The process of injection molding is no simple thing, but if you are dealing with transparent plastic, then it gets even more challenging. There are lots of factors to consider, many of whom will be elaborated in the following part of the article.
Keeping Raw Material Dry & Clean
The raw material is the first thing to take into consideration when dealing with transparent plastic for injection molding. Any type of impurity in the plastic can harm the transparency of the final product. Therefore, it’s essential to mind the raw material at every step, starting on storage, transportation, and the feeding process.
Furthermore, it is essential to make sure that the raw material is free of any moisture. If there is moisture present, then that can cause deterioration when the material is heated. That is why, often, the raw material is dried. Once the raw material is fully dried, it can be safely used.
Clean Barrel, Screw & Accessories
Aside from keeping the raw material dry and clean, it is equally important to keep the barrel, the screw, and the remaining accessories free of any impurities. The best way to clean each component is with a screw cleaning agent. If there isn’t any screw cleaning agent, then PS or PE resin can be used instead.
Mold Configuration – Tips & Recommendations
There are a few things to take into consideration when designing a mold so that there is no uneven cooling or backflow of plastic. That way, we can avoid deterioration and surface defects.
- Walls need to be uniform and not too thin. In most cases, it shouldn’t be thinner than 1 mm. PET is the only exception.
- Vents need to be always clean and free to provide enough airflow.
- The mold’s surface needs to be smooth, featuring low roughness (ideally less than 0.8).
- Runner and Gate need to be short and large.
- All transitions on the part need to be gradual.
Tips and Recommendations for Improved Injection Molding Process
To reduce quality defects and minimize stress during the injection molding process, it is advisable to pay attention to the following aspects:
- Special nozzle temperature controls and screws are needed when we work with transparent plastic
- The release agent should be used as little as possible to prevent surface deterioration.
- If the plastic mold is filled in full, cycle and packing time needs to be as short as possible.
- The back pressure needs to be as low as possible for the best possible output.
- The plastic mold temperature must be carefully monitored and controlled, and if the circumstances allow it, the mold temperature needs to be high.
Injection molding of transparent glass is far from easy or straightforward. But once you figure out the steps, the way the materials are handled, the procedures, and all the peculiarities that accompany the process, it will turn into a routine task.
A routine task that will help you produce transparent products featuring excellent quality. Articles like this will speed up your learning process and help you avoid some of the most common mistakes done during the injection molding process.