The 2021 Techniks Catalog is available for download now!!  It features the MegaFORCE Retention Knobs that we talked about in our February Article as well as the new Triton Hydraulic Holders. 

The only thing standing between a job well done and catastrophic failure is the retention knob. MegaFORCE Retention Knobs are designed to deliver superior performance and enhanced safety for the critical connection between your machine spindle and the tool holder.  Retention Knobs are subjected to extreme pulling forces of up to 5,000 ft. lbs. Over time, this stress exploits weaknesses in the retention knob and can lead to breakage.

MegaFORCE Retention Knobs have been designed and manufactured to increase the strength and durability of this critical connection.

​The longer overall length engages threads deeper in the tool holder, reducing taper swelling and maximizing taper/spindle contact for the most rigid connection. MegaFORCE also features a redesigned, blended radii for improved overall strength, making MegaFORCE the strongest high-torque retention knob in the market.

The Triton Hydraulic Holders by Techniks feature a new hydraulic design to provides excellent vibration damping properties, so tools run longer and quieter and produce superior surface finishes. Triton provides 3.5X clamping force of standard hydraulic chucks.

Triton hydarulic chucks are charged with hydraulic fluid in a vacuum chamber to eliminate air and gas from the system. Coupled with a redesigned oil sealing system, Triton chucks are built to provide maximum holding power for years!

You can page view or download the new catalog below!

by, Bernard Martin

As carbide end mills gain higher and higher speeds and metal removal rates there has also been a trend by round tool manufacturers to tighten up the tolerances on both the cutting diameter and the shank diameter to improve concentricity. At the same time, shrink fit holders have become more and more popular because they hold a tighter concentricity as well.  To achieve this both the shank and the bore now have similar surface finishes and this has led to a problem  The tools pull out in the cut.

Shrink fit holders are the most accurate for TIR as the toolholder engages completely around round shank tools with a bore tolerance of -0.0001" to  -0.0003".  As high performance end mills have tightened shank tolerances to the same range of -0.0001" to  -0.0003" they have used finer and finer grain grinding wheels which give the shanks a 'shiny' appearance. 

Shiny means that the superfinished shank has a lower coefficient of friction. So, although the TIR is tighter, the shank is more "slippery".   End mills traditionally had surface finish of about 8 μin on the tool shank. But that's changed.  It's been recommended that tool shanks used in shrink fit holders should not have a finish finer than 16 μin. for optimum holding power, but tell that to the guy who just superfinished the end mill to a super cocncentric tolerance that you don't want it looking that good.

Everyone know that the last thing you want is for the end mill to slip in the middle of a heavy cut or on the finishing pass of a high tolerance part.  These 'hi performance' end mills, often times have higher helix angles which are great for ejecting chips but also create a higher pull out force on that slippery shank. And reducing the helix angle is not the answer.

We  already know that the gripping pressure is a function of the interference between the tool shank  and the shrink fit toolholder bore. Most shrink fit holders have a already bore surface finish of between 12 μin. and 16 μin.  So they are ground to a very high tolerance and have about the same surface finish as the toolholder shank.

End mill manufacturers and machinist have tried a variety of methods over the years to stop the tools from pulling out. This has ranged from grit blasting the shank to rubbing chalk on the shank, but most everyone in the industry has felt that the problem really needs to be addressed by the longer life toolholder rather than the replaceable cutting tool.