Machining Ground Flat Stock - Tool Steel

[cmnewcomer]

I'm making small parts out of 1/8" precision ground flat stock by chain drilling and filing. Now that I have a CNC mill, I'd like to try machining these parts using a 3/32" 4 flute carbide end-mill or some other type of end-mill that will hold up to this material.

I would assume that I would need slow spindle speeds, feed rates, and depths of cut along with plenty of coolant but was hoping that those that work with this type of material could give some advise.

Best Regards.

Carl

[HuFlungDung]

In the annealed state, alloy toolsteels can still be a bit tough, but not bad when you are using carbide tooling. Water hardening tool steels are about as easy as mild steel.

Using coolant with carbide can be a gamble in that the heating/cooling stress on the carbide can cause it to fail sooner than simply running it dry (hot). In lighter finishing cuts with small diameter tools, coolant is probably okay, for the simple reason that the tool is probably running well below rated speed and is not generating so much heat.

Small tools have small gullets so probably the primary reason for failure is chip loading. You need an air blast to move the chips quickly out of the tool to avoid recutting and chipping the tool whenever it is fully engaged (widthwise) in the cut.

Use the correct coated carbides for milling steels.

[cmnewcomer]

Thanks for the reply HuFlungDung.

This will be the first time I've machined guage stock on the mill so I'm not sure about the details. I'm using oil hardening guage stock so it may be a little tougher as you eluded to.

Based on my mill which will only go up to 2,800 RPM and some of the Feed/Speed recommendations I've seen for standard carbide in 1/8" diameter, it looks like I could start at 5.6 IPM but that seems too fast. I'll probably start at 2 IPM since I will be slot milling running very shallow depths for each pass.

Thanks again.

Best Regards.

Carl

[PinMan]

The best bet for speeds and feeds is going by the recommendation of the tool's maker. Most all manufacturer's have charts that give SFM ratings for their tools.

Then, figure in the rigidity of the machine and setup. I usually use 50% of the manufacturer's recommendation as a starting point, then dial it up from there.

I use ME Consultant 2.0. It is an exceptional tool where you can input your material, cutter, max spindle speed and many different variables. It is usually dead on with starting points.

Hope this helps you out some