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hsk63 for hogging?

bryan_machine

Diamond
Joined
Jun 16, 2006
Location
Near Seattle
Oddly this does not appear to have come up before.

It is repeatedly claimed (and sometimes supported) that HSK works well for high speed milling. So for spindles faster than say 12,000 RPM hsk has an advantage over cat-40.

But what about slower speed operations? Slotting with a 1" endmill? Big face mills? (Assuming parameter appropriate for the actual spindle, and in the realm of common sense - I'm not suggesting running a 3" face mill on a 40,000rpm spindle.)

In short, can hsk hog?
 
From what I understand that HSK is all around better than the CAT equivalent. Hsk63>cat40 , Hsk100>cat50 in terms of rigidity. Our shop was all CAT until a new machine we got only had hsk or capto for options. We really like the HSK and will probably keep adding machines with that spindle. We do a lot of low speed hogging in tool steel with HSK and do not have any issues.

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No, no, and no.

HSK is not superior to CAT in all aspects. HSK was developed for high rpm spindles to alleviate problems with spindles growing and tools sucking up into the taper and seizing.

Don’t drink the Koolaid. Nothing beats full taper contact for heavy side loads roughing below 12K rpm.

X
 
I use my HSK63 for hogging all the time. I would bet good money that it beats a standard CAT40 easily in terms of rigidity.

In my anecdotal experience, when running hard metal machines, there was no comparison between CAT50 and HSK100 machines, the latter was WAY more rigid. Perhaps that was simply because of the builders, but I find that hard to believe. It seems like there is good reason HSK is replacing CAT with almost all of the premium builders.
 
No, no, and no.

HSK is not superior to CAT in all aspects. HSK was developed for high rpm spindles to alleviate problems with spindles growing and tools sucking up into the taper and seizing.

Don’t drink the Koolaid. Nothing beats full taper contact for heavy side loads roughing below 12K rpm.

X

Generally speaking I don't like to poo poo advice.... Especially from other respected members.

However, Koolaid it may be, the numbers don't lie. HSK63 has a higher bending moment capability than cat40, but I will say it is not much more, roughly 10%

Now along the lines of sir exkenna's comments, both have their place, but the taper face contact of the HSK is superior to the CAT connection in high speed applications, but that doesn't mean it doesn't have equal to or greater capability than the CAT at lower speeds. That is likely more going to rely on the spindle bearing layout and torque capability, as both will likely be vastly different. Keep in mind higher speed spindle bearings have to harness more force due to inbalance and therefore should in theory be designed stiffer / stronger than the lower speed machines.

One thing that many don't realize in the HSK format is you can convert these spindles to KM4X relatively easily as the ATC doesn't have to change, Kennametal proprietary it may be, it has roughly a bending moment capability 6-7 times greater than that of CAT40, this means bigger cuts with longer tools or far heavier cuts at shorter projections can be achieved utilizing more of the horsepower that once was only usable with large drills.

just my 2c, take it for what it's worth, not meaning to step on anyone toes or demean anyones opinion.

At the end of the day buy what you have budgeted for, can afford, and need, then run whatever you buy within its capabilities.
 
Have worked on machines that had HSK63 and CAT (non-dual contact) spindles, it always seems that the CAT spindle is stiffer. If I was attempting to explain it, the CAT configuration seems to take less than optimal cutting conditions better. Be it some awkward cored slotting configuation, or a small inside radius (cleanup of a trochoidal path or similar) the CAT will complain less than the HSK. Seems like I am always backing off on the HSK, where as the CAT will take more step over or depth of cut. The HSK spindle was in an Okuma MU5000, the CAT in an Okuma M560, so machine design may have something to do with it, but it doesn’t feel like a machine layout issue. Another plus for the CAT is that stubby holders are available, HSK cannot swallow a shank into the taper.
 
Oddly this does not appear to have come up before.

It is repeatedly claimed (and sometimes supported) that HSK works well for high speed milling. So for spindles faster than say 12,000 RPM hsk has an advantage over cat-40.

