Optimizing Milling - Speed, Feed & Depth of Cut

[palikalsi]

Hi All,

I have been working with CNC milling for about 4 months now. I have read so much about High Speed Machining and would like to know from the experts here if the principles could be used to optimize my programs.

I will start with a simple pocket and profile part. The finished part is 2.10" Long, 1.4" Wide, and .92" Deep. Material Used is Al 6061 and is 10" Long, 1.5" Wide and 1" Deep

I cut the part with the following operations:

Rough End Mill - 3/8" (.375) | Spindle Speed: 2500 RPM | Plunge Feed: 5 IPM | Cut Feed: 18 IPM

1. Pocket Depth: .570" | Level Depth: .230" | Tool Step: 80%
2. Pocket Depth: .770" | Level Depth: .230" | Tool Step: 80%
3. Profile Depth: .920" | Level Depth: .200" | Cut Feed: 20 IPM

These operations take 20 minutes for 4 parts in 10" material. Result is show below:


Later I use a finishing tool (1/4" End Mill) and cut additional .010" of an inch at 3000 RPM and 12 IPM cut feed. This takes additional 12 minutes.

Though I am satisfied with the time, I would like to know if anything could be adjusted to increase the finish of the final product or reduce the machining time. My machine has a maximum 4200 RPM spindle speed.

Regards,

Pali

[msomerville]

How many flutes on your 1/4 tool? If you are using carbide you can increase you RPMs. Since you aren't removing that much material with that tool I would use a 3 or 4 flute with plenty of coolant. The more flutes the faster you can feed.

[palikalsi]

I am using a 4 flute carbide tool. How fast do you think I should make it? Also, should I use HSS or carbide tools for aluminum.

Thanks, Pali

[msomerville]

I use carbide some use HSS. Carbide you can push harder, but some like HSS because they can achieve better finishes.
How fast can you run your machine?(RPMs)
I would run about 5000 rpms to start with 40 ipm.
You should be able to run faster than that, but that is where I would start.

[big_mak]

Run the tools as fast as you can.

I'd use Solid Carbide. You can get better finishes with SC than HSS due to Surface Speed.

On my machine, I am running 1/2" Endmills at 10,000RPM and 200ipm at .4" DOC MAkes nice chips. This is with a 3 flute endmill with variable helix geometry.

[Geof]

For cutters you should be using 2 or 3 flute high helix carbide; I find 2 flute gives better chip clearance.

For speed you should be running at your machine maximum for everything; see Big Mak's post he is running 1/2" diameter at 10,000 rpm.

For feed you should be running around .003" to .005" per tooth or 25 to 40 ipm.

You should be able to cut the time down to below 20 minutes combined for both roughinh and finishing.