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Mach Discussion => General Mach Discussion => Topic started by: mancman4 on February 29, 2012, 03:24:32 PM

Title: Speeds and Feeds with Micro end mills
Post by: mancman4 on February 29, 2012, 03:24:32 PM

Hi

I'm looking for some advice on typical spindle speed and XY feed rates when using micro end mills.

I know each manufacturer has slightly different specs so just ball park figures at this stage is fine.

I am cutting a 1 mm deep profile cut into hardwood using a 0.2mm square end mill.

What are typical feedrates for this type of cut....? Plunge rate....? and what depth for each pass...?

The end mills are too expensive to take the trial and error approach so any help is appreciated.

Thanks

Jason

Title: Re: Speeds and Feeds with Micro end mills
Post by: RICH on February 29, 2012, 05:38:37 PM

We imperialist's ( .008" dia end mill and .040" total depth ). The end mill will snap in a heat beat ( I'll assume carbide). SO very very slow plunge rate into the material, spindle speed of 20000 to 60000 rpm and cut depth maybe limited to no greated than the diameter of the end mill ....try .005". Clog the end mill and you'll break it. If you have backlash in any axis be prepared to break the end mill quickly. Feed in to fast and you'll bend the end mill and break it. Some spindle runout and you will break it. BTW what's the length of cut on the end mill? $20 to $30 each and it can get expensive quickly.

BTW, for folks reading this ,a human hair is like .003" dia so picture cutting wood or metal with a dirty hair.... ;D

Don't know what kind of hardwood as they are all different, grain, knots etc so a little practice on your part  for experience will surely help.

For What the above is Worth, ;)
RICH

Title: Re: Speeds and Feeds with Micro end mills
Post by: mancman4 on February 29, 2012, 06:14:22 PM

Thanks Rich

Some useful info there.

Like you say at $20 to $30 per end mill i can't afford to make too many mistakes...

I checked for backlash and runout and am confident my machine is set up well enough for this operation.

The length of cut on the endmill is 1.2mm (0.05") So i'll probably only take it to 0.035" (0.9mm) depth

Your depth per pass suggestions sounds like a good starting point.

I know the feedrate needs to be slow but how slow...?

By the way which has more strength carbide or HSS...?

Thanks again.

Title: Re: Speeds and Feeds with Micro end mills
Post by: RICH on February 29, 2012, 07:26:08 PM

I know the feedrate needs to be slow but how slow...?

Don't fool too much with wood so someone else may be of more help on the micro machining. Some of the exotic harwoods like Babinga, Ebony ( some has rock in it!),
Cocobola ( however ya spell it ) can get darn hard in spots.
The stuff i was doing was in 6061 Al and s/s, and i will remark that it's different than using an engraving type point tool.
By slow i think what would is important is that you let the mill cut into the material and not "plunge" into it because the thin end mill is not very forgiving.
If the spindle is good and you don't have much runout and enters the material perpendicular your less likely to have problems.
Watching under a microscope you can see them bend with little force when machining and you don't want that.

RICH

Carbide or HSS, each has it's pro's and con's and suggest you read up on the use. Old saying when designing is that a little ductility will go a long way as compared to hardness.