Grinding of WCrV steel shavings

Abstract

1. With the aim of using powder for making compact billets and tools, the authors studied the grinding of WCrV steel in ball mills and vibromills with addition of surfactants- machine oil and solutions of oleic acid in oil and CCl4. 2. Addition of pure CCl4 retards grinding in comparison with dry grinding. Addition of oleic acid to CCl4 accelerates grinding. The optimum additive was found to be a 10% solution of oleic acid in 0.05 liter of CCl4 per kg of shavings; this corresponds to a virtually monomolecular film of adsorbed oleic acid on the powder. Grinding for 40 h in a rotary mill gives a powder with a mean particle size of 0.193 mm (in place of 0.277 mm with dry grinding). 3. In the case of grinding in oil, the optimum addition was 0.15 liter/kg of shavings; grinding for 40 h gave a powder with a mean particle size of 0.171 mm. With an increase in the amount of oil to 0.05 liter or an increase to 0.5 liter, the grinding rate was less than with dry grinding. 4. Addition of 10% of oleic acid to the oil, with a total solution volume of 0.15 liter/kg of shavings, retards grinding; however, if the volume of 10% acid solution is reduced to 0.05 liter/kg of shavings, the grinding rate is somewhat greater than with 0.15 liter of oil without oleic acid (after 40 h the mean particle size is 0.166 mm). 5. The duration of grinding in a vibromill is approximately six times greater than in a rotary mill. 6. The hardness of particles ground to a given particle size in a vibromill is less than in the case of a rotary mill. 7. Industrial shaving scrap from R18 WCrV steel contains oil (the cooling liquid used in machining). Therefore the simplest method of accelerating grinding of shavings in ball mills and vibromillis is addition of 0.15 liter/kg of oil or a 10% solution of oleic acid in oil (0.05 liter/kg), which is more effective.