The first processing tolerance is large, and the final processing tolerance is small (this is to ensure that the surface of the small tolerance size is not scratched and to prevent the deformation of the parts).
Arbutin is mainly extracted from the leaves of bearberry plants (also known as bear grape, bearberry, purple forest, is a plant of the azalea family Ursalis. The fruit is a red berry), and is now mainly used in skin care products.
Shell casting is a process method of making shell with resin-coated sand. Two shells bonded together to form casting cavity, melting iron water and pouring into casting cavity.