Plastic toys

Plastic toys, as we all know, are toys made by the material of plastic. According to the plastic molding process, it is divided into injection molding toys, blow molding toys, rotomolding toys, slush molding toys, and inflatable toys. We mainly talk about the injection molding machine for toys here from the perspective of manufacturing process of them.

Manufacturing process of plastic toys

This article will take injection doll for example to explain the manufacturing process of plastic toys. Here are 4 steps to produce a plastic injection doll: filling- holding- cooling- demoulding. These 4 phases directly determine the molding quality of the product, and they are a complete continuous process.

Stage one- filling

Filling is the first step in the entire injection molding cycle. The time starts from when the mold is closed and the injection is started, until the mold cavity is filled to about 95%. In theory, the shorter the filling time, the higher the molding efficiency. But in practice, the molding time or injection speed is restricted by many factors.

Due to the fountain flow, the plastic polymer chain in front of the flow wave is arranged almost parallel to the flow wave front. Therefore, when two strands of plastic melt glue meet, the polymer( tyvek backpacks, a polymer bag ) chains on the contact surface are parallel to each other. In addition, the properties of the two strands of melt adhesive are different (different residence time in the mold cavity, different temperature and pressure), resulting in poor microstructure strength in the intersection area of melt adhesive. When the parts are placed at an appropriate angle under the light and observed with the naked eye, it can be found that there are obvious bonding lines, which is the formation mechanism of fusion marks. Weld marks not only affect the appearance of plastic parts, but also cause stress concentration due to the loose microstructure, which reduces the strength of this part and causes fracture

Stage two- holding

The function of the pressure maintaining stage is to continuously put pressure, compact the melt and increase the plastic density to compensate for the shrinkage behavior of the plastic. In the process, the back pressure is high because the mold cavity has been filled with plastic. In the process of holding and compaction, the screw of the injection molding machine can only move forward slowly, and the flow speed of plastic is also relatively slow. At this time, the flow is called pressure maintaining flow. In the stage, the plastic is cooled and solidified by the mold wall, and the melt viscosity increases rapidly, so the resistance in the mold cavity is very large. In the later stage of holding, the material density continues to increase and the plastic parts are gradually formed. This stage should continue until the gate is cured and sealed. At this time, the mold cavity pressure in this stage reaches the highest value.

Stage three- cooling

In the injection mold, the design of cooling system is very important. This is because only when the molded plastic doll are cooled and solidified to a certain rigidity, can the deformation of the plastic toys caused by external forces be avoided after demoulding. Because the cooling timer accounts for about 70% ~ 80% of the whole molding cycle, a well-designed cooling system can greatly shorten the molding time, improve the injection molding productivity and reduce the cost and vice versa. The cooling time can be tested by digital thermometer. Uneven cooling will further cause buckling deformation of plastic toys.

Several factors of influencing cooling rate:

• The design of plastic toys;
• Die material and cooling method;
• Cooling water pipe configuration;
• Coolant flow and nature;
• The selection of plastic;
• Machining parameter setting

Stage four- demoulding

Demoulding is the last link in an injection molding cycle. Although the product has been formed, demoulding still has a very important impact on the quality of the toys. Improper demoulding method may lead to uneven stress of the product during this process. For example, the meeting chair  or motion sensor will deform if demould improperly. There are two ways of demoulding: ejector rod demoulding and stripper plate demoulding. When designing the mold, the appropriate demoulding method shall be selected according to the structural characteristics of the product to ensure the product quality.

Conclusion: injection molding tool is important to toys

Owing to the injection molding machine, there are varieties of toys to be available. We just need to design different types of molds, so we can get toys of any shapes and sizes. Ningbo Lisong Injection Molding Technology Co., Ltd is a professional manufacturer of injection molding machine, for more products, please click here.