Seco Tool getting chatter on Aluminium

[weaston]

Cutting: Aluminium
Tool Details: Seco Dia.10 4 Flute long series carbide endmill
(Seco Code: 91L100)

Seco Recomendations: Spin - 7000RPM (max. our machine can do)
Feed - 5600mm/min (Relevant to spin)
ap - 5mm
ae - 0.3mm

This produced a very poor finish (looks like chatter)
We reduced the feed to 2500mm/min much better, not as good as I had hoped. We then reduced spin to 6000RPM and feed to 600mm/min, this finish is good enough the problem is that it is now very slow.... The tool was bought with the intention of speeding things up, instead it is slowing us down.

Any suggestions to maintain speed but improve surface finish?

[weaston]

In my previous post I forgot to mention that a big contributor to our chatter problem is that the tool overhang is quite long. The cutter is sticking out of the holder by approx. 46mm.

[Billet Sean]

It's been my experience that when you get chatter, reduce the speed first. Too much speed and not enough feed will result in chatter. Also, is your work piece held rigid? If not, then that's a problem.

[dertsap]

in order to avoid chatter with a long series that has that much stick out it is usually best to keep a high feed rate with a heavy chipload ,the tool has less chance to chatter if the cutting edge is well engaged into the material

what could be happening and is probably happening is the tool is pulling itself into the material rather than a deflect at which either way you'll get chatter , so to create that happy medium you could try dulling the cutting edge very slightly(very slightly) as well ,sometimes the cutter being too sharp will cause the tool to grab and cause chatter . i know there are those that would try to argue the point but i have had to do this with many tools on many different types of materials with great success , sometimes a sharp tool isn t necessarily a good tool for the job

[Delw]

Dertsap.
exactly what I was thinking.
Same problem with sharp carbide tools in the past on Alum. what I do when running flimsy parts or I get chatter is take a piece of cold rolled steel and make 2 cuts on it then run the endmill on the alum.
with a almost 2" long flute length on that endmill you only need to cut the steel with the bottom inch of the endmill.
this wont dull the tool