Final adjustments and modifications are done in-house, with special attention given to manufacturability and critical dimensional requirements. The tool builder is given the tool design specifications for mold construction. Once these are reviewed and approved, the detailed design is finalized. Preliminary 2D and 3D design models are constructed to determine mold sides and steel sizes. A comprehensive process failure mode effects analysis (PFMEA) is also completed. Tooling specifications and tooling sources are finalized and purchased component sources qualified. Manufacturability review includes confirmation of standard plastic design practices and incorporation of tooling details to create the most robust design possible. Mold flow evaluation is also undertaken to determine the best type of gate and gate locations, in addition to determining proper vent locations. The physical and chemical properties of the selected resin are also evaluated so that the proper mold steel can be selected and mold cooling be reviewed. The team especially looks for any potential problems in part geometry or tolerance that might result in poor steel conditions or require special tooling features such as lifters, slides, and threading/unthreading. In this initial stage, design engineers, tooling engineers, materials engineers, manufacturing engineers, quality engineers, and lab technicians work together to determine product specifications, mold component functionality, mold materials, operational constraints, and any needed product enhancements and improvements. Stage 1: Manufacturability and Feasibility There are other components that can be added to a mold to form complex geometry rotating devices (using mechanical racks and gears), rotational hydraulic motors, hydraulic cylinders, floating plates, and multi-form slides are just some examples. These often must deal with features such as undercuts or threads, which typically require more mold components. In general, more complex injection-molded products require more complex molds. Uneven cooling may result in defects called “hot spots”-areas of weakness that affect repeatability. Proper placement of cooling channels in mold walls to circulate water are also essential for cooling to create a final product with homogeneous physical properties, resulting in repeatable product dimensions. The system of runners and gates must be carefully designed to assure even distribution of plastic and subsequent cooling. The direction of flow is controlled by the “gate” at the end of each channel.

Tooling engineers also need to calculate gate/runner sizing specifications for proper filling and minimal cycle times, as well as determining the best shut-off methods for tooling durability over the life of the program.ĭuring the injection molding process molten plastic flows through channels called “runners” into the mold cavity. Waterlines must be well-placed to maximize cooling and minimize warping. Steel hardness must also be determined to maintain the proper balance between wear and toughness. For example, the proper grade of steel must be selected so components that run together do not wear out prematurely. Depending on production needs, “multi-cavity” molds can be designed to create multiple identical parts (as many as 100 or more) during the same run.ĭesigning the mold and its various components (referred to as tooling) represents a highly technical and often complex process that requires high precision and scientific know-how to produce top-quality parts with tight dimensions. The space that these two parts create when the mold is closed is called the part cavity (the void that receives the molten plastic). The injection mold consists of two parts: the mold core and the mold cavity. The piece is then ejected from the mold, either as the final product or as a near-final product that is sent on for secondary finishing. Injection molding is a high-precision manufacturing process that injects molten plastic into a carefully designed mold, where the plastic cools and hardens into the specified part or product.

Metal injection