The pipe fitting mold process of the plastic parts produced by pipe fitting molds mainly includes four stages: filling-holding pressure-cooling-demolding, these four stages directly determine the molding quality of the product.

1. Filling stage

Filling is the first step in the entire pipe fitting mold cycle production process. The time starts from when the pipe fitting mold is closed to the pipe fitting mold cavity is filled to approximately 9%. The shorter the filling time, the higher the molding efficiency.

2. Pressure holding stage

The function of the holding pressure stage is to continuously apply pressure, compact the melt, and increase the density of the plastic to compensate for the shrinkage behavior of the plastic. During the pressure holding process, the backpressure is relatively high because the pipe fitting mold cavity has been filled with plastic. During the packing and compaction process, the screw of the pipe fitting machine can only move forward slightly, and the flow speed of the plastic is relatively slow. The flow at this time is called the packing flow. In the pressure holding stage, the plastic is cooled and solidified by the mold wall faster, and the melt viscosity increases quickly, so the resistance in the mold cavity is very large. In the later stage of pressure holding, the material density continues to increase, and the plastic parts are gradually formed. The pressure holding stage should continue until the gate is cured and sealed. At this time, the cavity pressure in the pressure holding stage reaches the highest value.

3. Cooling phase

In the molding of pipe fittings, the design of the cooling system is very important. Because molded plastic products can only be cooled and solidified to a certain rigidity, the plastic products can be prevented from deforming due to external forces after demolding. The molding cycle of pipe fitting mold is composed of clamping time, filling time, holding pressure time, cooling time, and demolding time.

4. Demolding stage

Demolding is the last link in a pipe fitting mold forming cycle. Demolding has a very important influence on the quality of the product. Improper demolding method may cause uneven force on the product during demolding, and cause defects such as product deformation when ejected. There are two main ways of demolding: ejector rod demolding and stripping board demolding. When designing the mold, choose the appropriate demolding method according to the structural characteristics of the product to ensure the quality of the product.