Brief Introduction of 1. Materials
Glass Mat reinforced thermoplastic composite material (Glass Mat Reinforced Thermorplastic, referred to as GMT) is a thermoplastic resin as the matrix, glass fiber mat as the reinforced skeleton of the composite material, is currently the international active development of composite materials, is regarded as one of the new materials of the century. At present, it has attracted much attention in the automotive industry. GMT can be widely used in various parts of the car body, such as front-end parts, seat shells, engine noise shields, bumpers, instrument panel brackets and other components. It has the characteristics of novelty, energy saving, low density, low cost, high hardness, high strength, good toughness, impact resistance, corrosion resistance, waterproof, easy processing and forming, fast forming speed, long life, recyclable and light weight. I believe that in the near future, it will bring a new revolution to the entire automobile industry.
GMT is a late but rapid development. GMT can generally produce sheet semi-finished products, and then directly processed into the desired shape of the product. The molding process generally uses hot material cold mold molding process. The molding fiber may be a chopped glass fiber or a continuous glass fiber mat, and the thermoplastic resin may be a general-purpose plastic, an engineering plastic or a high-performance plastic. GMT has good mechanical properties, short molding cycle, low production cost, large and complex parts can be molded and has good dimensional stability. It is possible to reach the strength within the range of 50-300N/mm² by selecting GMT pre-cut according to the required size. The molded GMT parts are almost isotropic and have good strength for all types of impact, the product has no welds and is recyclable. It also has complex design functions, impact resistance, and easy assembly and reprocessing. It is expected to replace metal, plywood, wood and other parts in the future.
 

Advantages of 1. GMT materials
1, short molding cycle: molding products are diverse, compared with thermosetting sheet molding plastic SMC products, its production cycle is shorter, higher production efficiency, high-speed automated production, especially suitable for the production of large quantities of material products.
2. High strength: The strength of GMT is similar to that of hand-pasted polyester FRP products, and its density is 1.01-1.19 g/cm, which is smaller than thermosetting FRP (1.8-2.0 g/cm), so it has higher strength.
3, high rigidity: GMT contains GF fabric, even if there is a 10mph impact collision, can still maintain the shape.
4. Good impact performance: GMT has a 2.5-3 times higher impact absorption capacity than SMC. Under the impact force, SMC, steel and aluminum all have dents or cracks, while GMT is safe and sound.
5. Easy to integrate design: Many parts can be designed as a whole and become a single part with multiple functions, thereby greatly improving the production and assembly efficiency of parts.
6. Lightweight and energy saving: The weight of the car door made of GMT material can be reduced from 26Kg to 15Kg, and the thickness of the back can be reduced, so that the car space is large, and the energy consumption is only 60%-80% of steel products and 35%-50% of aluminum products.
7. Can be recycled: GMT waste and GMT old products can be re-produced after simple treatment, which not only improves the utilization efficiency of materials, but also reduces waste and avoids environmental pollution. Therefore, this material is called "green material". This is the outstanding advantage of GMT materials, which will help GMT materials occupy a broad material market in the future with increasingly stringent environmental requirements. In general, GMT can be recycled multiple times.
8. Light weight and good mechanical properties: The density of GMT material can be controlled at about 1.1, the tensile strength can reach 80MPa, the bending strength can reach 130MPa, and the impact resistance is good (the impact strength of notched cantilever beam can reach 650J/m).
9. The local damage of the product is easy to repair: After the local damage of the GMT material product, the damaged part and the resin of the repair material are melted by heating, and the repair can be repaired by cooling after heating.
10. Long storage cycle, etc.
In addition to this excellent performance, as an assembly component, the integrated characteristics of GMT material products determine its low system cost, and it is also very conducive to cultivating a supplier team with professional, mass production and modular supply capabilities. It will also greatly improve the management efficiency of the main engine factory to the supplier.
 

Application of 2. GMT Materials in Automotive Field
GMT sheet has high specific strength and can be made into lightweight parts. At the same time, it has high design freedom, strong collision energy absorption, good processing performance and short cycle. It has been widely used in the automobile industry abroad since the 1990 s. The market for GMT materials for the automotive industry will continue to grow steadily as fuel economy, recyclability and processability requirements continue to improve.
At present, GMT materials are widely used in the automotive industry, mainly including seat shells, bumpers, dashboards, engine hoods, battery brackets, pedals, fenders, etc.
1. For bus production: ceiling, route display board, engine compartment cover, battery box, window frame, driver's door, passenger door, radiator cover, fender, instrument panel, guardrail, front lamp holder, protective plate.
2. Used in truck production: cab, door, hood, buffer (bumper).
3. For the production of four-wheeled light vehicles: doors, hoods, front covers, radiator fan blades, door handles, front lamp holders, axle covers, and instrument panels.
4. Used in motorcycle production: motorcycle engine side plate, mudguard, motorcycle luggage rack, cooling fan, brake lever.
5. Used in train production: window frames, blinds, axle box covers, battery boxes, bathroom floors, roofs, bathroom sinks, distribution boxes, ceiling vents, fan blades, window sills, water storage tanks.





 

Application of 3. in other industries
In the construction industry, GMT can replace metal building formwork. This GMT template has the advantages of light weight, good peeling property, structural integration, smooth surface of the products, etc. In the transportation industry, GMT sheet is used as lining on the bottom plate of the container, which can greatly reduce the maintenance cost. In the packaging industry, it can be used for chemical storage, preparation of turnover boxes and containers. High-strength foam can also be used as sandwich to replace hardwood and metal containers. Other can also be applied to all-composite insulation ladder accessories, distribution boxes, pump covers, oilfield chassis base plates and bearing end covers, etc.

4. recycling
An important feature of the GMT material is its recyclability. It has been tested in cars on a mass production scale and has achieved good results. The method is generally as follows: the recovered GMT parts are heated and then molded into similar parts of the same quality or other types of parts, which can be repeatedly molded twice without significantly reducing performance, but if reused more than 4 times, the performance will be greatly reduced.
The recovered GMT is pulverized and made into a GMT powder or pellet. This pellet is very similar to standard injection plastic and can be used as a feedstock for injection molding machines or extruders. In the GMT manufacturing process, the GMT is made by replacing part of the PP and glass fiber mat with GMT powder or pellets. When the amount of recovered GMT material is less than 10% (mass fraction), it will not affect the processing performance and static and dynamic performance of GMT. When the recovery GMT is below 30% (mass fraction), it will not affect the performance of the matrix.