Abstract: Thermal-vacuum tests are performed to evaluate the transmission performance of solid and grease lubricated XB1-60-150 harmonic drive. The effects of ambient temperature, output load, lubrication type, and operation time on the transmission performance of the harmonic drive are investigated based on orthogonal design method for multi-factor analysis，when the transmission efficiency is taken into account as an evaluation index. The transmission performance of the solid and grease lubricated harmonic drivers is studied under a range of temperature and rated load condition. The relationship of transmission efficiency of those to temperature and operation time is analyzed. After running 1.5×105 r of the wave generator, the morphologies of the gear teeth and the inner surface of the flexspline under different lubrication type are analyzed by using an optical microscope. It is found that the most important influencing factor on the transmission performance is temperature and the least important influencing factor is operation time. Lubrication type and output load are less important factors. In the temperature range of –40 ℃ to 60 ℃, the transmission efficiency of grease lubricated harmonic drive is better, however, the solid lubricated harmonic drive shows obviously more stable transmission efficiency. The gear teeth and the inner surface of both the solid and grease lubricated harmonic drivers’ flexspline show distinct traces of sliding movement after thermally-cycled test.

Key words: Harmonic drive, Lubrication, Orthogonal experiment, Transmission performance