Electro-polishing of tungsten carbide ball nose end mill to improve tool life

Abstract

Electro-polishing was used as an alternative to mechanical polishing for the cutting edge preparation of tungsten carbide (WC) ball nose end mills. High-quality cutting edge surfaces with roughness of magnitude 0.3–0.35 µm was achieved using the electro-polishing process. A direct current of 0.96 A was passed through an electrolytic cell containing the electrolyte sodium hydroxide with a concentration—2.5 mol/dm3. The ball nose end mill was suspended as the anode and a stainless steel (SS304) as the cathode. The ball nose end mill was electro-polished using the optimized parameters which was obtained through performing the preliminary experiments on tungsten carbide coupons of size D6 × 20 mm. The effects of electro-polishing on the surface texture of the ball nose end mill were determined using surface texture examinations. Machining tests were conducted on Ti6Al4V alloy to understand the growth of flank wear on the electro-polished ball nose end mills. After every 5 m of cutting distance, flank wear measurements were done for both the regular ball nose end mill and the electro-polished ball nose end mills. The results revealed that the electro-polished ball nose end mill reached a flank wear of 0.15 mm after a cutting distance of 550 m. This was significantly more than the cutting distance of the standard ball nose end mill of magnitude 350 m for the same amount of flank wear. This showed an increase in tool life of over 50%.