Locking down performance

Since that time, the company has been busy developing, testing, and building the inventory of the Duo-Lock system which it promised even then to be the most rigid and most precise interface in the marketplace.

Today it’s even better, according to Thilo Mueller, manager of solid carbide end milling at Kennametal. Duo-Lock is claimed to be the only modular endmill solution able to compete at solid carbide levels and is said to outperform its nearest modular competitor by more than two to one. That means full-width slotting at depths up to 1x cutter diameter, and side milling up to 50% radial engagement at 1.5x the diameter depth, even in stainless steel, titanium, and other high temperature aerospace alloys.

Mr Mueller is excited about the tool’s robust machining qualities and is equally enthusiastic about its broad initial product offering. He says: “We have over 400 line items coming in the first wave, with many more coming early next year. These include the most popular size endmills in both imperial and metric, as well as a broad array of adapters, integral shank holders, and extensions.”

Many of those extensions are equipped with Haimer Safe-Lock technology, a secure clamping mechanism that eliminates concerns over tool pull-out and creep in high performance milling applications. HSK, CAT, BT, and comparable spindle tapers are also available.

One of the things that makes Duo-Lock beneficial is its intelligent thread design. Using FEA-based design tools, Kennametal has optimised the connection to eliminate any possibility of tool failure even at elevated loads. The result, says Mr Mueller, is that Duo-Lock handles 25% more torque than its closest competitor, permitting higher feed rates and axial depths of cut, especially in long reach conditions.

The cutting geometry uses an upgraded Harvi front end with an asymmetrical flute design. This breaks up cutting harmonics, reduces chatter and provides 20% or greater chip load per tooth compared to the solid carbide versions. The Harvi II five flute cutters have also received an upgrade: a variable helix known for its full slotting capabilities in titanium.

The eccentric relief behind the cutting edge with Harvi III is also a proven performer in titanium and other heat resistant alloys and is intended to satisfy the needs of customers looking for larger modular versions as well. Multiple carbide grades are also available, including Kennametal’s proprietary ‘Beyond’ grades KCSM15 and KCPM15, making Duo-Lock a go-to solution for everything from heavy roughing to semi-finishing.

“Because of the very small amount of tool runout, some of our customers are even seeing success in fine finishing applications,” comments Mr Mueller.

Assembly is reported to be a simple process: clean the Duo-Lock, insert and coupling, thread it by hand onto the adapter and torque it down. Since Duo-Lock is claimed to operate at higher cutting parameters than its competitors, the torque values are likewise greater.

Duo-Lock’s double cone locating surface provides Z-axis coupling repeatability of 10µm or better, and tool to tool repeatability is in the 50µm range, eliminating the need for offline presetting or tool touch-off in the machine.

And the additional contact surface at the base of the tool assures radial runout at the coupling below 5µm, improving run out at the cutting edge significantly, similar to the second contact area enjoyed by KM or KM4X customers. When the cutter dulls, customers can load it into a Kennametal Blue Box and ship it to one of the company’s reconditioning facilities around the world.

The result is a rigid, highly accurate tooling solution that offers greatly reduced set-up time and simplified tool changeover, cutting performance equal to solid carbide, and the stiffness to remove more metal in less time.

“We are understandably proud of the Duo-Lock design,” Mr Mueller concludes. “It’s an ideal solution for a wide variety of applications.”

KENNAMETAL www.kennametal.com/en/home