Fundamentals of metal machining and machine tools/ Boothroyd

xiv, 350 hal.: bibl.: ill.: ind.; 21 cm

Estimating the costs of printed circuit assemblies

This article describes a method for estimating the assembly costs of printed circuit boards (PCBs). A worksheet is used which facilitates the recording of component insertion costs and costs associated with the assembly of mechanical items. For automatically-inserted components, these costs are summarized in a database. For manually-inserted components, a database of insertion and operation times is given. Manual insertion costs are then obtained by multiplying the times by a suitable manual labor rate. Data are also presented which will allow the costs of rework to be included in the analysis. The method has been implemented on a microcomputer and integrated with the Design for Assembly (DFA) software

An Extreme-Value Model of Concept Testing

We model concept testing in new product development as a search for the most profitable solution to a design problem. When allocating resources, developers must balance the cost of testing multiple designs against the potential profits that may result. We propose extreme-value theory as a mathematical abstraction of the concept-testing process. We investigate the trade-off between the benefits and costs of parallel concept testing and derive closed-form solutions for the case of profits that follow extreme-value distributions. We analyze the roles of the scale and tail-shape parameters of the profit distribution as well as the cost of testing in determining the optimal number of tests and total budget for the concept phase of NPD. Using an example, we illustrate how to estimate and interpret the scale and tail-shape parameters. We find that the impact of declining concept-testing costs on expected profits, the number of concepts tested, and total spending depend on the scale/cost ratio and tail-shape parameter of the profit distribution.Concept Testing, Prototyping, Extreme-Value Theory, New Product Development, Parallel Testing, Concept Selection, R...D Spending