What are the failure modes of plastic injection molding?

1, Wear and tear failure
Wear and tear failure is one of the most common failure modes in plastic injection molding. During the injection molding process, the contact friction between the mold and the molten plastic can cause wear on the surface of the mold. Long term wear can cause changes in mold size and increase surface roughness, thereby affecting the dimensional accuracy and appearance quality of the product. When the wear is severe, it may even lead to the scrapping of the mold.
2, Fatigue failure
Fatigue failure is caused by crack propagation and fracture of the mold under long-term cyclic loading. Plastic injection molds undergo repeated stress loading during use, and fatigue failure occurs when the stress exceeds the material's fatigue limit. Fatigue failure usually manifests as cracks, fractures, or deformations on the surface of the mold, seriously affecting the service life of the mold and the stability of the product.
3, Corrosion failure
Corrosion failure refers to the failure of the mold surface caused by chemical erosion. During the plastic injection molding process, the mold may come into contact with chemicals such as acid and alkali, causing corrosion on the surface of the mold. In addition, certain components in plastics, such as solid fillers in thermosetting polymers and elements such as chlorine and fluorine in thermoplastic plastics, can produce corrosive gases when heated, further exacerbating the corrosion of molds. Corrosion can make the surface of the mold rough and even create holes, seriously affecting the accuracy and service life of the mold.
4, Thermal fatigue failure
Thermal fatigue failure is caused by the material experiencing fatigue failure due to thermal expansion and contraction when the mold works in a long-term high-temperature environment. Plastic injection molds need to withstand high-temperature cooling cycles during the injection process, which can cause stress concentration inside the mold material, leading to failure phenomena such as cracks, deformation, or fracture. Thermal fatigue failure is an inevitable problem of injection molds in high-temperature working environments, and effective measures need to be taken to prevent and control it.
5, Adhesive failure
Adhesive failure refers to the plastic material adhering to the surface of the mold during the injection molding process. As the number of injection molding cycles increases, the mold surface gradually becomes rough, ultimately leading to adhesive failure. Adhesive failure not only affects the appearance and dimensional accuracy of the product, but also increases the difficulty of cleaning and maintaining the mold. To prevent adhesion failure, anti adhesive agents can be coated on the surface of the mold or special mold materials can be used.
6, Deformation failure
Deformation failure refers to the deformation of a mold caused by significant injection pressure and temperature changes during the injection molding process. The deformation of the mold can lead to inaccurate product dimensions, poor appearance, and even inability to function properly. The reasons for deformation failure may include improper temperature control of the mold, unreasonable design of the cooling system, and excessive injection pressure. In order to prevent deformation and failure, it is necessary to design the mold structure and cooling system reasonably, and strictly control the injection molding process parameters.
7, Insufficient filling and flying edges
In addition to the above-mentioned failure modes, plastic injection molding often suffers from quality problems such as insufficient filling (i.e. insufficient filling) and burrs (sharp edges). Insufficient filling is mainly caused by improper feeding adjustment, insufficient injection pressure, temperature and time, low mold temperature or uneven distribution; Flying edges are caused by poor precision in mold manufacturing, unreasonable design, or improper injection process conditions. These issues not only affect the integrity and appearance quality of the product, but may also lead to mold damage and scrap.
8, Response measures
The following measures can be taken to address the above failure modes and quality issues:
Optimize mold design and manufacturing accuracy, improve mold wear resistance and fatigue resistance;
Strengthen the maintenance and upkeep of molds, regularly inspect the wear and corrosion of molds;
Reasonably control injection molding process parameters, such as temperature, pressure, and time;
Optimize the cooling system design to ensure even cooling of all parts of the mold;
Select appropriate mold materials and anti adhesive agents to prevent adhesion failure;
Strengthen quality monitoring and testing during the production process, promptly identify and address quality issues.