GMT is a thermoplastic pre-preg, which offers better mechanical properties than injection molded reinforced thermoplastics due to the higher residual length of the glass strands. GMT is widely used in automotive applications such as underbody shields, seat structures, and front-ends. GMT is produced by consolidating a glass strand mat and a sheet of polypropylene. The glass mat is created by chopping assembled rovings and needling the mat. The intermediate product is delivered in the form of rigid sheets which are molded by the end user.
The GMT is transformed by heating the sheets. The pre-heated sheets are then molded by compression at a lower temperature. During the molding GMT flows inside the mold cavity, allowing complex features to be formed. GMT permits a high level of automation during blank cutting, pre-heating and introduction in the mold.