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Cat-40 vs HSK-a63 Holders


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What is the consensus/preference in tool holder taper for a 20K spindle?

Cutting mostly (90+%) aluminium (majority surfacing) with tool extensions reaching into 12" long and diameters of up to 2" dia (some occasional 4" dia side milling cutters)

Most material removal/roughing is done by a 1.5" dia 3fl indexable em with different lengths.

I get some conflicting info from sales reps as well as users saying there is no advantage of a newer hsk over cat at those speeds.

 

 

TIA

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HSK all the way

The nature of HSK retention means the faster the spindle is going, the more centrifugal force

the grip pads apply to the tool holder, because gripping force is applied from the inside out.

The gripper on a Cat40 pull stud are just the opposite.

The faster the spindle goes the more the centrifugal force works against the grippers.

This was one of the primary reasons for the original HSK design

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Another advantage to HSK

at high RPM's the taper of the toolholder expands into the walls of the spindle

At high RPM's a Cat40 spindle actually expands a microscopic amount, but it's enough to

effect runout and gripping strength

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  • 2 years later...

Reading the link to HSKWORLD I noticed this paragragh

"When a tool collision occurs using a conventional, steep-taper shank, the potential damage can be considerably greater than is true when using an HSK shank. Because a CAT (SK, BT) shank is solid steel, most of the collision load (and damage) transfers to the spindle. With its hollow design, however, the HSK shank acts as a fuse during collisions. When a cutting tool crashes, the toolholder breaks off and protects the spindle, thus reducing repair costs and machine downtime."

 

Has anyone experienced or heard of a crash were the holder broke off and saved the spindle ?

Thanks, Eric

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2 hours ago, sweeper said:

Reading the link to HSKWORLD I noticed this paragragh

"When a tool collision occurs using a conventional, steep-taper shank, the potential damage can be considerably greater than is true when using an HSK shank. Because a CAT (SK, BT) shank is solid steel, most of the collision load (and damage) transfers to the spindle. With its hollow design, however, the HSK shank acts as a fuse during collisions. When a cutting tool crashes, the toolholder breaks off and protects the spindle, thus reducing repair costs and machine downtime."

 

Has anyone experienced or heard of a crash were the holder broke off and saved the spindle ?

Thanks, Eric

WOW. I'd have thought if you tw4t a holder THAT hard, you're spindle is toast anyway?

Previous place we had 2x Hitachi VS50's which both had small side bumps (holder shanked out) and both times the pull stud snapped.

Tool dropped a little but the spindle kept spinning so the taper was toast.

For the HSK statement of the holder snapping, the tool can't actually go anywhere down (ie drop away from the taper) so the spindle will still be rotating and the broken holder will surely still be "inside" beating the taper to hell?

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Big kaiser spindles can use face taper locating tool holders.

 

Our matsuura have the big kaiser spindle in bt40.

Out yasda Is hsk32 and the er25 holders look almost silly. The nut is bigger than the taper.

 

But for light cuts and mold work it's probably better than cat or BT 30

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  • 2 weeks later...

HSK tool interface may have the advantages quoted above, especially at speeds over 20K RPM. But they are not very good fuses. We repair spindles and we have seen several HSK crashes where the taper was  totally destroyed; so much so that whole shafts had to be replaced.  If there is a hard crash taper restoration work is virtually guaranteed, HSK or not.

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