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Compression Molding Compel® Long Fiber reinforced
Thermoplastics
Compel long fiber reinforced thermoplastics (LFRT) were designed
for production of composites by the plastication/compression process. Compel LFRT pellets are
one inch (25mm) long and contain reinforcing fibers of the same length. Even components with complex
geometry and deep ribs can be made with this material. In
compression molding, Compel LFRT has a number
of advantages over glass mat-reinforced thermoplastics (GMT):
- Unlimited design, without blank geometry constraints
- Low energy requirement due to screw plastication
- Low molding pressures required
- Very good melt flowability
- Constant glass fiber content even in thin ribs
- Good surface quality
- Recyclable production waste, given proper scrap granulation and
low
fines
- High toughness and stiffness
Process
The
Compel long fiber reinforced pellets are first prepared using gentle extrusion plastication. Screws
diameter should exceed 80mm (3.2 inches) and cross-section restrictions (such as in nozzles or diversions)
should be avoided to maintain the fiber length. Melting should be achieved without compression,
while keeping back pressure and screw speed as low as possible.
Next, the material is placed as a preplasticized mass into the
compression mold. The mold should be designed in accordance with typical compression molding practice
and tool temperature and cycle time should be as recommended for the specific material being processed.
The tool for ejecting the parts must be executed as a positive mold.
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