Causes and Solutions of Air Marks on Thin-Walled Injection Molded Parts

Causes and Solutions of Air Marks on Thin-Walled Injection Molded Parts

Thin-walled injection molded parts are widely used in various industries due to their high strength, rigidity, and lightweight. However, one common problem encountered during the production process is the presence of air marks on the part surface, which can affect the aesthetic appearance and quality of the product. This article will discuss the causes of air marks and provide solutions to avoid them.

Causes of Air Marks

1. Mold design: The improper design of the mold may cause uneven filling of the material into the cavity, resulting in air traps. The thickness of the wall, injection rate, and gate design are crucial factors that affect the filling process.

2. Material: The viscosity, flow rate, and moisture content of the material have a significant impact on the filling process. Materials with low viscosity are more vulnerable to air traps.

3. Processing conditions: The processing conditions, including injection pressure, holding pressure, and holding time, should be well-controlled. Large injection pressure and too long holding time can lead to gas compression, which produces air traps.

Solutions to Air Marks

1. Improve mold design: The mold should be designed with a larger gate, shorter flow distance, and thinner wall thickness to enhance the filling process.

2. Modify processing parameters: Adjust the injection pressure, holding pressure, and holding time according to the material characteristics and wall thickness.

3. Improve material quality: Use high-quality materials that are less prone to gas traps. The moisture content of the material should also be controlled within the specified range.

4. Purge the machine: Purging the machine before production can help remove any remaining gas in the barrel, which reduces the chance of air traps.

In conclusion, air marks on thin-walled injection molded parts can be avoided by improving mold design, modifying processing parameters, improving material quality, and purging the machine. By implementing these solutions, manufacturers can produce high-quality products with a smooth surface and excellent appearance.