The most common problem is poor surface appearance, specifically, glass fiber emergence on surface when manufacturing glass fiber reinforced Nylon.

The main cause is that glass fiber is physically mixed in Nylon matrix, but it will separate from matrix to certain extent after composite melts. The separation depends on a variety factors: glass fiber loading level and length, and material temperature. Because their poor flow in mold as compared to nylon, glass fibers in middle layers flow forward, but those in outside layers flow outwards to surface of mold, are blocked on the surface. Therefore, glass fibers are exposed on surface, so-called floating fiber.

The common solutions to fiber floating problem are materials, process and additives.

Solution one: Materials: select short glass fibers and Nylon resin with low viscosity.

Solution two: Process

1.   Appropriately increase screw shear;

2.   Increase injection speed, increase screw rpm to 70 – 90%;

3.   Increase injection pressure;

4.   Entire screw retracts 1-2 MM, preventing gate fiber floating;

5.   Apply to graded injection for some complex parts

Solution three: Additives

Add 0.3 - 0.6% silicone and 0.5 – 0.8% surfactants (disperse additives)