Hard milling tips

[Dave ri]

Hi ,


I am new here and look forward to all the valuable information everyone has here , as well as helping out where i can but i am new to cnc milling we are running a Mikron VCP 600 and would like to hard mill dies , are there any tricks that anyone can shre with me as far as using mist as opposed to flooding the cutter with Crystal cut fluid ? What would be better than PCD cutters for hard milling also ? We are milling a part that is about 3/4 dia. and about .050 deep with no detail . Cutters we will be using will not go smaller than .062 dia. all ball end mills . Thanks for your time !!!



Dave

[epmtool]

Welcome to the forum
What kind of steel at what hardness?
PCD is mainly used on abrasive silicon-aluminum alloys and cannot be used on ferrous materials.
You will most likely want to use good coated carbide endmills with mist or compressed air.
Also spindle speed,tool run out, and tool holder balance will be important limiting factors.
Your best bet would be contacting your tool supplier for feeds/speeds and advice.

[scadvice]

we know the material hardness (RC). That will be a big help in telling you how to go about milling it. Also, depth and size of pocket, cutter sizes you plan on using. Example, P50 tool steel is a piece of cake compared to RC 60 tool steel. Both can be cut, but the approach is very different.

What I can tell you about hard milling without that info is this:

No coolant just reasonably high air flow at the cut point to blow the chips away before they are pulled back in the cut and re-cut again. It helps to keep the tool from chipping and wearing to fast. Coolant will cause the tools edge to crack and chip because the cutting edge gets so hot.

Pre-drill start holes with a spade type profile carbide stub drill.

Use carbide Talin coated stub (only stub) endmills with radiuses on the corners. Hold them as far up into the holder as possible.

Everything emptool said. Eccept...I disagree with him on using misting.
( We have disagree on something!)
Steve

[Dave ri]

Thanks alot guys ! To answer your questions , the material is s-7 die steel RC 55-58 , cavity is about .0505 deep and it shaped like a dish . Great tip about the mist will give it a try . Thanks again for all you input



Dave M

[Konrad]

I have machined S7 but pre hard for shear blades,...you'r at max. hardeness of this tool steel, not sure why you want to machine this?
Must be a re-work?...at only .055 depth it might be a perfect EDM job? Not something I would machine.

Konrad