Āhuahira Hangarau:

Ko tenei miihini he miihini huri with 4 planetary gear train motion principles. 

The grinding disc rotates counterclockwise, and the lower grinding disc rotates clockwise. The star wheel is driven by the inner cylindrical gear (the inner gear does not move) and the sun gear to make a unique revolution between the upper and lower grinding discs. And the rotation of the planetary motion. Therefore, the grinding motion with coordinated speeds in the four directions is formed on the workpiece. With this design structure, the relative linear velocity of the upper and lower surfaces of the workpiece remains the same.

The movement trajectory and the movement trajectory of the upper and lower grinding discs do not overlap, and can be uniformly ground at the same time.The upper and lower surfaces, the precision of the parts after grinding are high, and the production efficiency is much higher than that of the previous types of mīhini hurihuri.In addition, because the upper and lower grinding discs rotate at the same time, the movement resistance of the star wheel is small, andthe processed workpieces, especially those processed with thin and brittle materials, are not easily damaged.