Machining accuracy requirements
The machining accuracy of the new die mainly includes three aspects: dimension tolerance, shape tolerance and surface roughness. Usually, the machining accuracy requirements for die manufacturers are mainly dimensional tolerance and surface roughness. Dimensional tolerance can be roughly divided into shape size and cavity size. These two kinds of requirements for the shape size of the die are relatively loose, and the actual processing size and the theoretical dimension error of the die drawings are not more than (+1.5mm) qualified. The dimension accuracy of the surface die cavity must be strictly controlled according to the drawings, generally not exceeding 0-0.1 mm. The surface accuracy of the die generally refers to the surface roughness. After treatment, the roughness of the die cavity is generally required to be 0. According to the actual product surface requirements, we can put forward the corresponding die surface processing accuracy.
Design of demoulding slope
Because of the shrinkage of SMC products after cooling, it will make the products tightly encapsulate the core of the die and the protruding part of the cavity. In order to remove the product smoothly and prevent the product from being damaged or scratched during demoulding, the internal and external surfaces of SMC products should have sufficient demoulding slope along the demoulding direction when designing SMC products.
In the design, the following two aspects should be paid attention to: (1) When moulding large SMC products, the stripping slope of the inner surface should be greater than that of the outer surface; (2) The commonly used demoulding slope is 1-1.5 degrees, or less than 0.5 degrees.