the attempts where done with coolant, or airblast, seperate to avoid any drops of coolant to contact the cutter when dry. application of airblast was done by dissconnecting the coolant to the lockline manifold and apllying air. so 3 points of angle, tool holder did not have a significant rise in temp as i ade sure one of the blasts biasd the tool holder.
I did try a milling chuck (GS brand) with a reducer sleeve, mchined about 3 inches and shut it down due to the chatter death howel that came from it. i would like to try a side lock but alas the endmills are straight shank, not sure how i feel about angle grinding a flat when im lready breaking them! haha.
the hyd. tool holders are pretty neat and seem great besides the obvious breakage issues. definatly seem to dampen the cutting as advertized, good wall finishes and tolorance/runnout. there is no pull out as the depths have always remained good, but I do notice what i would describe as fretting on the endmill and sleeve, leading me to belive the flexture effect is struggling. of course the tooling rep said its the perfect holder for the job tho :p one aspect i do not like is that the actual clamping zone is (imo) far from the tool holder nose, 1/4" or more maybe wheras a collet is right at the tip.
you comments on "too much" clamping pressure is interesting, i could be curious what the pressure increase is from 25-50C working temp
MILLAND
as for the machine it is a 2009 vf2, but ony has 450 hours on it as i that in a university looking nice until i got it under a year ago. spindle runs true, drawbar seems way srtronger than the tm series i replaced it with. tapper is OK. i have noticed some lines on my tool holders comming doen the taper verticaly.
you comments on "too much" clamping pressure is interesting, i could be curious what the pressure increase is from 25-50C working temp
Jumped down the rabbit hole (In English and German) on Schunk tool holders and other related products,
very interesting indeed,
but haven't as yet found specific statement on what the actual clamping pressure and forces actually are ?
One thing that was interesting in the manual , was to say that don't tighten the tool holder without a tool (shank) being in the holder, (they don't say why) but presumably if you do then that has the capability to permanently deform the interior walls of the gripping part of the "Bore".
Gives an idea as to the forces involved,
I'm not familiar with the chemical composition and structure and (treatments thereof) of the Harvey (Kennametal) end mills [proprietary] but presumably some flavor / grain structure of cemented carbide ? ~
Being quite brittle. no free lunch for increased hardness in spite of some increased core "toughness".
^^^ The venerable "Bob" of the man of carbide - knows a lot about that.
I'm not sure if mechanically massive compressive forces acting radially inward on the shank would cause it to fail while the other end is being flexed and mechanically knocked about. *?
Couldn't find anything yet on temperature versus clamping pressure "Metrics" either ???? What happens if a Schunk hydraulic tool holder reaches 220 degrees Fahrenheit rather than 120 degrees Fahrenheit stated absolute maximum ? .
Interesting what MILLAND was saying about good for "Finishing" for hydraulics but Schunk Catalog all 790 pages + say it's good for everything lol (naturally) - some interesting stuff about calculating tool imbalances towards the end (around page 756 ) in a really easy way and exhaustively illustrated different scenarios that are worked through with their products yet nothing about clamping pressure and temperature issues. [Could act as very good reference for technical German vs. English ; bi-lingual document.].
Add links in a Mo'
Data sheets
Schunk data sheets on tool holders various + catalogs
Operating manuals
Schunk "Operating manuals" for tool holders etc.
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* this might not be the mechanism ~ but imagine if an end mill was made of glass, (precision ground rod) and you put it into a schunk (or other) tool holder and
really amped up the hydraulic pressure and knocked the end about a lot vs. having an identical glass rod that is gripped only with sufficient pressure and then knocked about... Which one will fail first ? Sort of an exaggerated concept for illustrative purposes of a severe concentration of stresses at the juncture of the tool holder versus the rod - but not unlike pre-stressed glass like materials ((Prince ?) - Rupert's glass exploding tear drops ). - Googling about there is this idea of brittleness and premature failure - for 'Solid" carbide endmills.
OTOH you mention slippage and fretting on the tool itself - suggesting insufficient grip ? ---> ? (will re-read thread)
The Schunk tool pressure test with the test bar seems 'Odd" as it there's no actual gradated measurement taking place ? Does the test bar slip with two finger pulling on it, but doesn't measure how much force can be applied under different conditions the other way i.e. tooooo much force ? ???
Schunk stuff seems really really nice,
Maybe you can call tech support at Schunk ? and then maybe Kennametal ?????