The thermal conditions like temperature distribution and heat fluxes during metal cutting have a major influence on the machinability, the tool life time, and the metallurgical structure of the work piece material. Though numerous analytical and experimental efforts have been developed in order to understand the thermal conditions in metal cutting, many questions still prevail. So, the exact form, distribution, and intensity of heat sources in the primary and secondary shear zone, which may describe the observed temperature distributions, are not explored to a satisfactory extend. On the other hand, the influence of the material properties like friction coefficient, heat conductivity, and shear strength is not yet fully understood. Another essential question is the heat flux partition among chip, work piece, and tool depending on process parameters and material. The particular novelty of the current investigation is a new methodological approach using modern thermal measurement system and postprocessing methods in order not only to measure the entire temperature field in the orthogonal cutting zone but also to calculate the affiliated heat flow distribution in the cutting process. Thus, the cutting process is treated as energy conversation process of the governing mechanical power into sensible heat. This point of view offers compatibility across process parameters and materials, thus new possibilities for process design.