The latest Sandvik Coromant grades provide the ability to perform medium-to-heavy interrupted cuts and remove the hardened layer (depth of cut up to 2 mm) in case- and induction-hardened steel components, typically for the automotive industry. Here, CB7125 and CB7135 offer longer and more consistent tool life, good levels of surface finish and consistent dimensional tolerances, says the company.
“For everyone working with transmission and other hard-turned components, there is a reason to choose these CBN grades,” explains Torbjörn Ågren, product manager - general turning at Sandvik Coromant. “Not least because adding value in speed capabilities and providing a more secure edge line and consistent tool life means lower cost per component. This is particularly the case when aiming for a one-cut strategy, namely a single cut with larger chip thickness, at high speed.”
CB7125 and CB7135 are optimised for turning steel materials with a hardness of 58-62 HRc. Designed for medium intermittent cutting, CB7125 features a newly developed PVD coating that provides improved wear and fracture resistance for extended tool life. This grade, which contains medium CBN content, is suitable for the turning of shaft splines and shafts with chamfered oil holes or pockets. Further applications include the facing of gears, the hard-to-soft turning of crown wheels, and the removal of hardened layers.
The CB7135 grade is pitched at the longitudinal turning of gears and shafts with un-chamfered keyways or pockets, as well as CV joint components such as the inner/outer race and cage. Featuring a high CBN content, the grade is said to offer high fracture resistance and predictable machining results.
Available for T-Max P, CoroTurn 107 and CoroTurn TR tooling systems, the grades come in both positive and negative basic shapes, with various edge preparations. Cutting data recommendations for CB7125 include a cutting speed of 100-200 m/min and feed rate of 0.05-0.45 mm/rev, while for CB7135, a cutting speed of 80-160 m/min and feed rate of 0.05-0.4 mm/rev should be achievable, depending on the specific application.
With the introduction of CB7125 and CB7135, Sandvik Coromant now offers a complete hard-turning solution, along with the existing and complementary CB7105 and CB7115 grades, which are suitable for continuous or continuous-to-light interrupted cutting operations.
