General consequences of the packing phase in injection molding

The post‐filling phase in injection molding was analyzed via simple heat‐transfer and P‐v‐T models. An expression for the evolution of (volume‐averaged) pressure in a molding cavity during the cooling phase of the process was derived from the empirical Tait model combined with the transient heat‐conduction equation. This expression was used to establish general optimization criteria for the packing phase in injection molding, based on simple heuristics, and to assess the effects of various process and material parameters on the packing response of the system. The effects of gate geometry, part geometry, mold temperature, and melt temperature on the packing characteristics of a simple part are examined, and the general implications to the dimensional integrity of the part are discussed.