Machining Quality and Cost: Estimation and Tradeoffs

Abstract

Simultaneous improvement of machining cost, quality and environmental impact is sometimes possible, but after the Pareto optimal frontier has been reached, decisions must be made regarding unavoidable tradeoffs. This paper presents a method for formulating a mathematical model for first estimating quality, cost and cutting fluid wastewater treatment impacts of two machining operations (end milling and drilling), and then for tradeoff decision making. The milling quality estimation model is developed through virtual experimentation on a simulation model, while the drilling quality estimation model is developed through physical experimentation. Cost is estimated through an activity based costing approach. Cutting fluid wastewater treatment impacts (BOD and TSS) are estimated through stoichiometric analysis of cutting fluids. Input decision variables include material choice, design, manufacturing and limited lubrication parameters. The contribution of this paper is the integration of activity based cost estimation, machining quality estimation via statistical analysis of data from virtual and physical experiments, cutting fluid wastewater treatment impact estimation and formal decision theory. A case study of an automotive steering knuckle is presented, where decision variables include material choice (cast iron versus aluminum), feed rate, cutting speed and wet versus dry machining.