Speeds and feeds refinement in sub-optimal situation

[andrewmb]

I've lurked the forums for awhile but decided to finally post as I can't seem to find a good answer to a question that's been plaguing me.

I'm doing some prototype work at a small company and long story short: I'm limited to what tools we have on hand to get work done.

The prototypes are being made out of 6061 aluminum and the only end mills I have available are:
1) 2mm 2F coated carbide
2) 6mm 4F coated carbide
3) 20mm 6F carbide

I've spent some time in Machinery's Handbook trying to make sense of the feed and speed tables but they weren't terribly helpful for a constrained situation like mine. From what I've seen here and other places, the best I can do is run at max rpm (10k for me)??

I'd really appreciate it if someone with more experience than I could help me understand what feeds and speeds to use with 6061 and these tools and especially WHY?? I understand that feed/speed is usually a very unique thing, but I'd be grateful if someone could go out on a limb and tell me what they would do in my situation so I have a reference to base my own plans on.

Other bits: machine is a sharp sv2412s w/ 10k spindle, FANUC 0i-MD, and flood coolant.

Thanks in advance!

[Geof]

Choice of speed is fairly simple; 10k for all the tool sizes.

Using coated carbide on 6061 is not optimal but if you have flood coolant it will be okay.

The thing you will need to watch is your depth of cut, width of cut and feed on the 4 and 6 flute cutters. These do not have much flute clearance for chips, especially the 6 flute, so you should keep the feed per tooth smallish such as 0.002" or maybe even less, the depth at not more than about half the diameter and the width of cut not more than about one third of the diameter.The lack of chip clearance is exacerbated by the coating which can make 6061 tend to stick and build up in the flutes until you just have a blob of aluminum spinning around.

Incidentally if you can do it, boost the coolant concentration up to something like 10%, assuming you are using water soluble coolant. This can help minimize the sticking problem.

[andrewmb]

Thanks for the reply, this is pretty close to how I've been doing it. Your suggestion on the depth is very helpful.

Incidentally, I'm using a fairly high coolant concentration already so maybe that's been helping.