In modern times any product leaves the manufacturer without a previous machining. For this reason it is important to optimize the machining process by improving the mechanical behavior of the product. Enhanced machining properties of the used material ease the production process. This leads to the question, which factors have a positive impact on the machinability of the material. The main focus of this thesis is the influence of nonmetallic inclusions in a X38CrMoV5-1 hot working tool steel on its machinability. The first part of the work includes a detailed literature research with the topics steel cleanness, machining and machinability. Furthermore the effect of nonmetallic inclusions on the material properties and also on the machinability of the material is discussed. The second part of the work describes the operation of practical turning tests and automated SEM/EDS Analysis of three different X38CrMoV5-1 steel batches. The results of the machining tests lead to the understanding that the three various steel batches machined with changed cutting parameters and also different types of cutting inserts nearly show the same machined volume. In the same way, also the automated SEM/EDS Analysis only detects small differences in the inclusion landscape of the three steel batches. During this work a constant machinability of the X38CrMoV5-1 steel, regardless of the batch was determined. This special property of the steel grade on the one hand enables the improvement of current tools and the development of new tools on the other hand.