Performance Evaluation of Lubricants Used in Gearbox of CNC Bending Machine

In this work, the performance of lubricants used in gearbox of CNC bending machine is investigated with different concentrations of nanoparticles. The base oil used is 20W40 which is highly suitable for planetary gearbox of CNC bending machine. The various types of oil samples are compared against different loading conditions by using a four-ball testing machine. Planetary gears have high reduction ratio and transmit high torque. The parts in the planetary gearbox worn out after a certain period of time and then break. The important parameters to be considered while selecting oil are viscosity, density and additives in the oil. Various nanoparticles are used as additives in the oil to improve its tribological properties. The base oil under investigation is 20W40 and the additive used is copper oxide (CuO) nanoparticle. Ultrasonicator is used to mix the nanoparticles in the base oil. The testing in the four-ball tester machine is carried out at 0%, 1%, 2% and 3% by weight of the nanoparticle. After careful observation, it is found that the mean scar diameter, torque and load-carrying capacity of the oil sample varies as the concentration of CuO changes. Optimum concentration of the nanoparticle is thus obtained for different loading conditions. For 126 kg and 160 kg loads, the optimum concentration was 1% by wt. of CuO and 3% wt.of CuO, respectively. At 200 kg load, welding occurred for all the concentrations of nanoparticles.