Method for grinding large-size parts and grinding particles for use in the method for grinding large-size part

Petrochemical polymer material having a flexible specific weight ranging from 0.5 to 1.8 g per cubic centimeter and an elasticity rate ranging from 10 to 200 kg per square centimeter, or grinding particles (110) consisting of elastic natural materials (111) and whetstone particles (112), are projected towards surfaces of the shaped parts to be grinded at a speed having a velocity ranging from 600 m/min to 3800 m/min and a volume rate having a unit area of 5 to 300 cc per square centimeter per second to collide into the surface thereby causing sliding of the grinding particles (110) for grinding surfaces of large-size parts to be grinded.