Hard Milling Tool Steel

[Mark VIII]

Looking for a 1.25" dia holder and insert that works well in hardened D2 tool steel, rockwell 60. Anyone know of anything that works well? I plan on dynamic milling.

[mike93]

I would go with solid carbide end mills for hard milling (designed for hard milling) if its a shallow cut use a feed mill style cutter, if its (big) and shallow i now Iscar makes a insert for hard milling for the fast feed line. Use dynamic cutting all the way, if the insert or cuter is in the cut  to long the temperature  will max out the insert or the cutter and cause it to fracture. D2 is vary hard, but with the right tools and speeds its butter.

[jlw™]

Mike, would you be willing to post a link to which tools and what f/s work well?

[Mark VIII]

Thanks Mike. I will be side milling. I will probably choose am Imco Omega 6 endmill in that case.

[SlaveCam]

I asked the same a while ago, for machining case hardened 18CrNiMo. The answer was: sorry, we don't have anything (indexable). Solid carbide, as mentioned above, is your best bet.

Haven't tried Greenleaf yet, but they offer something that could be of use.

[MrFish]

yip solid carbide multi flute for side milling or feed mill for end milling, or Kennametal solid ceramic if you want to get fancy, personally haven't used one just seen them !

[Colin Gilchrist]

I've used the ceramic endmills from Kennametal in Inconel 618. They worked really well, but we were also slotting in between some blisk blades, so we were limited in the depth of cut we could take. I believe we ended up at 2400 SFM, with .100 DOC, using a .375 diameter cutter. The endmills themselves are crazy light. They almost feel like they are made of plastic, but they look really good with that bright orange glow during the cut. Like all ceramics, you'd swear they are burning up, but they cut well. I think we were leaving. 04 stock for finish, due to the heat affected zone of the material. The slots were about 1.25 deep, and .520 wide (it varied a little between the blades...).

A word of caution though; these cutters are not cheap. However, when looking at the price vs. performance, it was almost half the cost compared to solid carbide, when factoring in machine time.

[Mark VIII]

Colin, what kind of cutting tool life to you get with those?

[Colin Gilchrist]

About 20 minutes of "in-cut" time. That was at 90 inches per minute. I really would like to try some Dynamic Milling with these cutters, but haven't had a chance to do that yet. They worked fairly well for slotting. We had to stop about .180 from the floor of this particular part, due to the fillets at the blade root, and the heat-affected zone we were getting. The finishing was done with variable helix / variable pitch cutters, with a .120 corner radius, and was slooooow....

[Matthew Hajicek - Singularity]

I'm not sure ceramic would like dynamic.  Dynamic keeps the heat down, and as I understand it the ceramic works largely by melting the material out of the way, or at least heat-softening it.

 

Huh, I guess it works, maybe just have to drive it hard enough:

 

[Mark VIII]

That makes sense Matthew.

[Colin Gilchrist]

9 hours ago, Matthew Hajicek™ - Conventus said:

I'm not sure ceramic would like dynamic.  Dynamic keeps the heat down, and as I understand it the ceramic works largely by melting the material out of the way, or at least heat-softening it.

 

Huh, I guess it works, maybe just have to drive it hard enough:

 

One of the techniques I really want to try is "zigzag cut pattern" with Dynamic, in Inconel. The reason being that it would reduce the time spent "out of the cut", and hopefully keep the tool "in the cut". There is an option to use a smaller stepover value with the conventional passes, so I'd probably start with 60% of the 'climb' stepover...