Analysis of Machining Time and Material Removal Performance as Factors Influencing Efficiency and Profitability

In the automotive industry, the machining of hardened surfaces has become a serious topic in terms of its manufacturing and economic efficiency in recent decades. The reasons for this are the machining difficulty of hardened components and the need for machining that results in increased accuracy and surface quality. In addition to grinding as the conventional fine finishing procedure substituting procedures such as hard turning have appeared. They can be applied to reach surface quality and accuracy values equal to those of grinding. This paper analyzes different machining procedures (conventional bore grinding, hard turning and combined procedure) on hardened internal cylindrical surfaces, compared them in terms of time parameters of machining and the practical material removal rate as an efficiency parameter of material removal. While the practical parameter of material removal rate allows efficiency-based comparison of identical or different procedures (machining with abrasive or single-point tools), while the time parameters of machining (mainly the operation time) aim at direct comparability of costs of the procedures. The cost-related relationships of the procedures are also analyzed.