EconCore & MEAF Collaborate on Advanced Continuous Thermoplastic Honeycomb Cores

EconCore (Leuven, Belgium) is making progress in development of new all-thermoplastics continuous honeycomb cores. The advances come after the installation of a laboratory-scale extrusion and forming line at the company’s R&D facilities in Leuven, Belgium.

At the heart of the line is a purpose-built 50-mm extruder, built by MEAF (Yerseke, The Netherlands), and equipped with a special 500-mm sheet die built by flat-die specialist EMO Extrusion Molding (Micheldorf, Austria).

EconCore honeycomb structures are produced from a single continuous thermoplastic sheet using the company’s patented ThermHex technology. This involves a sequence of thermoforming, folding and bonding operations. Cell size, density and thickness of the honeycombs can be altered with simple hardware and/or process parameter adjustments. The process allows for inline bonding of solid skins to one or both sides of the honeycomb, to create a cost-effective finished composite panel.

Prior to the installation of the new purpose-built extruder, EconCore was carrying out its honeycomb developments using sheet unwound from a roll. “Now that we can produce our own sheet in-line, we have more flexibility in our operations and it is obviously much easier to make changes to the material formulations,” says Wouter Winant, the company’s Technical Manager.

EconCore and MEAF collaborated closely on the design of the laboratory extruder, which is also capable of processing polyolefins, bioplastics and high-performance thermoplastics such as polycarbonates, polyamides, and polyphenylene sulphide.

Winant says, “This is a nontypical set-up, but it is very important for our development work. EconCore already has licensees around the world producing continuous honeycombs and honeycomb-cored laminates in polyolefins — predominantly polypropylene — and we intend to continue refining the process technology for these materials. The new line is partly intended for this purpose. At the same time though, we are extending the potential of ThermHex technology by enabling it to be used with thermoplastics with superior mechanical and thermal performance — what we call HPTs. Normally this would require the use of a second extruder, since the processing characteristics of polyolefins are quite different from those of HPTs. But with this purpose-designed extruder, we have so far managed to obtain excellent results on around 10 different kinds of polymers.”

The MEAF extruder has a 50-mm barrel holding a screw with an L:D of 34:1, which is typical for polyolefins. However, it also has good heating capability, with each of its five zones rated at 5.8 kW. Despite its high power rating, the extruder is highly energy-efficient. A 600-L dryer for hygroscopic materials is integrated into the production system. Maximum output from the extruder is around 150 kg/h.