Facemill and MT2

Success! I finally tested this 40mm APKT mill. I first had to make a MT2 shell mill holder with threaded drawbar (a long story for another posting). The 40mm, 4-flute, APKT major brand face mill was designed to be mounted on a 19mm shell mill holder with two driving lugs.

Conditions: BMS. 1mm depth of cut. 6mm width of cut at 600 rpm. For pacing the feed I counted at 1 turn of the handwheel in six seconds. The handwheel is marked with .100" per turn, so my maths put that at 1" per minute, (25mm per minute) which seemed very slow and difficult to maintain The work was to the front of the spindle, moving left to right. The spindle with facemill was behind the work cutting conventionally and the chips flying away from me.

Not knowing how best to proceed, I approached this test as if this were a HSS 4-flute endmill, right down to the width and depth of cut, sans cutting oil (I am not prepared to use coolant in a domestic setting).

The chips were small "c" shape and 1.5mm diameter, bright silver color. But, the chips sprayed horizontally, even into my toolbox one meter distant. I will have to set up a chip barrier to avoid this "chips ahoy".

The finish was good, but there was too much hammering for my sensibilities, which no doubt reflects on my inability to know how to use this carbide facemill. (I did try 900 rpm and double the feed, but the noise/hammering was louder). Hard to measure without a Db meter.

Does anyone know how best to use a positive-rake carbide facemill? All suggestions are welcome and appreciated.

Paul

Let's look at some numbers. A 40mm (1.57" face mill running at 600rpm gives a surface speed of 247sfm; in the right ballpark for carbide and BMS.

At 600rpm with a 4 flute cutter a feedrate of 1"/min gives a chip load per insert of 0.4 thou. That's way too low. The inserts will be rubbing rather than cutting. Therein lies the noise problem I suspect. I'd run at a load per insert of 3-4 thou.

A width of cut of 6mm times depth of cut of 1mm times 25mm/min gives a metal removal rate of 150mm^3/min, or 0.01 inches cubed per minute. That's very low; as a rule of thumb 1hp at the cutter should be able to remove 1 cubic inch per minute in BMS.

To start with I'd suggest upping the feedrate by at least a factor of five, then increase the width of cut to nearly the cutter diameter, and then try increasing the depth of cut, depending on how much horsepower you have available. I'd expect the chips to be coming off a deep blue or purple colour.

Regards,

Andrew

Andrew:

Thank you for your thoughtful response.

In your opinion, should I be using a different style of face mill?

Example: In MEW #139, Mike Haughton seems to prefer a face mill cutter with a square or octagonal positive insert (Diagram #11) and Photo 1 (the middle one).

Paul

The three tools in photo one are negative rake not positive, commonly sold as "little Hoggers" they work quite well though I prefere them for Iron than steel, this is the round one in action.

J

Edited By JasonB on 08/07/2013 19:05:40

Edited By JasonB on 08/07/2013 19:06:07

Paul

I second Dias Costa's face mill..RDG item ref 626 2MT 2" face mill. This is the one I have & use for most of the face milling I have done, & with the supplied carbide tips. As I don't have power feed on my WM 16 (2MT) I tend to look, listen & feel how the cutter is performing by hand feed, if it isn't shaking the machine to buggery & not squealing like a stuck pig, I carry on. I have had it cutting Aluminium, Brass, & CI with a d.o.c of 1mm (0.0397" if it floats your boat) quite succesfully as long as I am looking, listening & feeling what the machine is doing, & I alter the feed /speed accordingly. On black cold rolled MS & BMS I've cut quite happily with up to .5 / .6mm (.020" / .025".with chips flying off & 'HOT' (had a couple find their way down the front of my t shirt..'ouch' I carry on.

George

ps.. pic' of my cutter after machining CI with a .5mm cut  IIRC

I reset the set up after I had given the machine a good clean down after machining as forgetting to take pic for record purposes.

George

Edited By mechman48 on 08/07/2013 20:03:41

Paul: I see no reason why your face mill shouldn't work satisfactorily with APKT inserts, provided the inserts are proper branded items. The shape of the insert is largely dictated by the work being done. If you don't need to get into a corner then octagonal or round inserts might be a bit more robust and have more usable edges, but I doubt it'll make much difference on the smaller machine.

If you get the speeds and feeds right then your facemill should sing along. As alluded to by George when things are going well the chips come off hot. Hot as in it really hurts if you get one down the shirt, and they leave burn marks.

Up the feedrate and see what happens.

Regards,

Andrew

When In first got my face cutter, i was supplied whit inserts with chip breakers, but later when getting new inserts, the salesman(also a machinest)told me under no circumstaces should I use the inserts I started with, the non chip breaker inserts have a stronger edge, and withstand intermitant cutting better, the inserts I'd started with were lathe tool tips, but the new ones work ok in the lathe, After they have had their life in the milling machine, they get reground, and used in the lathe.  This is a new 16mm tip in a home made holder, the top edge is actually just a fraction negative.   Ian S C

Edited By Ian S C on 09/07/2013 14:56:38