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View Full Version : Indexable end mill... As usual, it's more complicated



beanbag
07-23-2009, 01:03 AM
I ended up buying an indexable end /shoulder/face mill that uses the APKT style inserts. It's an Iscar E90A type, and looks something like this (not the exact model:

http://www.iscar.com/Ecat/datafile/PICTURE/1000.gif

It also came with a bunch of new inserts, called APKT 1003 PDR-HM.

http://www.iscar.com/Ecat/familyhdr.asp/fnum/31/mapp/ML/app/69/GFSTYP/M/lang/EN/type/1

Apparently, they are called "general use" milling inserts. Right when I got it, I had a feeling that it's not going to work well on my Bridgeport knock-off manual mill. Reason being that the inserts are not sharp around the edges, but rather slightly blunt. (I don't mean just the corner radius). I can run my finger over the edges, and it doesn't cut at all. (Sort of like a coated CCMT insert I had earlier). I'm guessing that the slightly blunt edges are for more strength, so you can just go blasting thru steels with interrupted cuts and other pathological conditions?

Anyway, what I have learned from reading other threads is that those of us with wimpy machines want as much positive rake and sharp edges as possible, to reduce cutting forces. Looking thru the Iscar catalog, I found these other inserts that may be better:

APCR 1003PDFR-P : HELIMILL super positive inserts with a polished rake for machining aluminum.

http://www.iscar.com/Ecat/illust_M/1145.gifhttp://www.iscar.com/Ecat/datafile/PICTURE/1145.gif
http://www.iscar.com/Ecat/familyhdr.asp/fnum/1145/mapp/ML/app/75/GFSTYP/M/lang/EN/type/1


APCT 1003PDR-HM : HELIMILL inserts with a ground cutting edge, used for finishing and high accuracy.
http://www.iscar.com/Ecat/illust_M/23.gif
http://www.iscar.com/Ecat/familyhdr.asp/fnum/23/mapp/ML/app/57/GFSTYP/M/lang/EN/type/1

(continued in part two due to image limit)

beanbag
07-23-2009, 01:04 AM
APKR 1003PDR-HM : HELIMILL 11 mm long, super positive inserts for aluminum, stainless steel and high temperature alloys.
http://www.iscar.com/Ecat/illust_M/26.gif
http://www.iscar.com/Ecat/familyhdr.asp/fnum/26/app//mapp/ML/GFSTYP/M/lang/EN/type/1/cat/3101884/relation/TI/tool/I

HM90 APCR 100304PDFR-P/DP : HELIMILL super positive inserts with polished rake for machining aluminum and high temp alloys. P=peripherally ground with a polished rake, DP=both periphery and rake polished
http://www.iscar.com/Ecat/illust_M/1778.gifhttp://www.iscar.com/Ecat/datafile/PICTURE/1778.gif
http://www.iscar.com/Ecat/familyhdr.asp/fnum/1778/app//mapp/ML/GFSTYP/M/lang/EN/type/1/cat/3101884/relation/TI/tool/I


HM90 APCT 1003 : HELI2000 insert with a sharp cutting edge, used for semi-finishing and finishing applications. Recommended for machining austenitic stainless steel, titanium and high temperature alloys.
http://www.iscar.com/Ecat/illust_M/1012.gif
http://www.iscar.com/Ecat/familyhdr.asp/fnum/1012/app//mapp/ML/GFSTYP/M/lang/EN/type/1/cat/3101884/relation/TI/tool/I

Note that none of these are APKT's. Also, I think the higher the "S" dimension in these figures, the higher the effective helix angle/rake.

So If I want to do aluminum, mild steel, and stainless, which one (or two) of these would be the best? I sort of have this notion that what works well in Al is high rake and sharp edges, but what is different about mild steel and stainless that requires a different geometry?

What is the difference between "ground" and "polished" edges?

tattoomike68
07-23-2009, 02:10 AM
Iscar is top of the line tooling, it will rip ass if you have a tough machine and run the hell out of it.
Do you have a high speed and HP tool to justify such tooling? (cnc)

If you have the tool to run it, just crank it full blast red line RPM, run it at rapid traverse and back it off till it growls and flings blue chips everywhere. Yea it will do the job faster than you want.

What are you putting it in and what type of job do you have for it? It just might be overkill, thats good but there is a limit.

G is a ground edge its good, P is a polished edge. go with the ground edge.

that type cutter cost bucks so you just get on with your bad self.

macona
07-23-2009, 04:07 AM
Try the standard APKTs. They work great! Especially in hard material.

I have a 1" 2 insert, 2" 5 insert, and a 4" 8 insert. Never have used the 4".

beanbag
07-23-2009, 06:41 AM
Try the standard APKTs. They work great! Especially in hard material.

I have a 1" 2 insert, 2" 5 insert, and a 4" 8 insert. Never have used the 4".

I think my APKT's are the "standard ones". I'm sure they're great for a CNC that rips thru material, but I have a regular ol Bridgeport. Are your APKT's sharp? Run your finger along the edge, and let me know: blood or no blood?;)

Forrest Addy
07-23-2009, 09:07 AM
Insert tooth endmills have cme a long way. They used to be stock removing "clubs" that featured heavy stock removal but little precision. You left finish stock then changed to a real endmill.

The newer insert tooth endmills BeanBag is asking work quite well but you still need a stout spindle to take advange of them. An R8 spindle plain doesn't have the beef. I suggest a #40 MMT at as a minimum. Yes, I know many of you with R8 spindles use them but when was the last time you checked the wear on your spindle taper?

