Coating supplier Rushford Hypersonic (Rushford, Minnesotta) has applied its HPPD nanocoating to its first “real world” product, a drill bit. According to the company, the product performed exceptionally well during testing.
Initial testing included dry-drilling through ½-inch 304 stainless steel with no cooling fluid or lubrication using a ¼-inch-diameter jobber drill bit. After 238 holes, the drill was still going strong. To force failure, the drill was then applied to 1-inch 304 stainless steel, but managed drill 7 holes in this thicker material before it began to falter due to shank fatigue. The same uncoated drill bit completed only 6 holes in the ½-inch steel before failing on the seventh.
The first applications for the coating will focus on machine tools, mechanical parts and implantable medical devices. According to the company, the results of the tests confirm that the coating extends mean time between failure (MTBF) and can outperform other coatings on the market.
The characteristics of the coating are attributable to the HPPD process, which involves hypersonic deposition of nanoparticles ranging in size from 2 to 20 nanometers at a speed of mach 8. As the particles impact the drill or other item to be coated, they infiltrate and “stick” into the material, producing a weld-like bond resulting from a phase change in the nanoparticle on impact. The coating seals and protects the item with a thin film carbide with hardness ranging from 36 to 50 GPa and fracture toughness of approximately 6 MPa. Additionally, the dense coating formed by the nanoparticles fills pores and voids left behind by other plasma processes, making the product resilient and durable, the company says.