Difficulty in machining calculated from mechanical and thermal properities of difficult-to-cut material

The paper deals with a difficulty in machinng that can be calculated from the mechanical and thermal properties of difficult-to-cut material. The calculated difficulty has good relation to the inverse of machinability rating (MR). To calculate that, a radar chart composed from four properties, hardness, tensile strength, elongation and thermal character, of a work material is used. The radar chart gives a feature of the work material, therefore, the rough strategy about machining can be estimated from the chart.