Difficult-to-machine thermal spray coatings of Ni60 by ultrasonic vibration turning

       The piston pin of a construction machinery engine was scrapped in large quantities after being worn out. After being repaired by thermal spraying, machining was difficult. The material of the sprayed melt layer was Ni60 and the hardness was HRC60.



      The machining requirements of the outer diameter of the piston pin, the dimensional tolerance is 0.011mm, and the surface roughness Ra0.32μm~0.040μm, which cannot be met by general turning.

      Using ultrasonic vibration turning, the process parameters are as follows:

      Turning vibration frequency 20kHz

      Turning tool amplitude a=15μm

      Workpiece speed ν=4.8m/min

      Feed f=0.08mm/r

      Cutting depth ap=0.1mm

     The outer circle of the processed piston pin is measured, the dimensional error is 0.009mm, and the surface roughness Ra=0.16μm, which meets the requirements of the drawing.