Indexable End Mills

[the penguin]

A question for Ken.


Are indexable end mills a viable choice for small hp vertical mills, in the 1-2 hp range?? If so, what insert design should we be looking for and again which ones to avoid???

[Mayhem]

Indexable insert face mills and shoulder mills

[the penguin]

(11-05-2012, 08:25 AM)Mayhem Wrote: Indexable insert face mills and shoulder mills

I'm talking about end mills in the 1/2" to 1" (12-25 mm) size range.

[Mayhem]

Sorry Jack, I misread your post. I guess I need to stop reading this forum on my phone.

[the penguin]

(11-05-2012, 08:57 AM)Mayhem Wrote: Sorry Jack, I misread your post. I guess I need to stop reading this forum on my phone.

No problem, maybe I wasn't clear in my question.

the indexable end mills can be dirt cheap, all the way to costly, are they viable?? or in the long run would it be better (and cheaper) to use regular carbide end mills??

I have a couple of cheap sets that use the CCMT inserts and a more expensive set that uses the AKPT inserts, there may be still better options. Being that I'm a hobbyist, I'm not sure which one to use where or if at all.

[Mayhem]

The advantage that I can see is in not having to mess about with jigs to sharpen end mills or the cost in sending them off the be professionally sharpened.

Of course, I'm sure they are not going the be the answer for everyone and there will always be situations where HSS will be the better option.

I will be very interested in what Ken has to say on this topic.

[EdK]

(11-05-2012, 09:52 AM)Mayhem Wrote: I will be very interested in what Ken has to say on this topic.

[PixMan]

Well....

Which you choose depends upon your applications and your budget. Good tooling doesn't cost...it PAYS. :) Of course I realize that a home shop would likely never see a return in terms of money in pocket, only the outpouring of cash to buy. There the return can be in lower frustration, better-looking parts, longer-lasting tools, less stress on machines, and many other intangibles.

I have tried many different styles of insertable end mills over the 35 years of machining behind me and have found that the key to success is in the insert design, top form geometry, grades and overall resulting cutting force in a given application. Since (for now) I have only a 1HP Bridgeport, I know that some cutters suck, others work well.

The WORST on any machine are those that use TPG style inserts. Most of those cutters hold the insert nearly perpendicular to the workpiece face, parallel to a shoulder. Those hammer your spindle hard, and use far more power than one with ADMT/APMT and similar style inserts, or those LNGX inserts on your 2" F4041 cutter. More often than not, TPG (and CCMT) inserts are made for turning applications and cannot take the beating of an interrupted milling cut. Moreover, the 60º included angle of the tips is weak and often is the first thing to break.

There are several different sizes (in general) of ADMT/APMT style inserts. Measured as the long edge, the smallest at about 8mm (5/16") and the largest at about 20mm (.787") As compared to regular HSS or solid carbide end mills, that's not a long edge. The attraction is in lower overall cost of using it and speed in getting a job done. Many of you say "speed doesn't matter" because it's a home shop and you have time. I'm the opposite, for sure. I want every minute I spend in the shop to be productive no matter what I'm doing whether it be making a part or sharing my experience with someone.

In general, I find that indexable insert end mills in smaller than 3/4" diameter rarely make sense. A 3/4" solid carbide end mill can cost between $50 (for crappy ones) and $200 for a really good, high-perfomance tool. By contrast, 3 inserts in a decent indexable might run you $36 and give you nearly the same performance and give you (at least) two edges.

I like the 10mm to 12mm size ADMT/ADGT/APMT inserts, as you can usually get three in a 3/4" cutter. A 5/8" cutter might take 2 of the same size insert, but when you drop to a 1/2" cutter body you can only get one bigger insert or two 8mm inserts. There, a decent $50 coated solid carbide end mill might make more sense as long as you're careful with it.

Look again at this photo posted in the other thread about face and shoulder mills.


The cutter at the far left is a Valenite V590A 13 125 WE17, which means it's a 1-1/4". Note that the inserts have a little shear angle, and a pretty good "chipbreaker" a.k.a. top form geometry to help curl chips and reduce force. Then there's the one about in the center of the front row, a 3/4" 3-insert cutter with black-colored inserts and black body. That's a Kennametal cutter that I think is now obsolete, though I can still buy ANGX10T308 inserts it uses. Notice that it has less shear angle, and less top form geometry. It uses more force than the bigger one.

Now here's the shear angle offered on the ADMT/ADGT inserts for Walter F4042 cutters:


Yeah, that's a bigger cutter but the inserts are the same used in the end mills. Now you see the shear angle is so much more. That's the way many newer cutters and inserts are made, and they work so much more like a regular end mill does because of that shear, or more appropriately, helix angle. No more hammering the spindle!

I do not recommend the Chinese made indexable insert end mills from the likes of Shars, CDCO or even our friend Jeff at Tools4Cheap.net. I think it's better to find bargains from eBay on newer, current tools from well-known name brands such as Walter, Valenite (now joined companies), Kennametal, Iscar, Seco, Sandvik Coromant, Ingersoll, Korloy and Tungalloy to name a few.

More questions?

[the penguin]

thanks, ken