[cce1911]

I've got a project involving pistol targets made from AR500 steel. I'm under the impression that cutting the shapes with CNC waterjet is a better option than cutting with plasma because of a minimal heat affected zone. I've been told that plasma, while not as bad as oxy/acetylene, will still temper the edge of the plate leading to cracking. Can anyone comment on the pros and cons of cutting 3/8" AR500 with waterjet vs plasma?

Also, I need som .375" dia holes in the plates. Can they be cut with wj or plasma or will they need to be drilled? Tolerances are not extremely critical on these parts.

[jimcolt]

There are air plasma systems that can cut AR plate with excellent speed and quality, generally on AR plate the edge is affected by heat from the process and actually softens (the opposite effect occurs on A36 plate, a case hardening occurs) the edge in about .006" to .010". If you are comparing to waterjet....then don't compare air plasma cuts, rather, you should be comparing an industrial high definition plasma cut. Hydefinition plasma systems will use oxygen as the plasma gas and will have a very slight softening effect on the edge. If it is a Hypertherm high definition system equipped with True Hole technology, the holes will be "bolt ready" (virtually no taper) and will be cut with oxygen/oxygen.....with very little effect to the edge hardness.

Plasma will cut 3/8" AR plate at speeds that are 5 to 10 times faster than an abrasive water jet (depending on the water jet pressure). Plasma systems will cut parts at a much lower price as compared to a water jet, and will hold tolerances in the plus or minus .010" range (high definition) or in the plus or minus .025" range (air plasma on a low cost cnc). Abrasive water jet will make no hardness changes to the edge quality, and can hold tolerances in the .003" to .006" range, depending on the cnc machine and the water jet design.

Sorry for the quality of the pics: the first two are gauge pins inserted through 1/2" diameter holes cut in 1/2" steel, the first using tru hole, the second using a high definition plasma without true hole. The last picture is showing holes cut with a TrueHole equipped plasma on steel, no taper. The True Hole process is only available on Hypertherm HPRXD plasma systems that are used on TrueHole enabled cnc machines.

Jim Colt Hypertherm (we produce plasma's, abrasive water jets, fiber lasers)

I've got a project involving pistol targets made from AR500 steel. I'm under the impression that cutting the shapes with CNC waterjet is a better option than cutting with plasma because of a minimal heat affected zone. I've been told that plasma, while not as bad as oxy/acetylene, will still temper the edge of the plate leading to cracking. Can anyone comment on the pros and cons of cutting 3/8" AR500 with waterjet vs plasma?

Also, I need som .375" dia holes in the plates. Can they be cut with wj or plasma or will they need to be drilled? Tolerances are not extremely critical on these parts.

[cce1911]

Thanks Jim, this was a great response!

[JUKKA V]

If You need good quality it can be cut very well with laser. If plasmas quality is adequate it is obviously cheaper.
BUT with laser your heat affected zone for 10 mm plate is about 00,1-0,2 mm and effect in hardness are a lot smaller than with plasma or flame.

Of course with water jet you have zero haz.

[danaman]

I cut ar500 steel pretty rapidly with my chinese 2.2kw cnc router. The 5/8" endmill works well for me.