Equipment and Technology for Combined Ion–Plasma Strengthening of Cutting Tools

Abstract

A combined strengthening of cutting tools for finishing has been carried out in glow discharge plasma filling a process vacuum chamber. At the first stage, reamers rotating around the axis distanced from the magnetron targets at 8 cm were bombarded by fast argon atoms produced due to charge exchange collisions of ions accelerated in space charge sheathes between the plasma and a negatively biased to 3 kV grid with a 25 cm radius of its concave surface curvature. The reamer bombardment by fast neutral atoms led to a reduction of its cutting-edge radius from ~7 μm to ~2 μm. At the second stage, the reamer surface was nitrided within 1 h at a temperature of 500 °C stabilized by regulation of the negative bias voltage accelerating the nitrogen ions. At the third stage, a 3 μm thick TiN coating has been synthesized on the reamer bombarded by pulsed beams of 3 keV neutral atoms at a 50 Hz repetition rate of 50 μs wide pulses. After the combined strengthening, the cutting edge radius of the coated reamer amounted to ~5 μm and the roughness of the area machined by the reamer holes in blanks made of structural steel reduced by about 1.5 times.