Corebon induction heating

Corebon (Malmo, Sweden) provides production solutions for manufacturing and assembly of fiber-reinforced composites using thermoset and thermoplastic polymers, including high-end aerospace materials. “Our solutions are based on proprietary induction technology that uses highly efficient noncontact heating,” says Kenneth Frogner, head of R&I at Corebon. “This provides unique opportunities for molding composite parts.”

Induction can be used to heat all types of electrically conductive materials, he explains, including steel, Invar, aluminum and carbon fiber. “Induction has been used for about a century to heat small metal objects, but large parts and complex geometries have, with some exceptions, been a challenge until recently,” explains Frogner. “By providing very uniform heating and cooling, Corebon can help reduce the mass of the molds to a minimum, limited only by the structural requirements and to resist pressure during molding. This enables fast and efficient temperature cycling of metal molds.”

“While traditional induction heating suffers from size and geometrical limitations,” he continues, “with significant losses in the coils, Corebon uses flexible wires and modern materials, resulting in superior energy efficiency versus other heating methods. For example, 90-95% of the power in the wall outlet is transformed into heat within the mold. We can typically reduce energy use by 50-80% compared to traditional composites processes. However, the largest energy savings come from the reduction in the mold’s thermal mass.”

Corebon provides different types of tooling solutions, including metal shell tools with or without support structure (see CW’s reporting on “Tooling for composites,” Weber’s NVD tools and a nickel shell tool at Dowty Propellers). “We can also accommodate tools with a significant thickness variation,” says Frogner. “Shell tools are the most efficient, with possible heating and cooling rates of more than 100°C/minute, and they are the best suited for volume production. Similar to how each part needs a custom-made tool, each induction-heated shell tool needs a customized inductor and cooling configuration. Cooling uses air, water or a mixture, depending on the application requirements.”

For tools with a flat back side, Corebon offers more generic solutions that can be used with different tool geometries. These CorePlates are available in three formats depending on the heating and cooling technology used:

• All-in-one is a thermally cycled plate, typically mounted in a press, where heating and cooling are transferred to the mold through the lightweight press platens.
• Adapt plates enable the molds to be directly heated by induction with two different options for cooling: within the mold or through conduction from a cooling structure.
• Tailor is a combination of the other two, tailored for a certain geometry, where faster heating and cooling rates can be achieved. This approach is used when a high level of optimization and high production rates are needed, for applications with only minor geometrical variations.

Alia Mentis used a CorePlate Adapt tool, modified to its design, for the CFRP car hood to demonstrate its Koridion active core molding process (see “Active core molding: A new way to make composite parts.”).

The heart of Corebon’s induction technology is its frequency inverter, says Frogner, which powers the heating and enables sophisticated process control. “Our inverters have been developed specifically for use with composites,” he explains. “They are easy to operate and offer a wide range of functionality, making them versatile. For example, our systems can be used for induction welding or easily integrated into autoclaves or press systems.”

The CorePower inverters are modular and can be stacked for larger production setups. They can also supply power to multiple zones to maintain very uniform temperature across changes in thickness and geometry. “We also have features that enable real-time analysis of process data for improved process control,” says Frogner.

He notes that Corebon is also working with direct heating of carbon fiber structures. “Induction welding of carbon fiber thermoplastics is one example, but we are also providing in-situ heating for preforming of prepreg and dry layups.”

“Our goal is to remove the limits that hold composites manufacturing back,” says Frogner. “So, we are very aligned with Alia Mentis and their Koridion technology. Corebon as a partner offers very fast, accurate heating and cooling, resulting in shorter cycles using less energy.”