machining stainless

[MachineTom]

A two flute is not for SS, use a 3-4 flute, rpm should be 1500 with HSS and 3K + for carbide. What speeds were you using? I remember the first time using carbide drills at 5K rpm, I was thinking it was nuts to do so, but man does it work.

 

[Mosey]

600 rpm! Embarrassing isn't it.

 

[MachineTom]

Not at all. But if you do it again,

 

[Mosey]

MachineTom
Here's the strategy going forward.
5/32" 4 spiral-flute HSS mill. Lot's of brushed-on cutting fluid at the cutter tip.
Grind off the burnt end of the mill, as I don't need to center cut.
1500 rpm
Feed gently into the work, burying the tip into the aluminum pallet about 1/16"
Work is bonded to aluminum pallet with hot-melt glue.
Sound OK?
Wish me luck.

 

[Swede]

Mosey, I am concerned about

Grind off the burnt end of the mill, as I don't need to center cut.

The ends of the cutter are for more than center cutting. If you are contacting ONLY on the flank of the cutter, then you can grind the end off all day long, but if you are expecting to machine a surface, it doesn't sound good to me.

Look at the chips when you cut. They will probably come off tan to blue. If chips are too small, then the steel is work hardening, and the cutting edges will be ruined in short order.

I personally like carbide when using small cutters on stainless. Although they are brittle, they retain sharpness so much better than HSS, and each tooth is more likely to bite and cut rather than rub. Once HSS begins to rub, it'll simultaneously work harden the material, AND dull the cutter fatally.

Good luck!

 

[MachineTom]

Mosey, That will create another issue, an end mill with a flat bottom, will not work if the bottom rubs on the material being cut. If you are only milling with the flank no problem, but if you were cutting 1/4 material 1/8 deep, not good, if you are cutting 1/4 material and 1/4 deep so the end of the mill cuts air its fine. And under those conditions you can leave the end burnt anyway, since it does nothing.