Meaning
Composite formulations combining polyamide 66 with embedded glass fibers provide high mechanical strength and thermal resistance. Structural automotive components under the hood often employ glass reinforced PA66 to withstand elevated temperatures. The addition of glass fibers raises the heat deflection temperature of the base polymer.
This enhancement allows the material to replace metals in challenging environments.
Anisotropic Shrinkage
Dimensional changes during cooling depend heavily on the direction of fiber alignment. With glass reinforced PA66, shrinkage parallel to the flow direction is much lower than shrinkage perpendicular to the flow. This difference leads to warpage in flat or thin-walled molded parts.
Designers use varying gate locations to distribute flow patterns and minimize internal stresses.
Fiber Orientation
Flow patterns in the mold cavity dictate the distribution of the reinforcement fibers. High injection speeds during the processing of glass reinforced PA66 push the fibers toward the walls, creating a distinct skin-core structure. Mechanical properties like flexural modulus are highest where the fibers align with the direction of applied stress.
Weld lines exhibit reduced strength because the fibers do not cross the weld interface. Flow simulations assist molders in positioning gates where high-strength fibers will align parallel to the direction of anticipated load.
Mold Wear
Abrasive materials accelerate the erosion of injection molding tooling. Processing glass reinforced PA66 requires hardened steel molds to withstand the abrasive action of the fibers. Gates suffer the highest wear rates due to high shear forces.
Regular tool maintenance is necessary to prevent dimensional drift in the molded parts.
