This updated molding system allows you to continuously use a single mixing head on multiple HP-RTM molds without losing in-mold pressure.
April 9, 2019
This patented pressure-locking system enables a single mixing head and press to serve multiple HP-RTM or foam molds in sequence, reducing equipment requirements while maintaining stable in-mold pressure and process control.
Holding tight under high pressure
One challenge for HP-RTM is needing to keep the injection head connected to the mold until polymerization is complete. Traditionally, the head could not be removed from the injection port when the shot was finished because doing so would cause the pressure inside the cavity to drop, compromising the curing process.
We have developed a method, engineered in multiple configurations, that allows a single mixing head to be used continuously across multiple HP-RTM molds.
The system is designed to maintain the pressure built up inside the mold after injection by sealing the cavity with a mechanical device that separates the area containing the molded part from the injection sprue. This pressure-tight separation allows the mixing head to be removed immediately after injection and made available for rapid sequential use on other molds, without compromising in-mold pressure.
The method simplifies plant design by reducing the amount of piping and the number of valves and mixing heads required, resulting in clear advantages for cost and maintenance.
One solution for two technologies
Our solution is designed for two different applications: compact HP-RTM composites, including CFRP and GFRP, and expanded polyurethane (PUR) foams.
The patented system can withstand a pressure differential of up to 100 bar and operating temperatures of up to 150°C, making it suitable for demanding HP-RTM processes.
For one major European composites manufacturer, the solution significantly reduced the investment required for a complete production line. Instead of four mixing heads and four polymerization presses, the manufacturer now requires only one mixing head and one polymerization press.
The mold, equipped with a pressure-locking device, is mechanically sealed and can be removed from the injection press as soon as the liquid-to-solid reaction begins. The pressure profile inside the locked mold remains unchanged throughout the process.
For expanded foam applications, the system can also be used with multi-cavity molds. A similar locking device allows individual cavities to be filled sequentially, enabling different parts to be produced using the same mold while maintaining precise density control.
