ABSTRACT
These methods were also being used to process food which had solid particles imbedded in a viscous fluid. Hence it was natural to extend these manufacturing methods to process fiber suspensions as well. Fiber suspensions refer to chopped fibers suspended in a polymer melt. Compression molding involved placing the material containing fibers and resin in a solid form called the charge inside the mold cavity. Usually, the heat conduction mode is employed to heat the charge by direct contact with the mold platen to melt the polymer and create a suspension of fibers in the polymer melt. This suspension is compressed by the platen to occupy the mold and take the form of the mold cavity. After solidification, the part is removed from the mold. Unlike compression molding, which uses a mold platen to melt and displace the material, the extrusion and injection molding process use a screw to melt and move the material. The function of the screw in both these processes is similar to some extent during preparation of the suspension. Examples of screws used are shown in Figure 6.1.