Carbide cutting edges do not last long if sharp and keen particularly in iron or nickel alloys. They crumble, so to get better life the cutting edge is champhered or radiused to some fraction of the feed per tooth. This increases the cutting force but enhances the attainable feed rate and thus stock removal. If sharp inserts are available for insert tooth endmills I have no doubr they are intended for light finishing not stock removal. Read the manufacturer's info completely not just what the re-seller chooses to put in his catalog.

loose nut
07-23-2009, 10:50 AM
Carbide is weird.

I use the same TNMG inserts (these are lathe insert holders not end mills) that I use for steel on aluminum, I don't mean a new one of the same type, just the same one that I have been using for ever, and it works great and gives a nice bright finish. This goes against all carbide logic, tool geometry is all wrong but it does work.

My facing holder insert is all chipped and should be replaced but it gives a beautiful finish, don't know why and I don't care, it works when it shouldn't. When it doesn't that's when I will change it.

Carbide facts and figures are meant for industry where time is money. Try different types and see what works best for YOU, and when you get one that is good, go for it. Just be careful that you arn't hammering the heck out of your mill spindle.

lazlo
07-23-2009, 11:03 AM
What is the difference between "ground" and "polished" edges?

Most inserts are just sintered (molded). They have relatively dull cutting edges. Ground inserts go through additional edge prep -- they're put on a CNC grinder and the cutting edges are peripherally ground. Ground inserts have sharper cutting edges.

Polished inserts go through an additional honing step after grinding. These are razor sharp.

Note that the more positive the insert, the more fragile the edge, and the sharper the insert, the more fragile the edge. So the ground, high-positive inserts are very fragile and are designated for finishing operations in aluminum -- they chip really easily.

PaulT
07-23-2009, 06:47 PM
Contact the guy that runs this website - www.latheinserts.com , he sells mill inserts also. He'll give you a good price on the sharp aluminum style inserts you're after, he also has them in the CCMT style, I use them and they work great.

He also has good deals on insert mills, lathe tooling and boring bars, his name is Curtis, tell him Paul T. sent you.

Paul T.

mc_n_g
07-23-2009, 11:33 PM
I have been using APET 1003(yes they fit APKT holder without any problems) for aluminum. I have used them in .5, .625 and .75 holders. The edges are ground and the top is polished. The shape is sort of like a 'U' channel. The edges are real sharp. I order them from http://www.maxprotools.com/. I have no affiliation with the business other than ordering from them. They also have other APKT styles along with lathe inserts.

Here is a picture from their ebay site. They sell them relatively cheap.

http://i10.photobucket.com/albums/a140/mc_n_g/machinery/apet_1003.jpg

oldtiffie
07-24-2009, 03:40 AM
OK.

I will let the discussion on the merits and short- comings of inserts as cutter alone.

Assuming the mill is accurately trammed and that there is no lateral deflection due to cutting load, the end of the inserts will cut a flat surface.

If the edges of the insert are straight and the side cutting edges of the inserts are vertical, they will cut a straight and vertical surface.

If the cutting edges of the insert are not parallel to the spindle axis those "tilted" (side) edges will not cut a straight vertical face.

A well-ground cutter with parallel cutting edges (no "tilt" - as for a router TC cutter) or a helical cutter (such as the usual HSS milling cutter) will cut a vertical face.

beanbag
07-24-2009, 03:46 AM
I have been using APET 1003(yes they fit APKT holder without any problems) for aluminum. I have used them in .5, .625 and .75 holders. The edges are ground and the top is polished. The shape is sort of like a 'U' channel. The edges are real sharp. I order them from http://www.maxprotools.com/. I have no affiliation with the business other than ordering from them. They also have other APKT styles along with lathe inserts.

Here is a picture from their ebay site. They sell them relatively cheap.

http://i10.photobucket.com/albums/a140/mc_n_g/machinery/apet_1003.jpg

Not much helix angle, though?

mc_n_g
07-24-2009, 08:12 AM
No. That is why there is a lip at the bottom. I do have not problem with 'hammering' or with the cutting action. Surface is like a mirror unless a chip causes a swirl mark. You can easily see when it is time to change the insert.

DaHui
07-26-2009, 12:32 PM
Carbide is good. I have a seco two insert 3/4" mill that I use a lot on my bridgeport. It takes XOMX inserts...very similar to APKT. You won't be able to run at "full capacity" of the end mill but it will move metal and provide a nice finish. If you buy inserts on ebay they are in the $1-$5 range instead of $10-$15 and you won't have a bunch of half worn out HSS mills in a drawer somewhere.

Look up the manufacturers website for a guide on the insert nomenclature. Then buy inserts on ebay. They can be had super cheap and you can experiment with what works best with little financial risk.

I basically use two insert styles, one for both steel and aluminum and one for aluminum only. That is to say a very sharp insert that provides the best surface finish in aluminum chips very easily. A general purpose insert works fine on both aluminium and steel but you must keep in mind an insert with a relatively "dull" edge needs a minimum depth of cut to work properly. In terns of "general purpose," look for an insert with positive rake but it doesn't need to be razor sharp.

These inserts look dull, and they are dull, but I use this for my "mill it all" insert. The one I use for aluminum is only slightly sharper and has more rake.

http://www.brw.ch/i2cmsdata/brw/images100x100/F38840.jpg

exkenna
07-27-2009, 10:54 PM
Paul T., Thanks for the plug.

The APET's and APKT's are both parallelograms but the APKT's have a helical edge. There are a lot of private label versions out there now that some of Iscar's Patents have expired.

They're so cheap it's worth having both molded and sharp versions.
The 3/4" 3-flute version is ideal for a B'Port. If a decent radial DOC is used they can be very smooth as 2 inserts in the cut eliminates a lot of the "banging".

You'll throw that old TPG import cutter in the garbage after using one of these for the first time. ;)