Part Details Review
Molten thermoplastic material is pushed into a mold during the injection molding process. With increased injection pressure the material flows farther. Increasing the melt temperature also achieves similar results due to the reduction in melt viscosity. Thin wall sections lose heat faster than thick sections, resulting in higher filling pressures in thin walled parts. Bayer MaterialScience has flow length information available for different wall thicknesses for its materials. Flow length is the distance from the gate to the farthest point the material can be pushed at the recommended melt temperature and injection pressure. Published flow length data is generated using molds with normal polished surface finish and adequate venting. Computer aided mold filling simulations help evaluate moldability of a part early on in the design stage, by predicting pressure losses and filling patterns, thus arriving at the appropriate wall thickness for optimum flow. Additionally, these simulations help resolve problems associated with flow hesitation, gas traps and even with improper gate location and weld line positioning. |