[antonismel]

Hi to all. we have negotiatons for a new bridge machine. Eumach Co., Ltd.| Machining Center Taiwanese Manufacturer I never used HSK tool holders and I see that at this machine is optional. I have heard that HSK are better and I want to hear opinios. We are not going to work it for high speed maching.We want more torgue.Is there differerce in that point? what would you choose and why? thanks a lot.

[deadlykitten]

hy antoni hsk is better having also the flange contact, but be aware, that sometimes the vendors, even if they allow for option between bt and hsk, they are not paired, in the sense that it may be possible that the biggest bt has no hsk equivalent, while one size smaller bt has hsk equivalent

i would definetly look on the exact sizes of bt & hsk that they offer

the rigidity of the hsk is better than bt for small tapers, but at bt50, they are quite alike, and after that, on the theoretical curve, bt has the upper hand; on the long run, hsk toolholders may cost you more

bt50s are not for high speed machining, at least they are not to be reved at high rpms such as smaller bt's

as for torque, if there are different spindles, choose the one that has greater torque at common rpms; depends what the vendor offers; checking the link that you provided, i would ask for the spindle diagram for each unit, and available interfaces for each ( also 1st spindle type seems to be reasonable, 2nd may cost you more in the long term, while 3rd is for hard materials ) / kindly

[servtech]

Hi to all. we have negotiatons for a new bridge machine. Eumach Co., Ltd.| Machining Center Taiwanese Manufacturer I never used HSK tool holders and I see that at this machine is optional. I have heard that HSK are better and I want to hear opinios. We are not going to work it for high speed maching.We want more torgue.Is there differerce in that point? what would you choose and why? thanks a lot.

Hsk every time for me.
They run truer and machine more accurately, the tool clamps on a taper and the spindle face so has greater contact surface area. Better for high speeds and excellent for shrink tooling. The bigger spindles i.e. hsk30 and above also have internal drive dogs (keys) so do not lack heavy cutting capability. Fingers clamp tools up to 27Kn on average.

For slow speeds, rough/ intermittent cutting tough material machining, its probably better to use BT.

[servtech]

Hi to all. we have negotiatons for a new bridge machine. Eumach Co., Ltd.| Machining Center Taiwanese Manufacturer I never used HSK tool holders and I see that at this machine is optional. I have heard that HSK are better and I want to hear opinios. We are not going to work it for high speed maching.We want more torgue.Is there differerce in that point? what would you choose and why? thanks a lot.

Misread and didn't note HSK100. HSK100 are more than capable of competing with BT50 in almost all machining situations.

For long tools HSK will always hold tolerance better than BT. Can be coupled with much higher speed spindles.

[mactec54]

Hi to all. we have negotiatons for a new bridge machine. Eumach Co., Ltd.| Machining Center Taiwanese Manufacturer I never used HSK tool holders and I see that at this machine is optional. I have heard that HSK are better and I want to hear opinios. We are not going to work it for high speed maching.We want more torgue.Is there differerce in that point? what would you choose and why? thanks a lot.

This may help you decide HSK is way better in all applications, there are many Tool manufactures that will have real data which will suit your applications the best.

[antonismel]

Thanks for your answers.I have forgotten to say that I am talking about BT dual contact. I am asking about the torque because HSK 100 is more light weight tool holders.So that
it doesn't matter When the machine is working in low rpm conditions (1000-5000) the conditions are better for HSK?

[deadlykitten]

hy antoni, i guess you opted for the basic spindle ? still, it may not have yet enough torque at 1000, or at least not like at 2000, so i really recomand seeing the spindle diagram, kind of like attached

seems only 1st spindle takes bt, while 2nd takes both, so, if that is true, then your only option is bt

you should not worry about bt vs hsk at low rpms, definetly you need strong in-spindle retain force, and with a big toolholder, the spindle will stall, but the toolholder won't break

to take a decision, compare spindles diagrams and look over similar mactec's pdf from your vendor; however, in general speaking, the charts for bt are linear, while the charts for hsk are more curvy, this because in the hsk is more elastic behaviour ... thus the hsk is designed to be more "stable" than the bt, but it snaps peack once the forces getbigger, while the bt still has constant behaviour; in other words, if you push a bt too much, it will still take it, while a hsk may have doubts; this is how they sell : for common application range hsk is more stable, but as for high stress and fatique resistance, bt is the boss; most hsk vs bt charts, only reffer to simple bt, not dual contact, that's why i recomand requring such charts from your vendor

for heavy roughing, i see the bt50 dual contact as simple and stable, and not as expensive

on the long run, you may encounter problems with the flange contact, regardless of hsk or bt, so is needed much more atention to keeping the spindle face clean, and to avoid having chips from a toolholder jumping to the flange of another toolholder in the magazine, right at an atc change; definelty, you need to be more cautios / kindly

[servtech]

Thanks for your answers.I have forgotten to say that I am talking about BT dual contact. I am asking about the torque because HSK 100 is more light weight tool holders.So that
it doesn't matter When the machine is working in low rpm conditions (1000-5000) the conditions are better for HSK?

