Crack is one of the most common defects during injection molding, of which the main cause is stress and deformation. The stress mainly includes residual stress or external stress. When the crack develops more serious, it will lead to the fracture of the products, especially for hard alloy or ceramic products.

Definition

With filling: it means that the internal cooling rate of the injection blank is different from that of the outer cooling layer, which is inconsistent with the internal shrinkage rate after cooling. With filling is the phenomenon in which the green color is not a broken section, like the onion, the internal and external light color. The bigger the color difference is, the more serious the phenomenon is. Specific circumstances can refer to the following picture.

Definition: 

Porosity refers to the holes in the cross section of green bodies or products. When developing to a certain extent, the porosity will run through the green bodies. There are two kinds of porosity in injection forming: central shrinkage cavity and honeycomb pore. Contraction cavities can be seen in the following picture.

Cemented carbide powder has higher hardness, wear resistance and deformation resistance. These characteristics make it necessary to select a more refined process in the injection molding process. Within a certain range, the quality of the injection blank can be controlled by controlling the injection parameters.