Hydraulic expansion chuck vs. Collet chuck

[gocuk]

Hi everybody,

I am currently looking for the drawbacks of hydraulic expansion chucks and collet chucks.

There is not so many sources telling about these. I have checked some engineering e-books and some articles and it seems that hydraulics are better than the collet chucks. But the comparisons on the articles are generally made between better quality hydraulic chucks and ER type collet chucks so it actually does not give an opinion since I am looking for the high quality collet chucks like Nikken and Kojex.

Vibration dampening, gripping force, rigidity, cost, spare parts, balance, lifetime, runout accuracy are the features i'm looking for.

What i know is that the hydraulic fluid in hydraulic chucks make a vibration dampening effect and collet for the collet chuck does the same effect also. One of the most important features is gripping force since the axial forces are much higher than radial forces in high speed machining. And gripping force of the collet chucks are better than the hydraulics. I am not pretty sure about rigidity. Hydraulics are cheaper and there is no need of spare parts. Collet chucks' inner structure are symmetric hence their balance is better. Runout is almost same for both.

This is what i could find out and i need to know more about it. Please share your views, knowledge and experiences. Thank you. Sorry for my average english.

[Deisman]

Hi gocuk,

We've created a guide to choosing toolholders that you can see at a glance the advantages & disadvantages of different holder technologies.

Toolholder Performance Guide –*How to Choose a Toolholder

you wrote:
What i know is that the hydraulic fluid in hydraulic chucks make a vibration dampening effect and collet for the collet chuck does the same effect also. One of the most important features is gripping force since the axial forces are much higher than radial forces in high speed machining. And gripping force of the collet chucks are better than the hydraulics. I am not pretty sure about rigidity. Hydraulics are cheaper and there is no need of spare parts. Collet chucks' inner structure are symmetric hence their balance is better. Runout is almost same for both.

I'd say:
The advantages of hydros is the rigidity and gripping force approaches what you can achieve with shrink-fit. Cost of hydros is more than collet chucks. disadvantages is hydraulic bladder can be damaged and/or leak. also can only use 1 size tool shank for tool unless use sleeves. Collet chucks are good when maintained well and easy to change to different size shanks w/different collets. good balance and runout should be achieveable with either tool. rigidity & gripping force of collet chucks may be reduced as collets age and/or pocket is damaged. Keep 'em clean & don't over-tighten the nut is good maintenance for collet chucks. collet chucks are not known for vibration dampening. hydro's are.

Hope it helps,

Deisman

[underthetire]

Are we talking mill tooling? Then you forgot heat shrink tooling.

[Astonlee]

Having carried out many tests on chucks hydraulic –v-mechanical –v-shrink –fit etc.
The first thing you need to understand is that hydraulic were originally design for high-performance/precision drilling & reaming applications. They can also cope with light/medium milling, but when use for having roughing they will deflect.
Tribos is an alternative hydraulic Toolholder system which is more similar to shrink-fit from Schunk but without the same clamping power of Shrink-fit!
Shrink-fit, give you high- accuracy/clamping forces but you need an expensive bit of kit to change the tools, and you lose the flexibility on shank sizes (Tribos has the same limitations).
Overall you will still find that a really good quality ‘Collet Chuck’ fitted with ‘Precision Collets’ does still provide you the best all round solution.
Regards
Alan
NB. If you want to run solid carbide ripper cutters, you must use a side-lock toolholder, as all the above holders will allow some micro-slippage of the tool causing the carbide rippers to fail.