View Full Version : Horsepower to run endmill

12-22-2008, 04:15 PM
Is there a method/formula to find the horsepower needed to use an endmill? I would know the number of flutes, the diameter and the Speed.
There will be more questions forthcoming.

12-22-2008, 05:24 PM
There is some data in machinery's handbook, for drilling, and depending on the edition, other machining operations. Maybe you could convert to HP/cubic inch/minute and use as a starting place.

12-23-2008, 11:15 AM
Here's a page on figuring it, provided you have the appropriate material data:



12-23-2008, 12:08 PM
Here you go;


Dave J.

loose nut
12-23-2008, 02:25 PM
If you use this link there are more of the same type of calculators for lathes etc.


12-23-2008, 04:41 PM
I think that would be hard to figure as a standard.

First, there is the DOC and the DOC of the side cut.

Second, there is the feed used during cutting.

Third, there is the material to be cut and all would have different resistances to cutting.

Fourth, there is the type and sharpness of the endmill.

Fifth, there is the coolant used.

Sixth, there is the internal friction of the machine doing the work.

I don't think you can quantify a given hp to use an endmill and any attempt is wishfull thinking.

12-23-2008, 06:20 PM
it equates to removal rates; for a given material there is a correlation between ci/min and hp. you're on your own for the formulas though, they're out there somewhere on the web as i recall seeing them

Rich Carlstedt
12-23-2008, 09:03 PM
In Manufacturing Engineering ( which I retired from) we used
one cubic inch per minute removal to equal one HP in steel

So if you had a 1/2inch endmill that had .25 DOC (depth of cut)
you would need to cut ( 2 x 4 x 4) =16 inches of travel in a minute to
reach one HP
Now if your desired tooth load was .0015 per tooth (.003" per rev),it
would mean 16/.003= 5,333 rpm on a two flute
That is not realistic, so changes must occur.
You will find that "drilling" more closely challenges the Horse power factor.


Use 3 cubic inches for Aluminum per HP per min.