New processes overcome injection moulding challenges

The use of recycled plastic materials is growing worldwide as demand from consumers and political pressure to protect the environment mount. Various countries already stipulate the minimum recycled content for certain products. In the Western US, for example, some market applications require 25% recycled content for pails. In addition, many brands do not want the dark coloured recycled core material to be visible at the injection point. As a result, several injection moulding techniques are gaining ground, breaking away from traditional processes, to meet the sustainability goals.

At the ENGEL live e-symposium held in June this year, several new technologies were introduced highlighting process improvement in support of cost-saving recycling and increased use of recycled materials. Strengthening the use of recycled materials is one of the essential prerequisites for establishing a circular economy for plastics, which ENGEL is intensively promoting together with its partner companies.

A coinjection process that ENGEL has developed in cooperation with Top Grade Molds enables high and completely encapsulated recycled material content in the production of pails, and is thus superior to conventional processes for sandwich injection moulding. Another development is the two-stage process that makes it possible to process plastic waste as flakes in injection moulding directly after grinding, thus eliminating pelletising.

Very short cycle times, higher product quality

With a recycled material content of more than 30%, the 5-gallon pails produced during the ENGEL live e-symposium easily comply with the US specifications, which are very challenging as compared with other international standards. ENGEL’s development partner is Top Grade Molds from Mississauga, Canada, a mould manufacturer specialising in packaging applications. The pail mould for the world premiere is being provided by US pail manufacturer M&M Industries from Chattanooga, Tennessee. It is being deployed on an ENGEL duo speed injection moulding machine, which ENGEL developed specifically to meet the requirements of producers of pails and storage and transport containers. The large machine type combines productivity and efficiency with short cycle times. The coinjection process provides similar cycle times as producing pails in conventional single-component injection moulding.