Injection molding process classification

The diversity of release products and the wide range of release problems make classification difficult. One approach is by product form, with subdivisions such as emulsions, films, powders, reactive or inert sprays, reactive coatings, and so on. Another approach is by application, eg, metal casting, mbber processing, thermoplastic injection molding, and food preparation and packaging. 

A further classification can be made on the basis of the fabricating process suitable for a given plastic. Each fabrication procedure requires certain rheological and/or chemical properties which, in turn, depend on molecular and supramolecular parameters such as constitution, molar mass, chain flexibility, entanglements, etc. In this system, a distinction is made according to whether the plastics are suitable for extrusion, injection molding. 

Extruders in the polymer industry come in many different designs. The main distinction between the various extruders is their mode of operation continuous or discontinuous. The latter type extruder delivers polymer in an intermittent fashion and, therefore, is ideally suited for hatch type processes, such as injection molding and blow molding. As mentioned earlier, continuous extruders have a rotating member, whereas batch extruders have a reciprocating member. A classification of the various extruders is shown in Table 2.1. 

---