[basilemorani12]

I want to produce a jig for CNC machining, how do you go around choosing between them? It's an industrial part expected to be in contact with water-based coolant while machining.

[joeavaerage]

Hi,
what wrong with ordinary mild steel?

My machine is homemade out of steel and cast iron, not in anyway painted or rust treated and yet after four years there is virtually no rust at all, and I use water based coolant all the time. The
whole point of water soluble oils is that they have rust inhibitors in them, and my experience is they work. Why bother using an expensive material like stainless when mild steel would do?.

Craig

[peteeng]

Hi Basil - 304L is low carbon and the main reason to use it is if its being welded. 304SS will rust in certain conditions because it has a relatively high carbon content plus it changes for the poorer during welding (to keep the story simple). The low carbon version L changes much less. So 1) the L is mainly to do with welding practice 2) if its not being welded then their is not much difference 3) if its a machining fixture there's not much value in using SS. Its harder to machine etc etc. Unless you are trying to stop contact contamination to something? If the part being made is steel then mild steel is the go... Peter

[metalmayhem]

all you probably need is a steel like a36 which is far more cost effective . If the parts are aluminum then I'd alternatively go with aluminum , hard anodized it lasts for years