Thermosetting electrical connectors, oilfield electrical connectors, automotive electrical parts, these are just a few of the applications for thermosetting plastics.
In the past, thermosetting plastics were compression molded, which resulted in less accurate finished parts. Compression molding also is more labor intensive.
Injection molding of thermosetting plastics has opened many new applications and enabled designers to develop highly complex product designs. This is readily apparent in the photo above.
A high level of experience is required to effectively use this process. Though the injection molding process is similar to thermoplastics, it is, on the other hand quite different.
Higher melt temperatures, higher molding pressures, more abrasive molding operations, and higher mold temperatures are just a few of the unique aspects.
What are some advantages?
- Excellent dimensional stability. This is due to the chemical change that occurs during molding. When heated, the part maintains it’s size and shape.
- Great electrical insulators. Excellent dielectics.
- Good structural strength. This can be enhanced by using fiber fillers.
- Chemically resistant. Common chemicals have little effect, but some reducing agents and strong oxidizers can attack it.
- Excellent for Insert molding. Once the insert is molded in place, it is nearly impossible to extract it.
- Fire retardant. Very difficult to burn most thermosetting plastics.
- Extrememly rigid. This is due to the cross-linking chemical change that takes place in molding.
- Excellent for sound absorption. Might even drown out your teenagers hip-hop music!
Some disadvantages
Probably the biggest drawback is that these plastics are not recyclable. The runners and scrap cannot be reground and used again.
Another disadvantage is that not so many shops are skilled at molding these plastics. Neither are they equipped with the special presses or auxiliary equipment. There are many difficult obstacles to overcome and experience is the only good teacher.
Further reading
A good resource to learn more is at the website of Algix, a major compound resin supplier.
The leading company in China for molding thermosetting electrical connectors, and much more is Sincere Tech Plastic Molding Company. They have over 20 years experience and serve companies in the US, Japan, China, Europe, and Taiwan.