To enhance milling performance on ISO S materials, cutting tool and tooling system specialist Sandvik Coromant is introducing a series of end mills featuring unique geometries and grades. The CoroMill® Plura HFS (High-Feed Side milling) ISO S cutters deliver reliable and productive results on workpieces made from titanium and nickel-based alloys, bringing benefits to both aerospace engine and frame applications.
To help address the predicted growth in aerospace business in the coming years, the CoroMill Plura HFS range comprises two end-mill families optimised for titanium alloys, and one 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, which is based on a tough, fine-grained (sub-micron), cemented-carbide substrate with sharp, controlled edges for very tough milling operations. Furthermore, a new multi-layer coating that contains silicon provides excellent wear resistance and low thermal conductivity. The geometry of the cutters is based on a six-flute concept with no centre cut and 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 deployed, which also features sharp, controlled cutting edges. A hard, wear-resistant, fine-grained substrate is optimised to resist high working loads when machining hard, highly adhesive, work-hardened materials such as aged Inconel 718. Here, a new coating produced with innovative HIPIMS (high power impulse magnetron sputtering) technology also offers adhesion reducing properties to avoid the formation of BUE (built up edge) and increase tool life.
“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.
To highlight the potential gains on offer, a customer trial was performed involving an 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 12mm diameter CoroMill® Plura HFS end mill against 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 has committed to ordering the new cutters from 1 October 2017.