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

Retention Knobs are the critical connection between your machine tool and the tool holder and they are the only thing holding a steep taper tool holder in the machine’s spindle.

​Techniks has recently introduced their MegaFORCE retention knobs that have some rather unique features when compared to standard pull studs.  Before delving into the features of the MegaFORCE pull studs, let's review some things that you may not know, or think about, on a daily basis. 

However, if you're running multiple shifts, 24-7, making lots of tool changes, making very heavy cuts with long reach or heavy cutting tools, and/or have ball lock style grippers instead of collet type grippers used on the retention knob, you will probably need to replace your studs at least every six months.

Given the spindle speeds that we are running at to remain competitive, retention knobs are not an item that you want to take a chance on breaking.  I can tell you firsthand that 5 pound toolholder with a drill in it flying out of the spindle at 23,000 RPM is not something you want to experience. 

Pull studs encounter catastrophic failure as a result of metal fatigue. The metal fatigue can be caused by a number of reasons including poor choice of base material, engineering design, machining process, poor heat treatment, and, sometimes, they have just met or exceeded their service life. We're going to dig into each of these reasons below but first let's look at some threading fundamentals.

That is why the length of engagement of the thread on a pull stud is generally limited to approximately one to one & a half nominal diameter. After that, there is no appreciable increase in strength. Once the applied load has exceeded the first thread's capacity, it will fail and subsequently cause the remaining threads to fail in succession.

The most common failure point for a retention knob is at the top of the first thread and the underside of the pull stud where the grippers or ball bearings of the drawbar engage and draw the toolholder into the spindle.

Remember, bigger Radii are stronger than sharp corners. ​More on that soon.

Not all retention knobs are made from the same material, however, material alone does not make for a superior retention knob. Careful attention to design and manufacturing methods must be followed to avoid introducing potential areas of failure.

MegaFORCE retention knobs are made from 8620H. AISI 8620 is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to develop a case-hardened part. This case-hardening will result in good wear characteristics.  8620 has high hardenability, no tempering brittleness, good weldability, little tendency to form a cold crack, good maintainability, and cold strain plasticity.

There are some companies making retention knobs from 9310. The main difference is the lower carbon content in the 9310. 9310 has a tad more Chromium, while 8620 has a tad more nickel.  Ultimate Tensile Strength (UTS) is the force at which a material will break. The UTS of 8620H is 650 Mpa (megapascals: a measure of force). The UTS of 9310H is 820 Mpa. So, 9310H does have a UTS that is 26% greater than 8620H.

​That said, Techniks chose 8620 as their material of choice because of the higher nickel content.  Nickel tends to work harden more readily and age harden over time which brings the core hardness higher as the pull stud gets older. The work hardening property of 8620 makes it ideally suited for cold forming of threads on the MegaFORCE retention knobs.

​It should be noted that some companies are using H13. H13 shares 93% of their average alloy composition in common with 9310. 

Rolled threads produce a radiused root and crest of the thread and exhibit between a 40% and 300% increase in tensile strength over a cut thread. The Techniks MegaFORCE retention knobs feature rolled threads that improve the strength of the knob by 40%.  

In order to maximize the life of your retention knob and prevent catastrophic failure here are some technical tips to keep your shop productive and safe.

Special thanks for Greg Webb at Techniks and Mike Roden from Fette Tools/ Turning Concepts, for providing technical insights. 

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.

Tech Tip: Techniks and Parlec

Tech Tip: Techniks and Parlec

We have had several inquiries regarding steep taper rotary toolholders specifications.  Below you will find all of the technical reference information related to V-Flange Tolling Tapers and dimensions.

BT-40 Shank is also known as: JMTBA MAS-403 "BT", JIS B 6339 - 1986, JIS B6339 - 1992, and ISO 7388/1 - 1983.

The spindle interface JIS B 6339 as the traditional interface for milling spindles distinguishes itself through it robust design. Its field of application ranges from fine machining to heavy duty roughing. The tool holder is pulled in the milling spindle with the help of an additional pull stud.

The centering takes place via the taper contact. Therefore, the JIS B 6339 interface is primarily suitable for applications with a spindle speed of up to 12,000 rpm in an unbalanced condition.

Tech Tip: Techniks and Parlec

Many operators do not know why it is necessary to replace their tooling, or have the experience to tell when it is time to do so.

Determining if toolholder components need to be replaced is not a difficult task, but does require that the operator knows what to look for.

A worn out holder will not provide good accuracy and will quickly wear out your cutting tools. Worn tooling causes poor surface finish, and may damage your spindle.

This article will discuss the following types of causes and types of wear.

1. Spindle Mouth Wear
2. ATC Alignment Issues
3. Taper Wear / Fretting