The machining process affects manufacturing cost, product quality and the environment. This paper presents a method for formulating a mathematical model for first estimating quality, cost and environmental 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 and the drilling quality estimation model through physical experimentation. Cost is estimated through an activity based costing approach. Environmental BOD and FOG impacts are estimated through stoichiometric analysis of cutting fluids. Inputs include material choice, feed rate, speed and cutting fluids. A case study of an automotive steering knuckle is presented.