the risk of warping?

It totally depends on the the material aluminum, steel, copper brass, glass, plastic, etc. The hardness or temper of the material is a factor. The thickness of the material is a factor, The type blast media factors into the equation. In addition, the air pressure and distance from the nozzle to the work is a factor. Water from a pressure washer can deform and chew a hole in many materials. Back the nozzle away and that problem goes away.

Technically it is not really the heat that causes the deformation. The deformation is caused by the thousands of strikes from the blast media . Just like "peening" a sheet, or deforming a rivet with a ball peen hammer deforms the surface. The deformation creates the heat. Take a piece of steel, bend it back and forth until it breaks, feel the HEAT at the spot you were bending it.

In short, media blasting can be a very effective process, OR, it can damage your parts. It is best test before you blast something valuable.

Anyone who says NO, blasting cannot deform things has not blasted enough different materials.

 

[flying belgian]

I bought old tin ceiling out of a bank to put up in our living room. Took them to a truck body shop for sandblast. They clamped each to a sheet of plywood. Came out perfect.

 

[Sixty7camaro]

I use a cheap, Harbor Freight, cabinet blaster for all the small stuff. The big stuff, wheels, fenders, hood, sides, I took to the local stone mason and he was careful not to build up heat. My panels all turned out great, no warpage.