Injection and micro injection of polymeric plastics materials: a review

The explosive development of plastics industry due, on one hand the emergence of many new polymers with very different characteristics, on the other hand improves their processing technologies. Injection and micro-injection with extruder, calendaring, are the main training techniques for plastics.Injection molding is the most popular method for producing plastic products because of its high productivity and the manufacturability for making various complex shapes also is a widely used, complex but highly efficient technique for producing a large variety of plastic products, particularly those with high production requirement, tight tolerance and complex shapes. The paper begins with an introduction on the evolution of obtaining and processing of plastics by injection and follow with injection and microinjection process presentation with issues such as: process scheme, injection stages, worms and mold displacement, plastification phases, comparison of conventional and modular mold development process. Following factors that influence the presentation, grouped into: input factors (process factors), factors related to material structure and machine and output factors. Also are presented and factors affecting precision molded parts. The main results from the literature refer to: standard deviation vs melt temperature, microgenetic algorithm for locate an optimal solution, weld line strength response to different gate size, weld line V notch profile and principle that the flow front shape influences the V notch; bubble size according to the residence time, microscopic images and roughness; creep strain at different mold temperatures, strategy for optimizing the cooling channels. Other part of the paper refers to analysis of injection and microinjection using different software. Thus for the beginning is presented the virtual reality environment for plastic injection molding. The main simulation are as follow: filling time, flow simulation, product ejection, gate positions, runner system, cooling channel position, cavity surface temperature profile, warpage and comparison of fibre orientation distribution. Specific properties of plastics products allow a high quality and high reliability to use in various industrial fields such as electronic engineering, aerospace and automotive industry, electrical industry, food industry, industry objects household etc.