best cutter for engraving 316ss

[swinds]

hi

i have a cnc rounter and want to engrave 316 stainless steel - i have a spindle motor that runs upto 25000 rpm so assume thats fast enough

the letters i need to engrave are approx 4mm high and only about .25mm deep

what is the best tool for the job???

many thanks for any help anyone can give me

karl

[Tweakie]

Hi Buddy,

Nothing like starting out with the tough jobs first.

Stainless is funny stuff (high carbon content and all that), it is relatively soft until it is work or heat hardened then it becomes one of the hardest material you can cut. (If you accidentally overheat a part and the cutter breaks then throw the part away or you will break another cutter).

The professionals may make engraving SS look easy but remember - they have the experience.

Basically you will need a carbide engraving cutter preferably with positive rake, plenty of machine coolant (neither the work or cutter must get hot) and low friction cutting which for me is low spindle rpm and fairly fast feedrate but shallow multi-pass cutting.
I have been buying some of the Chinese cutters lately and they are brilliant for laminates but useless for stainless so you do really need high quality cutters for SS and these are quite expensive.

If you could accept a lower quality of engraving then it may be worth considering dot-impact or diamond-drag these methods are really easy and work every time for me.

Tweakie.

[Phife]

I engrave 316SS plates all the time on my diy cnc.

Its important to note that you are only going to be engraving to about 0.005-0.01 deep, I always do multiple passes of around 0.003 max.

I use the cheap chinese ebay carbide 90degree V bits. There are many sellers and you can get packs of 5-10. I like the 0.02 tip width bits

I run my router full speed (23000rpm) and the feedrates at about 20ipm. Keep your Z slow too around 5ipm (make sure you set your retract clearance to the minimum you can so your Z isnt taking forever to move, I use a 0.03 retract clearance) Also make sure you ramp into your cut.

The most important and hardest thing to achieve is to make sure your machine, table and work piece are perfectly flat. I use a custom vacuum jig to hold the work piece flat.. my machine tends to move a lot, and after a couple of weeks its already so far out that it wont engrave properly. Im building a better machine now to deal with that.

And, lastly, the coolant, its super important you keep the cutter completely submerged in coolant. I use a small foot and a drip system to keep the coolant contained around the cutter. This uses very little coolant but still achieves the effect of keeping the cutter submerged.

Engraving stainless is a real pain, it will take time for you to figure out what works best.. Its a slow process so dont do too quick.