Ideal for stainless steels, but suitable for a wide range of materials, new Beyond MR (medium roughing) inserts from Kennametal are claimed by the manufacturer to be a ‘synergy of geometry and grade’ with smooth cutting action and high wear resistance.

Turning more parts per shift or extending tool life is a common ‘either/or’ trade- off for manufacturing companies but according to Kennametal, Beyond MR inserts deliver a combination of smooth cutting action and stable edge performance resulting in faster cycle times and long tool life.

Double-sided indexable inserts commonly feature four cutting edges per side with cutting edges facing away from each other. A chip step consisting of an inlet region and an outlet region usually separates each cutting edge. While these chip steps help to control chip flow and cutting action, the commonly fluted design of incremental inlet and outlet regions tend to be an area of concentrated stresses during cutting, shortening tool life. The differentiator with Beyond MR is based in part on designing the geometry of the chip step in a continuous curve so that alternating stresses are reduced.

The radius of curvature of the chip step surface is initially large, becoming appreciably smaller, constituting the inlet region of the chip step. From the lowest point of the chip step, the small radius of curvature grows larger towards the outlet region. As the surface of the chip step always has a curve, uniform chip forming occurs.

Chips tend to deform continuously within the chip step, minimising the friction of the chip on the tool face. Rake angle – the incline of the top surface of the cutting edge that makes contact with the chip – also helps control the degree of cutting forces and cutting edge strength. The Beyond MR insert has a high positive rake angle that works with the smoothly curved cutting edge to reduce cutting forces and extend tool life.

“In terms of chip flow, we believe it’s like nothing ever seen before,” says Jan Andersson, senior product manager, turning products at Kennametal. “Beyond MR’s rake profile, without the points of load concentration, results in an extremely stable insert body despite the high positive rake. Even with heavy depth of cut applications turning processes are safer and more stable, ensuring lower load on the machine tool and workpiece. Additionally, Beyond MR inserts also feature formed-in coolant channels that deliver flood coolant efficiently to the cutting edge. Improved heat control translates into smoother cutting and extended tool life.”

“More parts per hour or more parts per tool has been a longstanding conundrum for manufacturers,” says Manuel Sedan, senior product manager, turning products at Kennametal. “Running faster may mean process problems with chip wrapping or longer set-up times due to clearing chips from the machine. Plus, the days of one man one machine are long in the past. With one operator running a cell or any number of machines, greater predictability and performance with tools is an increasingly crucial component for success.”

Beyond MR is available in six grades covering a complete range of applications for turning stainless steel. Grades are also available for steels and cast irons.