But what about slower speed operations? Slotting with a 1" endmill? Big face mills? (Assuming parameter appropriate for the actual spindle, and in the realm of common sense - I'm not suggesting running a 3" face mill on a 40,000rpm spindle.)

In short, can hsk hog?

.
when you have 10,000 rpm compared to 10 rpm the cutting force is literally 1000 times different when slower to remove the same cubic inches of metal per minute.
.
like a hydraulic jack can move slow putting 10 tons of force on something. obviously high forces can cause problems for machine, fixture/vise and the part
 
HSK is more expensive to produce than steep taper, and more expensive to own.

So, it is generally specified on high speed spindles, where it is really required.

The higher the spindle speed, the lower the tolerable spindle mass, inertia and bearing preload.

So, steep taper spindles are usually stiffer than HSK spindles.

This is completely separate to the interface itself.

It has been established that HSK is stiffer than steep taper.

Slower, high torque, high stiffness spindles with HSK will become more common in time.
 
I'm wondering why HSK spindles are more expensive to make, aren't they nearly identical to steep taper spindles? The angle is a little bit different but most builders have been making dual contact spindles standard for the last 7 years or so. The drawbar force on an HSK-63 is slightly higher than on a 40 taper dual contact spindle, and the gripper is internal instead of external. Other than the gripper, I don't see any real differences in the assembly.
 
The question that people don't ask often enough is whether the spindle taper is actually the limiting factor.

I think most of the time, the answer is no. You can only push a spindle of a certain size so far. Switching from dual-contact CAT40 to HSK63 isn't going to suddenly increase the load capacities of the bearings.

There are many other aspects of HSK that make them appealing, but they're a harder sell.
 
Anecdotal opinion. . .

The Hermle I ran was HSK 63, and would do every thing the CAT 40 Mazak’s would do. . . And more.

Is that a fair comparison. . . I don’t know? I didn’t run much soft material.
 
I can't speak to bending rigidity (we were drilling, not milling), but the big HSK spindles we used (Fischer/Precise) are ridiculously capable. I think it definitely makes a versatile machine. Your spindle can be high speed, and still have the guts down low to drill big holes. Last one I did, it was a 20k or 30k rpm spindle to do the small stuff, but could also do 3/4" holes through a 4" stack of titanium.

Outside of the woodworking/router world, it seems like a chicken and egg problem. HSK is more expensive, so no one buys it, which means it has lower volume, which means it's more expensive, etc., etc., etc.
 
OK, this has answered my question. Nobody here is claiming that HSK spindles are per force "glass cannons" that cannot tolerate heavy roughing. Rather there are a few voices suggesting that some cat-40 etc spindles may have an edge, some cat-40 holders come in useful configurations that hsk cannot match (have to check catalogs) etc. So for a general purpose machine HSK should be workable. Whether it will be optimal or cost justified is a different matter.
 
There is more to a spindle than the toolholder interface. I have seen a big brand machine with a cat 50 spindle that was not as rigid as the cat 40 on a different big brand. machine nearby. Bearing size, placement, and types. Spindle shaft size and length. So many variables.
 
Under 15K Dual Contact CAt40 > HSK63 > taper only Cat40

Over 15K HSK63 > DC CAt40 > Taper CAt40

It's not any harder than that. RPM dictates interface.
 
Under 15K Dual Contact CAt40 > HSK63 > taper only Cat40

Over 15K HSK63 > DC CAt40 > Taper CAt40

It's not any harder than that. RPM dictates interface.

That's what I've been going on too / thought ?

so

+1 lol.
 
what if youre at 15k exactly? :p

cat40 dual contact. 15K is an arbitrary number but after 15 the steps usually get bigger, and hogging isn't really the purpose of the spindle.

16 or 18K I'd still go cat40 dual contact, by the time I was at 20K I'd be looking at HSK.
 
cat40 dual contact. 15K is an arbitrary number but after 15 the steps usually get bigger, and hogging isn't really the purpose of the spindle.

16 or 18K I'd still go cat40 dual contact, by the time I was at 20K I'd be looking at HSK.

i know, that was a tongue in cheek comment ;)
 








 
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