[InspirationTool]

I'm milling some 1.5" deep pockets in aluminum with a 3 degree tapered end mill with a 1/8" tip. Obviously I'm getting some chatter problems

I've been using 6061-T6, but in my searches have found that 2011 should cut easier, but be more vulnerable to corrosion. The finished part will be exposed to high temperatures indoors. Strength is not a concern.

How much better is 2011 for cutting? How much worse is the corrosion aspect? Some light frosting shouldn't be a problem.

I'm planning on ordering from Yarde Metals or Admiral Metals.

I'm using flood cooling. Climb cutting seems to work better.

Anyone have any suggestions?

Thanks!

-Jeff

[Geof]

2011 certainly cuts much nicer; chips come off more like small flakes. If the use is indoors and dry the corrosion aspect probably will not matter, the greater vulnerability to corrosion is really only important if you are making something that will be exposed to weather or a marine environment.

If you are dealing with Yarde Metals ask about 6262. This is a free cutting alloy midway between 6061 and 2011. I have a chart that rates Machinability for 6262 at B with 6061 C and 2011 A. For corrosion the rating is 6262 - B, 6061 - B and 2011 - D. Perhaps more important Resistance to Stres Corrosion Cracking is 6262 and 6061 both A and 2011 - C.

6262 also cuts with small chips, not as good as 2011 but much better than 6061. It can also be anodized quite well whereas 2011 is not as suitable for anodizing, or so I have been told.

Strengths are comparable for all three; 6061 and 6262 are both 35,000psi yield and 38,000psi ultimate while 2011 is 38,000psi yield and 45,000psi ultimate. 6061 is a magnesium - silicon alloy, 6262 the same with lead and bismuth added while 2011 is a copper alloy with lead and bismuth added but I do not have the percentages.

[InspirationTool]

Thanks Geof! I'll look more into 6262.

-Jeff

[InspirationTool]

It looks like the 6262 isn't available in square bar from Yarde or Admiral...

[lerman]

I found that cutting with tapered cutters requires some extra thought. With a straight cutter, each pass cuts only the depth of the pass. With a tapered cutter, increasing the depth still has the entire length of the cutter removing metal.

I found it effective to first rough out the pocket with a straight mill. Then take the first pass with the tapered cutter opening it to the full diameter at the top. Leave just a small area for a final finish. There will now be a step in the pocket with the top at close to the final diameter. Then increase the depth for the next pass. The key is that only the bottom section of the mill should be cutting.

After this is done, a final finish pass can be made that will remove just a small amount of metal.

Ken

[Geof]

It looks like the 6262 isn't available in square bar from Yarde or Admiral...

Yes, we had to get our own die made and take minimum orders when we used rectangular 6262. It is only available in round as standard. But is 2011 available in square? I once tried getting it and was told it was not available standard in square.

[InspirationTool]

It looks like the only 2000 series available is square is 2024. Does anyone know how bad the corrosion resistance really is versus 6061?

Thanks for the tapered cutting tips Ken. I plan on doing some roughing with a straight bit. It's a bit ugly as I don't have a toolchanger.

-Jeff