Early Cost Estimation of Injection Molded Components

David Archer, University of Rhode Island


The purpose of this study is the establishment of techniques that will enable product designers to quickly estimate the piece price and mold cost of an injection molded component at the concept design stage, before engineering drawings are generated. In using these techniques, the designer is made aware of the comparative costs of alternative design concepts, thus improving the product's cost-effectiveness and increasing the designer's awareness of the injection molding process. The capabilities of injection molding will briefly be compared to the capabilities of other processes with the intent of demonstrating when injection molding, and therefore the techniques derived in this study, may be applicable.

The methodology used to determine the three elements (material, processing, and tooling) of total manufactured cost concentrates heavily on input from molding and mold-making professionals. This is particularly true in the investigation of tooling costs.

The result of this research is a costing procedure that does not assume user knowledge of processing parameters or machine selection, but requires only designer-specified inputs, such as: part size, description of geometry, and material specified. Included is a comparison of the actual part cost and mold cost of 24 components loaned by local companies, with the costs predicted by the procedures developed in this project. To illustrate alternative choices of manufacturing processes for a given design problem, the total cost of a very simple component produced by three different methods, is plotted against plan area, life-cycle volume, and loading.