aluminium plate - 1800mm x 950mm x 1.5mmprocesses - i) sandblasting ii) polyethylene coating iii) matt blastingWhy does aluminium plate warp after the first process?How to prevent warping? Other than increasing material thickness (weight issue)
Cold rolled aluminium may get stress relieved by sand-blasting and thus get warped. Normally warping should not take place if sand blasting is done on both sides. Another potential reason could be lack of adequate support for the plate during blasting. Check out these factors and take corrective action.
I don't know about aluminium or metallurgy but I have direct experience of grinding and lapping silicon wafers for the integrated circuit industry. I know that these grinding-type processes (and I think sand blasting may be similar) will introduce stress on the machined side of a thin silicon plate. The damage affects the atomic scale silicon lattice (aluminium will be similar only it may be polycrystalline as opposed to the single-crystal lattice with which I am familiar). This stress acting on one side of the plate causes the plate to bend or warp. For the theory behind plate bending due to stress try googling Stoney's equation. Note that this stress and usually the warpage might be removed by performing the same operation on the opposite side of the plate (the stresses induced then cancel each other). For silicon we can also reduce or remove the stress by polishing away the machined surface.
It warps because the blasting is relieving stresses in the material. If you stress relieve the material first, it's a heat treating process, then flatten it with a press brake and it will stay flat during sand blast. You might try using aluminum tooling plate, and a chemical etch if your coating needs it to adhere.
If you can, try and get ceramic plates, they are sooooooo much better than titanium or aluminum because they don't cause as much damage to your hair. But, if you have to choose between titanium or aluminum, go with titanium. The only thing aluminum will do for your hair is fry it and give it split ends. Please don't waste your money on a straightener with alumium plates, :)
