Meaning
Thermoplastic materials containing glass or carbon fibers that are typically less than one millimeter in length. Short fiber composites are the most common reinforced plastics used in injection moulding for structural applications.
Fiber Orientation
Molten plastic carrying the fibers flows through the tool, causing the reinforcement to align with the direction of the melt. This alignment makes the part much stronger in one direction than the other. Predicting this flow is essential for placing the gate in a location that maximizes the strength of the finished component.
Structural Performance
Adding fibers increases the stiffness and tensile strength of the base resin while reducing the rate of thermal expansion. These benefits come at the cost of reduced impact resistance and higher tool wear from the abrasive fibers. Designers must balance the need for rigidity with the potential for brittle failure under sudden loads.
Tooling Influence
Abrasive materials require hardened steel for the mould and the screw to prevent rapid erosion of the metal surfaces. Gates and runners must be designed to minimize fiber breakage and maintain the integrity of the reinforcement. High injection speeds can sometimes improve the surface finish but may also increase the risk of fiber-related defects.
