Milling 6061 with max rpm of 1250.

[agfrvf]

Not happy with my finish with 8ipm using a 3/4 HSS endmill using max rpm1250. Looking to try 3" shell mill next. Suggestions on DOC and IPM and stepover would be apreciated.

 

[catsparadise]

If I want a nice finish on 6061 I'd use a flycutter for the final cuts. A piece of HSS sharpened with a generous nose radius in the flycutter, kerosene or WD40 over the part to stop chip welding. Your RPM is fine - I'd use 800+ rpm with a 2" dia cutter and take off 10 thou or less for the final pass. I'd reduce the feed rate though - I'd go for about 2 ipm.

With the flycutter you con do the whole width in one pass - depending on the part's dimensions of course.

Rob

 

[Karl_T]

My calculator gives 26 IPM for four flute and 13 IPM for two flute. Max DOC is totally machine dependent. Same with max step over.

In short move up your feed.

Bottom poor finish stone the corners of your endmill to make a tiny radius. Side poor finish - climb mill off a few thou on your last cut.

WD40 or kerosene does help.

 

[macardoso]

A new, sharp endmill will help your finishes.

 

[agfrvf]

Here is what I tried first and it worked.

With machine off Brought 3/4 4 flute endmill tip up to the work gently up to make contact. Moved cutter of the side. Set spindle to 1250rpm and table to 5ipm.

Finish had visual swirls but nothing you could feel with fingers.