Plastics are gradually replacing glass in modern industrial manufacturing and consumer goods, particularly in optical devices and packaging. This transparent molding process requires extreme performance in terms of light transmittance, scratch resistance, and impact resistance. Therefore, achieving high-quality transparent products requires not only optimizing the raw material formulation but also meticulously controlling the vertical injection molding process, equipment configuration, and mold temperature.
To avoid internal stress and surface defects in products, the following seven key points must be considered during transparent molding.
1. Selecting Equipment Configuration Suitable for Transparent Materials
It is recommended to use an injection molding machine equipped with a dedicated screw and an injection nozzle with independent temperature control to maintain melt temperature stability.
2. Maintaining a High, But Safe, Injection Temperature
The plastic’s processing temperature should be set as high as possible while preventing thermal decomposition of the material to improve the plastic’s flowability and filling characteristics.
3. Properly Set Injection Pressure
Moderately increasing injection pressure can help overcome the resistance caused by the high viscosity of transparent plastics. However, excessive pressure can easily induce internal stress, making demolding difficult and even causing part deformation.
4. Optimize Injection Speed
Low-speed injection is recommended, especially if a multi-stage injection strategy of “slow start-up, fast fill, slow compaction” is used to help reduce internal stress and defects.
5. Shorten the holding time and the entire molding cycle
As long as the product does not exhibit voids or bubbles, the residence time of the melt in the barrel should be minimized to reduce the risk of degradation.
6. Key Adjustments for Screw Speed and Back Pressure in Transparent Molding
While ensuring sufficient plasticization, reducing screw speed and back pressure can help minimize melt thermal degradation and improve finished product quality.
7. Accurately Control Mold Temperature
Mold cooling directly affects the optical properties and smoothness of the part. Maintaining a high and stable mold temperature is recommended to achieve better transparency and surface gloss.
If you are producing clear plastic products, these adjustments for transparent molding are essential. They will not only improve your yield rate but also significantly reduce the cost of defective and scrap products.
