An important technology breakthrough in specialist application turning and boring tooling by Sumitomo Electric Hardmetal’s development team has created a high wear resistant, nano-polycrystaline diamond indexable insert that is harder than single crystal diamond. This latest evolution in turning technology is capable of finish turning exceptionally hard, brittle materials such as cemented carbide, silicon carbide and tungsten-carbide cobalt (WC-Co) such as used in punches and dies that could only be machined previously using the grinding process.
The SUMIDIA Binderless NPD10 grade of insert is a polycrystalline isotopic diamond whereby the manufacturing process directly combines very fine (tens of nanometre) level diamond particles together without the use of a binder at the grain boundaries that can be subjected to degrade and failure at elevated temperatures.
As a result the SUMIDIA Binderless process has enabled the creation of a turning or boring insert that has a cutting edge harder than single crystal diamond with high levels of resistance to breakage and typical problems such as cleavability eliminated while having high orders of thermal stability.
Typical uses defined by Sumitomo include the machining of carbide dies and cutting tools plus processes involving, for instance, difficult materials used in medical, nuclear, instrument, military, such as armour piercing components and jewellery.
Successful operations include external turning of 50 mm diameter carbide die by 30 mm long. The turning machine was run dry at 20 m/min with a feed of 0.1 mm/rev and 0.1 mm depth-of-cut. When finish boring a carbide die with a NPD10 insert, the nominal 8 mm profiled bore size was machined at 15 m/min, 0.015 mm/rev and 0.07 mm depth-of-cut. Against previous methods, tool life was increased from three parts per insert to 15.
Website: www.sumitomotool.com
