Engel Austria (Schwertberg; www.engelglobal.com) has developed a double flighted screw that is claimed to increase melting capacities and help avoid inadequate melt or part quality and possible wear on the barrel, screw and non-return valve in electric and hybrid injection moulding machines.

The screw has a flat cut feed zone that ensures a high input of shearing energy, guaranteeing that a high degree of melting has already occurred prior to compression. The company says this prevents the formation of a solid “wedge” that could result in deflection of the screw and increased wear. In addition, a second flight reduces deflection from the centre of the intake zone. This is situated directly opposite the first flight and brings a symmetrical pressure profile during plasticising.

In order to avoid feeding problems, the material is delivered initially through a single flight, achieving higher throughputs in comparison with a standard screw, particularly in difficult applications. These include technical articles made of PP, thin-walled technical articles made of PA and components made of POM. Depending on the plastic, average cycle time reductions of around 30% can be achieved with the same screw diameter, Engel said.