When the Boeing Research and Technology group of St. Louis works with Boeing suppliers to refine their machining processes, the researchers advise these shops to consider more than just the purchase price of the tool. A cheap tool can be expensive, if it limits the productivity of the machine. The article under "Editor's Pick" at right discusses the tradeoffs in more detail and provides equations to perform the analysis, but here are two links to handy tools. The calculators found here—one for roughing and one for finishing—can allow you to quickly determine how much a particular cutting tool actually costs in terms of dollars per unit of material removal. The tool cost, tool life and productivity are among the factors considered.