ABSTRACT
Injection molding is a high-pressure process that was developed initially for molding thermoplastics but has been adapted for conventional thermosets and even bulk molding compounds (BMC). This chapter deals with general principles of mold design as they affect the operation of the molding process and the quality of the parts molded. When it is necessary to maximize precision and dimensional stability and to minimize warpage, it is necessary to maintain a positive control over all stages of the molding operation, from drying of the molding granules through the actual molding cycle and on to the final annealing operation. The overall economics will be determined by the specification of the feedstock, the levels set for production acceptance parameters, the cost of materials, labor, energy, and capital and maintenance costs of machines and molds. The plasticization rate is determined by the barrel diameter and length and by the design of the screw.
