Mold fill direction

Fig. 6.8. Fracture toughness, K, of short glass fiber-thermoplastics injection molded composites as a function of weight fraction of fiber, fVr. (O) and (A) polyethylene terephthalate (PET) matrix ( ) and (A) polycarbonate (PC) matrix. Notches made transverse (O, ) and parallel (A, A) to the mold fill direction,...

Injection molded plaques or bars of PLC have a skin—core structure [33]. The molecular chains in the skin regions are largely aligned in the mold fill direction while the chain orientation in the core is more or less random. The high molecular alignment in the skin layer is induced by the elongational stress in the fountain flow and is immediately frozen upon contact with the mold surface. 

Stick/SoUd Retail Margarine. Two basic types of stick or solid packaging machinery are used in the United States (62). The first of these forms is a molded print that forces product into a measuring and molding chamber. The molded print is removed from the chamber and then wrapped and cartoned. On the second type of machine, the product from the resting tube is filled directly into a cell that is prelined with a preformed wrapper bag. The wrapping is then folded and ejected from the cell. 

The third "unit operation" process currently under study in RIM is the mold filling process (15). Measuring the pressure drop in the mold filling step allows the calculation of the viscosity. TVo cases exist that where viscosity is cans taint (little or no reaction) and the case where viscosity is a function of tenperature and conversion. The latter case requires a numerical solution to determine the viscosity. The type of information that can be gained from these studies is directly relatable to how well a material will RIM process in a tool -again this type of information should aid in tool design. 

The advantage of ASTM D3123 is that it is simple to perform and provides direct evidence of the mold-filling capability of the polymer. The dis-... 

Farther toward the center of the mold, the shear stress gradually decreases and becomes too weak to break down the domains to induce large-scale orientation in the filling direction. The melt experiences a tumbling flow of domains. This is the formation of the intermediate... 

Figure 1 Two types of weldlines in injection-molded parts (mold-filling patterns in double-gated rectangular cavities), (a) Melt fronts flowing in opposite directions. (b) Mold with two gates side by side. Weldlines are indicated by dashed lines.

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