The medical mould for plastic injection molding must be produced and processed in conjunction with the relevant molding equipment to ensure its complete structure and precise dimensions. The molding process primarily involves the following two basic parameters:

1. The accuracy of mould dimensions. This parameter must be set appropriately, taking into account the design, processing, and molding stages of the mould based on drawings. The key here is to ensure that the actual mould dimensions fall within the dimensional tolerance range specified in the drawings, which designers need to handle properly; otherwise, it may harm the mould.

2. Shrinkage rate. Even with the same type of resin, if the molding conditions differ, its shrinkage rate will also vary. During mould formation, it is required that the shrinkage variation rate be small, and the expected shrinkage rate should be as close as possible to the actual shrinkage rate. However, this is often difficult to achieve in practice, and corrections to the mould are usually made after trial molding. To better correct the mould, when designing the concave dimensions of the plastic mould, the shrinkage rate should be set to the smallest possible value, while the convex dimensions should be set to the upper limit.

After familiarizing ourselves with the basic parameters of medical plastic injection moulding, we need to look at how to effectively prevent molding deformation issues using these parameters. Typically, deformation in such plastic moulds is mainly caused by uneven shrinkage and internal stress in the mould. Therefore, the preventive measures we can take include:

(1) The number of gates should be appropriate, and each gate should remain stable;
(2) Select the correct gate shape and position, which can be determined based on the mould shape.

Of course, to better prevent deformation of the medical plastic injection mould during demoulding, we should note that if the material has a relatively low shrinkage rate, attention should be paid to the fact that when the molding pressure is high, the plastic part is easily left in the mould cavity. In addition, during mould design, demoulding should be carried out without deforming the plastic part to avoid causing deformation.