Shrinkage is an enemy of metal clothes processors are facing, especially for high surface quality requirement of large metal products, clothes hook contraction is a problem.
So people have developed a variety of techniques to minimize shrinkage and improve the quality of products.
Position in injection molding parts thicker metal clothes, such as reinforced rib or bumps in the formation of shrinkage is more serious than adjacent location, this is due to the thicker area of cooling speed is much slower than the surrounding area.
Different cooling rate leads to the formation of a junction surface of sag, namely into the shrinkage mark.
This defect seriously limits the metal clothing product design and molding, especially the large thick wall products such as TV chassis and cant display shell, etc.
Strict for household electrical appliances, in fact, this kind of products must eliminate shrinkage mark, for toys such as the product with high surface quality requirement is not allowed to have the existence of the shrinkage mark.
The cause of shrink mark may have one or more, including processing method, the component geometry, material selection, mold design and so on.
The geometry and material selection is usually decided by raw material suppliers, and it's not easy to change.
But many other about mold manufacturers in mould design factors may affect the contract.
Cooling flow design, the types of gate, gate size may produce a variety of effects.
Small gate, for example, such as pipe gate cooling much faster than the cone-shaped gate.
Gate in early cooling can reduce inside the cavity filling time and thereby increase the chances of shrinkage mark produced.
For molding workers, adjust the processing conditions is a method to solve the problem of contraction.
Significant impact on shrinkage filling pressure and time.
Parts after filling, the excess material continue filling to compensate for material shrinkage cavity.
Filling stage too short will lead to contraction intensifies, will eventually produce more or bigger shrinkage mark.
This method itself may not be to reduce shrinkage mark metal clothes hook to satisfaction levels, but workers can adjust the filling conditions to improve the shrink mark.