Injection moulding: processes and future challenges

Currently, fully electric machines use moulds built with optimized steels and alloys in order to achieve reduced cycle times and surface effects that are otherwise difficult to reach by means of other technologies. This combination of elements leads to very high production repeatability on a global scale and allow the production at low costs of plastic parts increasingly similar to alloys.

Injection moulding is a constantly evolving market where the search for high-performance raw materials has to face the pressure from government institutions to re-use plastic materials already present in the market. The major plastic converters are increasingly focusing on these issues as they need to meet the market needs as well as to maintain the sustainability of plastic materials already present in the market.
 

Mps takes part in this challenge: the latest generation production processes, a plant with a green vision, electric machines and water cooling systems adjust to the external temperature, thus optimizing the costs of transformation; particular care is taken in the choice of plasticization  and screw units to reduce the number of waste.

MPS uses several technologies, as listed below, to carry out injection processes:

• 1k moulding: traditional moulding process that consists in injecting only one type of plastic material  into the mould cavity;
• 2k moulding: moulding which involves the injection of two materials of different colors or of different morphological nature. Technologies are used with rotary tables, transfer or index plate;
• 3k moulding: moulding which involves the injection of three materials of different colours or of different morphological nature. Technologies are used with rotary tables, transfer or index plate;
• GID moulding: also called gas moulding or GIM. Pressurized nitrogen gas is injected into the interior of a mold. The gas flows through strategically placed gas channels to displace the material in the thick areas of the part by forming hollow sections. The result is obtained at reduced cycle times: hollow pieces that are  structurally performing. The material savings reach percentages up to 50 percent of the weight of the product;
• MuCell moulding: one of the latest technologies in the moulding sector, the MuCell process consists of injecting a gas (mainly nitrogen) in a super critical state directly into the cylinder during the plasticizing phase. In the following injection phase a physical expansion of the resin into low-pressure cavities is obtained. The expansion causes a reduction in the weight of the pieces and reduces their deformations. As a result, several advantages are obtained: a strong increase in dimensional stability, an almost total elimination of vacuum voids, a reduction in injection pressures and closing forces and appreciable reduction in cycle time and energy consumption. The new horizons opened by the use of MuCell technology and the advantages in terms of transformation, quality and global lightening of the component have given, in the last few years, a new and significant boost to this technology.
• Metal replacement moulding: the replacement of metallic materials (steels, aluminum alloys, cast iron ...) with high-performance polymeric materials is known as metal replacement. The recent developments of new and more performing thermoplastic materials allow to extend the applications to new products and sectors once exclusive of alloys. The manufactured articles made of thermoplastic material have similar performances to their metal equivalents and present strong benefits in terms of cost and productivity. Furthermore, high performance polymeric materials allow weight reduction, reduction in corrosive issue incidence, high wear resistance; noise and vibration reduction. At the same time it's possible to obtain a wide variety of colors and surface finishes.