Need a better finish.

[Decomaster]

I am machining a .03" deep pocket in 6061 and the finish has to be nice and smooth. Right now it has swirl marks. I have tried both carbide and hss but both are the same. Any ideas? The part gets anodized so the finish cannot be very noticable. Thanks for your help.

[Guest]

Are they just visible swirl marks with no real feel to them? If so just run some scotch brite over them.

 

What is your finish requirement a 63, 32, 125?

 

If you are running the tool around the pocket you are going to have some tools marks. Very difficult to make it look like it wasn't cut with an endmill.

[Keith Graydon]

Ahhhh.

10k rpm 50ipm(or a little less)SHARP cutter, coolant. that should give you at least 32rms. check spindle bearings

-Keith

[Tim Johnson]

Try using a .005~.010 radius bull nose end mill. The scotch brite also does a really nice job.

[Roger Peterson]

Use an endmill with a corner radius on it, even a .005" corner radius will help greatly. Make sure you are using helical entry, even though it's only aluminum and you may not need it. And for your finish passes put something like .010 or .020 in your ramp height on the leadin and lead out parameters. This will get rid of the swirl marks where it goes into make the finish passes.

 

 

HTH

[deeherk]

not being a great mill man, all your answers sound good to me...would stepover help in this case???

dan

[Bob_Looney]

the corner rad is the ticket also, have the anodizer etch the parts

[Chris Rizzo]

You can play around with differnet types of pockets and stepover percnetages. True or Morph spiral are cosmetically "nice". Also uncheck keep tool down for finish passes. Select a point if you want the tool to enter in a specific place. Might want to try a finish depth pass at .005 or so, see what it looks like. Don't forget the ramp/helix entry. Try a good 3 flute cutter with the .005 corner radius. I like the M.A. Ford 3 fluters.

[chris m]

As CMR says, try leaving a little to finish on the floor; this will minimize any stepping on the floor caused by cutter deflection due to radial loads. If the surface area is large you may need to double-check that the spindle is square to the table as this can also cause steps.

 

C

[Decomaster]

I appreciate all of your info. The cutter is a bull nosed cutter w/ a .062 radius. The only places where the tool is leaving swirl marks is on the edges where the tool moves to start the next line. I don't know if that makes sence or not. The pocket has a shape similier to an eye drop shape. So on the large and small radius sides is where i am having the problems, not in the middle when the machine is moving in straight lines. Does this help?

[cadcam]

try using the pocket option of Spirial overlap so it cleans the step overs.

[HevyMetl]

Coming from the hardmill side. If I need a super smooth finish for a molding area I alway surface mahcine with a ball mill. You are talking about a big increase in time though. Your surface finish will be immaculent based off of your ball diameter and step-over.

[Chris Rizzo]

I know what your talking about deco. try true spiral, UNcheck inside to outside, check entry-helix, check follow boundry. That should enter follwing the boundry and spiral to center without any hard xy stepover moves. Takes some messing with though to get it just right.

 

hth.

[Decomaster]

Thank you cmr, what you said makes perfect sense. I havent been able to go out and try it yet and from the graphics it looks like i probably will need to play with it a little bit but i think it is deffenetly what I am looking for.

[Jim at Gentex]

One other technique if a 5 axis machine is used is to play around with the lead / lag angles to keep the center of the ball from dwelling on the surface. I can usually get a really sweet finish on aluminum without much effort.