1. Gravity sedimentation. That is, the gravity of the impurity itself, under the action of physical gravity, the suspended impurities are precipitated by standing, which is relatively simple, but time consuming and inefficient.

2. Centrifugal filtration method. That is, the centrifugal force under the high-speed rotation of the centrifuge separates the suspended impurities, the colloid and the oil. The method has a short time and good effect, but the cost is relatively high.

3. Plate frame or belt extrusion filtration method. That is, through the plate frame or the belt filter press, the impurities in the oil material are separated by the filter cloth under the action of super-strong pressing force, the method is convenient to operate, short in time, and good in effect, and most grease equipment manufacturers often use this law.