Modification of the Cavity of Plastic Injection Molds: A Brief Review of Materials and Influence on the Cooling Rates

Abstract

In the 21st century, a great percentage of the plastic industry production is associated with both injection molding and extrusion processes. Manufactured plastic components/parts are used in several industry sectors, where the automotive and aeronautic stand out. In the injection process cycle, the cooling step represents 60% to 80% of the total injection process time, and it is used to estimate the production capabilities and costs. Therefore, efforts have been focused on obtaining more efficient cooling systems, seeking the best relationship between the shape, the quantity, and the distribution of the cooling channels into the injection molds. Concomitantly, the surface coating of the mold cavity also assumes great importance as it can provide increased hardness and a more straightforward demolding process. These aspects contribute to the decrease of rejected parts due to surface defects. However, the effect of the coated cavity on the heat transfer and, consequently, on the time of the injection cycle is not often addressed. This paper reviews the effects of the materials and surface coatings of molds cavity on the filling and cooling of the injection molding cycle. It shows how the design of cooling channels affects the cooling rates and warpage for molded parts. It also addresses how the surface coating influence the mold filling patterns and mold cooling. This review shows, more specifically, the influence of the coating process on the cooling step of the injection cycle and, consequently, in the productivity of the process.

Innovative Injection Molding Process for the Fabrication of Woven Fabric Reinforced Thermoplastic Composites

“…Thermoplastic injection molding is influenced by several independent process parameters [53,54]. These process parameters, such as mold and melt temperature, injection and packing pressure, and packing and cooling time, affect the shrinkage and deformation of the final product [55,56]. Therefore, several studies have been conducted on the design of algorithms and multi-objective optimization models for the integration of injection molding process parameters [57,58].…”

Derivation of New Model for Injection Molding Cooling Time

“…Mold cooling time is the biggest contributor to the overall cycle time in almost all plastic molding applications (could be as high 70-80% of total cycle time). [6] Mold cooling analysis will helps optimize cooling layout, reduce cooling time, avoid hot spots, avoid filling/processing issues and most importantly save money [7] Fig 1 . Injection Cycle [8] Many research about cooling system in plastic injection mold geometry has been conducted. Experimental analysis Some researcher calculated cooling time by using empirical equation Omar A. Mohamed, S.H.…”