The CoroMill Plura HFS range comprises two end-mill families, one optimised for titanium alloys and the other for nickel alloys. As chip evacuation and heat are specific challenges when machining titanium, Sandvik Coromant has developed a solid version for normal chip evacuation conditions, and another featuring internal coolant and a new cooling booster (patent pending) for optimum swarf and temperature control.
The end-mills for titanium are available in GC1745 grade and the geometry of the cutters is based on a six-flute concept with no centre cut, together with uneven tooth pitch. Additionally, the core dimension has been optimised for higher stiffness in titanium alloys, while the corner radius, rake angle and relief are all designed specifically for machining these challenging materials. For nickel alloys, grade GC1710 is offered.
“The new cutters are designed to offer high-feed side milling with large axial depths of cut (ap) and low radial depths of cut (ae), along with a controlled maximum chip thickness, so that the cutting forces are managed and provide a smooth cutting action,” explains Tiziana Pro, global product manager solid end mills at Sandvik Coromant. “The result is two-fold: increased productivity provides higher output, while greater tool life and reliability reduces scrap rates in what are typically high value components. Further customer benefits include reduced tool cost per component and greater safety levels.”
Target aerospace components include titanium wings and pylon parts, as well as engine cases made from Inconel 718. Applications in sectors such as oil and gas, medical and motorsport, where titanium and nickel alloys are becoming increasingly prevalent, will also benefit.
A customer trial was performed involving a LPT (low-pressure turbine) case made from aged Waspaloy 420 nickel-based alloy. Using a horizontal machining centre, axial depth of cut was increased and radial depth of cut reduced (high radial forces are known to create deflection issues). Comparing a 12 mm diameter CoroMill Plura HFS end-mill with a competitor cutter of the same size, metal removal rate increased substantially, leading to an impressive 198% increase in productivity. As a result of this success, the customer committed to ordering the new cutters.