We have HSK100 spindles cutting aircraft grade titanium parts non stop. Many cutters within the 1000-5000 range. I don't see a problem.

[mactec54]

Thanks for your answers.I have forgotten to say that I am talking about BT dual contact. I am asking about the torque because HSK 100 is more light weight tool holders.So that
it doesn't matter When the machine is working in low rpm conditions (1000-5000) the conditions are better for HSK?

Thats the most important part, BT or CAT 50 dual contact will work very well, getting quality tooling will be your hardest part for the dual contact to be affective.

[deadlykitten]

just like mactec said, tooling quality is a must, and i wish to develop a bit : some preffer to buy their toolholders from a single source, in order to avoid variations that may cause :
... a new toolholder, from a different brand, to no longer make face contact
... or make good contact, but creates a different wear mark inside the spindle, that affects the stability of the other brand toolholders

dual contact toolholder relies on elastic deformation right before face/flange contact ocurs, so even if you inspect the dimensions of a new toolholder and they are ok, in the end is the materials&treatment that guarantess its proper function

at this moment, the only method i know for inspecting a dual contact is using a thin layer of a kind of paint, then clamp it in the spindle, unclamp, and check contact surface

anyhow, quality of such toolholders is higher than the one of single contact ones, and some toolholder brands may deliver different bt50 dual contacts, for example, in respect to what cnc machine brand is there; so, not all bt50 dual contacts are interchangable between different machines, as they may have different so called 'license'

quality of dual contact toolholders should not be easy overlooked, as it can have consequences

---

the conical/tapered contact must ocur towards the bigger diameter, and vanish towards the little one, and this, to be kept for as long as possible, requires that the toolholder elasticity is stable in time ....

having proper taper contact, and just in the last fraction of time, to make also face contact, is not easy, and also not a guarantee for the long time, especially for the bt; hsk can deformate more, while bt are more rigid, so this means that the elastic range of hsk is larger in comparison to bt, thus hsk can still operate at a level of spindle interface wear, where a bt may no longer make proper contact

somehow is normal, because hsk has shorter cone, while bt has longer; to fix this, nikken developed the 3lock system, that allows the bt to have increased elastic range, thus it is making the bt toolholder again stable at a point where, before, it was loosing it

the trick with the elastic range, is that the toolholder, must still be capable of traveling up the spindle, even after face contact occured, so is best to have a wide elastic range, and the flange contact to occur near the start, not near the end of this range; in time, elastic range shortens, and if contact ocurs near its end, then plastic deformation occurs during clamping

spindle issues with dual contact may be expensive, and may require also corecting the entire existing toolholders, so, when this happens, some preffer to corect their spindle in such a way, that it no longer delivers face contact, but only tapered contact / kindly

[mactec54]

just like mactec said, tooling quality is a must, and i wish to develop a bit : some preffer to buy their toolholders from a single source, in order to avoid variations that may cause :
... a new toolholder, from a different brand, to no longer make face contact
... or make good contact, but creates a different wear mark inside the spindle, that affects the stability of the other brand toolholders

at this moment, the only method i know for inspecting a dual contact is using a thin layer of a kind of paint, then clamp it in the spindle, unclamp, and check contact surface

No such paint is used, it is called Engineers Blue or Engineers Marking Blue sometimes called Bearing Blue also, it is nothing like paint.

Tooling must be orientated so that the tool Holder always goes in the spindle the same way. this is a must for Tooling like this using dual contact.

[deadlykitten]

enginers blue, yes, thats it mactec good tip also on toolholder orientation

We have HSK100 spindles cutting aircraft grade titanium parts non stop. Many cutters within the 1000-5000 range. I don't see a problem.

hy servtech, normally, there should be no worry, especially if the machine shows spindle load, so to have a clue how much is pushing; in adition, the spindle diagram indicates the sweet range for roughing, so if somehow a tool stalls at slow rpm, the chart will guide to a higher rpm, otherwise ... this matter only when going for high mrr, not light operations

I have heard that HSK are better ...

hy antoni just one more thing : if you may reach a point where to take a decision based on tooling costs, the bigger the parts that you will machine, the lower the worries; bigger parts pay better

good luck with machine negociation / kindly

[servtech]

No such paint is used, it is called Engineers Blue or Engineers Marking Blue sometimes called Bearing Blue also, it is nothing like paint.

Tooling must be orientated so that the tool Holder always goes in the spindle the same way. this is a must for Tooling like this using dual contact.

Absolutely, it is applied in a very thin layer and rubbing on a mating surface shows up high spots.
I used it for scraping surfaces and to find damage in bores and tapers. Worm and wheel mating surfaces and so on.

It's nothing like paint as you said.