Engel Austria is combining in situ polymerization of sold caprolactam and injection molding in a parallel process in a novel exhibit at Composites Europe 2016 in Düsseldorf, Germany, Nov. 29 to Dec.1. The result is net shape polyamide 6 composites made in a single step.
The exhibit will demonstrate a completely new reactive unit that can be combined with different types of injection molding machines. It’s an on-demand process that melts and process the solid monomer. Advantages include significantly reduced thermal load, and higher product quality.
Engel has developed a pre-series manufacturing cell in partnership with Schöfer, Schwertberg, Austria, which specializes in molds. The concept was first demonstrated in 2013, and was also shown at K2016. Shovels are produced on an Engel v duo 1560/700. The clamping unit is equipped with a sliding table fitted with two mold halves for easier accessibility.
Dry, pre-shaped reinforcing fabrics are inserted into the first cavity and infiltrated with the reactive matrix. Solid caprolactam is melted and metered in the reactive unit. Because the monomer has low viscosity in the molten state, the dry fibers can be easily wetted.
Because reactive processing takes place below the polymer’s melting temperature, the composite semi-finished product can be transferred to a second cavity immediately for injection molding with reinforcing ribs and contours of short glass fiber-reinforced PA 6. A viper 40 double robot handles the parts.
The technology will challenge resin transfer molding, which also makes composite parts from dry preforms in a single step. Target markets are automobile, teletronics and technical components.
Engel is putting significant focus on developing production systems for lightweight components. The composite manufacturing systems developed for aircraft component manufacturing are too slow for automotive and other high-volume markets.
The Center for Lightweight Composite Technologies established in 2012 by Engel in St. Valentin, Austria, is a testbed and skunk works for lightweight manufacturing. It’s now being expanded with a second (larger) v-duo 1700 machine with clamping force of 1,911 tons. The machine is equipped with a high-pressure metering system for reactive process technology, and may be combined with an IR oven.