ENGEL's new machine separates waste plasticization and injection into two separate process steps in one machine.

During the on-site electronic seminar, injection molding machine and automation supplier Engel (Schwertberg, Austria) introduced a new two-stage process that accepts ground post-consumer waste as raw material and converts it into New molded parts, including thick-walled parts, do not require temporary granulation of waste. Eliminating this step not only saves time and money, but also reduces the thermal history of the recycled resin.

In a press release, Engel stated that the new machine decomposes plasticization and injection into two separate process steps, but they work closely with each other. In the first step, a conventional plasticizing screw is used to melt the raw material. In the second stage, the melt is transferred to the second screw for injection into the cavity. Alternatively, the plasticizing screw can be paired with a piston or plunger injection unit, allowing very large injections of up to 160 kg to be molded in a process that the company calls relatively low injection pressure.

Engel said that its new piston design eliminates some of the typical shortcomings that the injection device may encounter when changing materials. After rheology is optimized, the piston tip supports uniform flushing around the piston body, so as to achieve rapid changes in material and color. Starting from an injection weight of 20 kg, typical applications may include containers, trays and even large accessories.

The design of the process and the machine allows the molder to integrate a melt filter and degassing device on the injection side of the machine to ensure that the machine handles the devolatilized melt flow. An Engel spokesperson told Plastics Technology that the company can test its customers' materials and parts to ensure that the two-stage process can achieve the required upgrade quality.

In terms of overall throughput, the spokesperson said that the number depends on customer needs, including the required cycle time and raw materials. Based on these inputs, Engel selects the appropriate plasticizing screw diameter.

In terms of clamping force, the spokesperson stated that these machines are individually designed based on Engel's building blocks. Typical clamping forces start at 900 tons and can reach up to 4000 tons, but smaller clamping forces are also available. The injection unit and the plasticizing unit are arranged on top of each other to save space. Regarding the overall floor space, the spokesperson said that due to the optimized design of each machine component, the length of the machine has no effect compared with a standard injection unit with the same capacity. In fact, compared to a standard machine with the same injection capacity and injection weight, the piston injection variation actually has a smaller footprint.

Engel stated that the goal of its latest innovation is to allow the direct molding of post-consumer plastic flakes without the need to pelletize the waste first.

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