Injection molding packing time

In order to judge performance capabilities that exist within the controlled variabilities, there must be a reference to measure performance against. As an example, the injection mold cavity pressure profile is a parameter that is easily influenced by variations in the materials. Related to this parameter are four groups of variables that when put together influences the profile (1) melt viscosity and fill rate, (2) boost time, (3) pack and hold pressures, and (4) recovery of plastica-tor. TTius material variations may be directly related to the cavity pressure variation. Details on EQUIPMENT/PROCESSING VARIABLE are in Chapter 8. 

Desktop tools address design and manufacturing concerns such as gate placement, injection time/rate, injection pressure, melt and mold temperatures, packing time and pressure, cooling time requirements, and machine size requirements. 

Figure 10.9. Topical pressure profiles during injection molding. and stand respectively for nozzle and mold cavity pressure. Stages are 1 - dead time, 2 - filling, 3 - packing, 4 - cooling, 5 - ejection.

Undesirable adhesion to metal surfaces may cause a problem in injection molding, melt spinning, and thermoforming. In the melt spinning of PAS a variety of adhesion-related problems have been observed. These problems include the build up of polymer on spinneret surfaces resulting from both initial filament extrusion and lick-back from filament breaks. These adhesion-related problems lead to prematme spin pack failure and equipment down-time to replace spent spinneret packs, and can limit the use of PAS in certain melt spinning operations. 

Once the mold is filled and packed and the gate freezes off, the injection molding machine switches to the cooling stage. The amount of cooling is determined by the cooling time. While the melt in the mold cools to solid. 

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