carbide carbide carbide

Ever since we ran out of virgin tool steel, carbide has become the status quote, making it super cheap due to mass production.
And it does have its benefits.. rigid, higher cutting rates, better heat dissipation, longer lasting edge, blah blah blah.
But what about high speed steel? It's not so bad, it has its good points.
Semi flexable, able to have a sharper corner than carbide, resists chipping, and more forgiving on a crappy spindle, better heat dispersion, etc...
So the question is...is carbide always better? At least as far as end mills go.
I find myself going for the high speed steel mills when on the bridgeport. Iv'e yet to break one(not a cobb mill). I still have hss endmills in my box from 1986/1988 that will take as big a cut as I can crank the mill, even with a wrench on the handle. Yet I look at my carbide endmills from just 5 years ago or less and they all have tiny chips. Making them junk.
Seems we are switching to 100% carbide/diamond, but is that a good idea? A good example is high quality hand tools...they arent made of carbide or even hss, they are made of cold rolled steel. After heat treat they are hard on the outside, soft in the middle. Makes for a real strong, wear resistant, semi flexable, stable as hell tool. Best made tools in the world (herman Smidt) are all case hardened, to give the benefits of hardness without becoming brittle. Has anybody tried hss core with carbide outside, diamond coated? I know nitride coated has attempted to acheive this.
I just don't know why we stopped using hss on endmills, for some reason 99% of drills made are still hss?
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vinny wrote:

We still use HSS alot, usually when we break out the carbide is for either a long production job, or stainless..
(and of course to get out the taps the guys break off because they weren't paying attention)
I think one of the major reasons alot are switching to carbide is because of the higher SFM you can run them at, and life of the tool.
guess it all depends on the machine you have too.. if you have a highspeed spindle, and highspeed machining on the controller, you couldn't use its full potential with hss tooling (now this is just a guess in my part, but I really wouldn't want to run a hss endmill at 10,000 RPM 300+ IPM)
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Vinny, Ironic enough, today I suggested to a customer that they use a powdered metal endmill. It was a 1/16" diameter, needing to hang out of the collet a little further than what I would like to have it extend, he only has 5,000 RPM and it's a live milling unit on a Swiss Lathe and the part is away from the guide bushing further than what I would like to see it.
All of this adds up to not having a rigid setup. Not much SFM, cutting Titanium and the failure mode of the current carbide endmill was chipping.
I can put him into a coated Powdered Endmill that has a 1/4" Shank which will stablize it too.
Other options are High Speed Steel with Diamond Like Coatings that are inexpensive, very sharp, lasts very long while cutting aluminum and plastics.
On the turning side of things, try Cermets sometime instead of Carbide. Prices are not climbing as fast with Cermets as they are with carbide.
But all in all, if you have the spindle speed, the rigidity, and everything points to using Carbide, For endmills get the latest submicron substrate with some of the newest features such as Variable Pitch, Variable Helix, Nanno Coating styles like the V-7 YG-1 endmills, the Hanita Varimills and this style in whatever brand you may prefer, set them up in the ranges where the manufacturer recommends and do some fine tuning and watch these tools make you some money and free capacity due to the reduced cycletimes.
If you can't take advantage of the coating benefits due to not having the SFM, or the fixture is somewhat on the weak side, or it's a material where you need the absolue sharpest tool to cut it, HSS can still be the bread winner for you.
JR
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