SMC mold is a tool for giving complete structure and precise dimensions to plastic products, and are paired with plastic molding machines in the plastic processing industry. Due to the variety of plastic materials and processing methods, and the different complexity of plastic molding machines and plastic products, the types and structures of plastic molds are also diverse.
SMC molding is an advanced composite material molding method, and molds are the foundation of the SMC process. Good product quality is ensured by reliable molds, so the design of molds is particularly important in SMC molding work.
In the design process of SMC molds, the cavity of the molds should be designed according to the specific size of the product. In addition, suitable materials should be selected based on the product's surface quality requirements and demand. To ensure the quality and feasibility of the product, the shear edges and ejection system of the molds should be designed reasonably.
The design of the separation surface of SMC mold
The selection of the separation surface should consider the following principles to ensure that the product is easy to demold, guarantee product accuracy, strength, and easy mold processing:
The position of the separation surface should keep the product as much as possible on the lower mold after the mold is opened, making it easier to push the product out and simplify the top-out mechanism;
Minimize the damage of burrs to the appearance of the product while being easy to clear away the residual burrs;
Convenient for mold manufacturing and mold parts processing;
For products with high radial dimension accuracy requirements, the influence of burr thickness on product accuracy should be considered, taking vertical separation surface to ensure the radial accuracy of the product;
To ensure the strength of the product, avoid sharp corners and thin walls.
Separation surface design is crucial, and the product should be designed for separation early in the mold design process. Draw the separation design drawings to ensure that the product can be demolded smoothly and easily produced.
The precision requirements for processing SMC mold
The precision of SMC moulds mainly includes three aspects: dimension tolerance, positional tolerance, and surface roughness. The precision requirements that we usually ask mold manufacturers for are mainly dimension tolerance and surface roughness. Dimension tolerance is roughly divided into two types: overall dimension and mold cavity dimension. The former has more loose requirements, and the actual processing dimension and the theoretical dimension of the mold drawing should be within ±1.5mm to be qualified. The precision of the mold cavity size must be strictly controlled according to the drawing, generally not exceeding 0~0.1mm. We can propose corresponding mold surface processing precision according to the actual surface requirements of the product.
The demolding angle design of SMC mold
Due to the shrinkage of SMC mould after cooling, the product tightly wraps around the protruding parts of the mold core and cavity. To facilitate the smooth removal of the product and prevent collision or abrasion of the product during demolding, when designing the SMC mold, the inner and outer surfaces along the demolding direction should have sufficient demolding angle.