GMT honeycomb panel is a composite of GMT and honeycomb core.
GMT means Glass-mat-thermoplastic. It is a composite of fiberglass mat and polypropylene film.
Base on the requirement of applications, Pentapur™ GMT honeycomb board can be as thin as 6 mm, to replace the traditional plywood which used for bus or coach luggage cabin or car trunk lid. The other thickness varies from 6-12mm, used as a bus sidewall, to replace plywood or CFRTP honeycomb panel where the cheap and more flexible surface is needed.
The GMT honeycomb is light, it can reduce the weight of a car boot floor by 20%.
The thermoplastic composite incorporates a sandwich panel made of polypropylene (PP) honeycomb and glass-mat thermoplastic (GMT) composite skin. The thermoplastic honeycomb is produced continuously while direct lamination of the sandwich skin layers can be integrated into the automated process in line.
These sandwich panels are suitable for trunk floor assemblies because they can deliver rigidity at low weight. However, given the high performance of the honeycomb structure, the use of material can be very limited.
Background information on GMT from Compositeworld are as below:
Once upon a time, glass-mat thermoplastic (GMT) composites were nearly the only option for engineers searching for increased stiffness, strength, and toughness in a polymeric material with a melt-reprocessable matrix, moderate costs, industrial-scale production capabilities, and relatively thin cross-sections. Filled and short fiber-reinforced thermoplastics, primarily nylon were limited to small, nonstructural parts that could be injection molded.
Developed by PPG Industries (Pittsburgh, Pa.) in the mid-1960s, GMTs offered molders, at a moderate cost, a compression moldable material with continuous random-fiber reinforcement. This material/process combination was conducive to industrial-scale production and fabrication of large parts with relatively thin cross-sections. Today there are two global GMT suppliers: Quadrant Plastic Composites AG (Lenzburg, Switzerland) and AZDEL Inc. (Forest, Va., a joint venture of PPG and GE Plastics, Pittsfield, Mass.) and a number of small, specialized producers, often selling in a single geography. For almost 30 years, GMTs faced little competition on the side of the thermoplastic of the composites arena, so their producers were able to focus efforts on converting applications previously produced in metals, fiberboard, and sheet molding compound (SMC). The technology, therefore, evolved relatively slowly.
Glass mat thermoplastics. GMTs are produced on huge laminators, using a thermoplastic resin and one or more forms of reinforcement. The process yields a lightweight, partially consolidated, semifinished composite in sheet form. Most forms are produced to 1,300 mm to 1,400 mm widths (about 52 inches to 55 inches). However, some newer forms are made to greater but proprietary widths. The sheet stock may be cut to size to suit placement in the tool for a specific application and also can incorporate a decorative or functional surface laminated to one side. GMT makes possible the production of large parts (up to 27.7 ft²/2.58m², with current press technology) with low tooling costs and fast cycle times via compression molding. The potential for parts consolidation presents the opportunity to further reduce weight and cost.
Early GMTs featured a polypropylene (PP) matrix with continuous/randomly oriented glass mat reinforcement. This material has high stiffness in all three axes and exceptional impact resistance, even at low temperatures (-40°C/-40°F), which otherwise would be the Achilles’ heel of glass-reinforced polypropylene. Early uses included compression-molded floor pans, seatbacks, battery boxes, bumper beams, and load floors for passenger vehicles as well as tractor components and military shipping containers.
There are many other applications for GMT honeycomb panel.