Mechanical Properties of Components Injection-Molded from Thermosetting Molding Materials.

Plastics components manufactured from crosslinking molding materials in high-volume production were originally made by compression molding. For some time there have been thermosetting molding materials that can also be processed by injection molding. This has opened up new potentialities to processors especially in the automotive and electrical industries. The injection molding process is characterized by shorter cycle times than compression molding. The moldings produced have considerably higher service temperatures and show better dimensional stability than thermoplastics. This paper presents results of a test program in which strength properties of injection molded thermosetting bars were determined and evaluated. The report is broken down into the following sections: material selection; preparation of test specimens; shear modulus and damping as a function of temperature; strength under short-term load; limits at which initial damage to the material occurs; strength under static long-term load; strength behavior under dynamic long-term load; and effects heat treatment.