Chesterfield-based Dormer Pramet (www.dormerpramet.com) has developed new chip-breakers for turning and bar-peeling operations.

The negative NRM turning chip-breaker is for roughing and semi-roughing of stainless steels and low-alloy steels.

Launched under the company’s Pramet brand, NRM is available for both double-sided and large single-sided inserts. It has been designed for high levels of productivity and is said to offer consistent performance and to accommodate high feed rates.

That said, NRM’s chip-breaking properties mean it can also be used for roughing stainless steel at low feed rates without the risk of work hardening, says Dormer Pramet. Its positive geometry with a wide T-land offers a broad depth of cut and promotes good chip evacuation.

NRM — available in grades T7325, T7335 and T9315 — enhances Pramet’s existing range of turning chip-breakers for stainless steel, including the NMR for medium to roughing operations, NM for medium turning and NF for finishing to medium turning.

In a recent test based on machining ISO M group material DIN 1.4301, the NRM chip-breaker on a CNMG insert (T7335 grade) achieved 60% more tool life than a competitor equivalent, says the company.

Meanwhile, Dormer Pramet has also introduced a new chip-breaker for the bar peeling of stainless steel, steel and super alloys. Suitable for roughing and finishing operations, MM has been designed with a wide strong T-land; this gives increased stability of the cutting edge and good chip control with an even spread of cutting forces, making it suitable for high-feed applications in heavy conditions.

There are three cutting-edge options: S01 for hard materials; S02 for medium hardness; and S03, which has a stabilised facet on the main cutting edge for soft materials.

The MM chip-breaker is available for use with LNGF and WNGF inserts for roughing and finishing, plus RNGH inserts for roughing. It is available in T7325, T9315 and T6310 grades.