Involves combining the raw materials (fiber and matrix) immediately before entering the molder and avoids the production of an intermediate. This gives the manufacturer the ability to enhance the properties of the resin as required for the application by adding fillers, fire retardants and additives ,while also significantly reducing material costs and only establishing a single heat history of the matrix. This direct process can be separated into two process:
a) LFT-D-IMC (Long-fiber Thermoplastic Injection Molding Compounding Process)
Melts the polymer and mixes it with the fiber, is attached to an injection molding machine.
b) LFT-D-ECM (Long-fiber Thermoplastic Extruder Compression Molding)
Uses two extruders system for the polymer melting and fiber dosing coupled with hydraulic press for compression molding.
There are two primary advantages to LFT-D-ECM over the other two technologies.
First is that the compounding and fiber mixing steps are separated and therefore both extruders can be individually optimized for their specific functions.
Second, the material is not subjected to the same high levels of stress as in injection molding, which helps to maintain fiber length. This is critical because the mechanical properties of fiber reinforced thermoplastics are strongly dependent on the fiber length. Therefore, LFT-D-ECM process gives a maximum degree of freedom in terms of optimizing material choice, polymer modification, and process parameters, which is important for automotive applications.