DIEFFENBACHER expands HP-RTM portfolio with pressure-controlled Ultra-RTM process

DIEFFENBACHER is expanding its HP-RTM (High-Pressure Resin Transfer Molding) portfolio with Ultra-RTM, a pressure-controlled process designed to protect the most delicate materials in composite manufacturing while maintaining cost-effective, reliable mass production. 

“Ultra-RTM offers our customers a highly precise, pressure-controlled advancement of the conventional resin injection process for composite parts,” explains Marco Hahn, Director Sales of the Forming Business Unit at DIEFFENBACHER. “Instead of relying on fixed press pressures or predefined pressure curves, Ultra-RTM uses pressure, position and temperature sensors integrated into the RTM mold to monitor cavity pressure online and in real time, enabling precise control that prevents part defects and protects tooling,” he adds.

The HP-RTM process is particularly suited for components with extremely high requirements regarding surface quality, strength and stiffness. Typically, HP-RTM requires high pressing forces because mold injection pressures can reach up to 140 bar. However, when processing pressure-sensitive core materials, such as low-density foam cores, honey combs or complex preforms, excessive pressure can damage these materials or distort the fiber architecture. The Ultra-RTM process eliminates this risk by operating at significantly lower cavity and injection pressures, both below 30 bar.

Ultra-RTM was developed by the Fraunhofer Institute for Chemical Technology ICT in Pfinztal, Germany, as an “RTM process variant for the cavity-pressure-controlled production of fiber composite structural components.” The process enables cavity pressure to be monitored, adjusted and limited through sensor technology and intelligent press control. Recognizing the benefits of this innovation, DIEFFENBACHER developed and implemented the corresponding hydraulic press control technology to turn the concept into a fully production-ready process.

The payoff is precision where it matters most. Thanks to active pressure control tailored to the specific process requirements, sensitive structures such as foam cores within sandwich constructions and complex preforms can be infiltrated reliably without collapsing or shifting. The targeted control strategy prevents sudden pressure peaks, minimizes void formation and ensures homogeneous fiber impregnation. The process is particularly suitable for lightweight construction applications in the automotive and aerospace industries.

“The advantages are obvious,” Hahn concludes. “Ultra-RTM reduces loads and simplifies the use and integration of sensitive core materials and complex preforms. At the same time, the innovative process enables manufacturers to produce high-performance, high-fiber-volume components using presses with comparatively lower pressing forces, resulting in reduced capital investment costs.”

Ultra-RTM already has a home on DIEFFENBACHER’s TailoredPress, which combines an economical monolithic press design with the latest intuitive DIEFFENBACHER EVORIS Control press control system and an energy-efficient drive concept. The press can be integrated into fully automated production environments at any time. In addition, DIEFFENBACHER’s digitalization solution, EVORIS Intelligence, which includes applications such as Anomaly Detection, Reports, and Energy Monitoring, can be seamlessly integrated into the press concept.