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Cost and performance estimation are frequently used at the early stages of product development to determine the feasibility and drive critical design decisions. Early cost estimation has been hampered by the unavailability and uncertainty of information.

Here, cost estimates were derived from a complexity metric as defined by the number of dimensions that uniquely define the part geometry (2).

The cost drivers of manufacturing an injection molded plastic part Cpart are expressed in Eq. 1.1.

[1.1]

The material cost contribution, Cmat, is very significant, typically 50% to 80% of the total part cost. Tooling and processing costs are also significant cost drivers. The processing cost, Cproc, is dependent on the hourly rate charged for the usage of the injection molding machine as well as the processing yield, yproc, which is the ratio of good parts to the total number of parts produced. The tooling cost, Ctool, is amortized over the estimated production quantity N for the life of the tool.

Eq. 1.2 is an expression for the assembled product cost.

[1.2]

The m parts that constitute the product include both injection molded and standard purchased parts. The cost of the assembly is the product of the assembly shop hourly rate, Rassy, and the total time required to assemble the m parts constituting the product. Thus, the assembly cost decreases as part-count m decreases. The overhead cost per product COH includes both the shop and the administrative overheads.

Dimensionality and other critical design variables can be automatically assessed within modern computer-aided design systems throughout the product development process to provide continual feedback regarding tooling, process, and material costs (2).

The complexity-based models were developed and tested with empirical data for thirty injection molded parts from different suppliers and was found to have a highly significant correlation with mold costs and tooling lead times. Models for estimating material and processing costs and yield at the early stages of design are also developed. The developed methods enable real-time evaluation of the effects of a product design on its tooling cost, tooling lead time, processing costs, and yield at the early stages of design (2).