mechanik-science.com MECHANIK 11/2019 How to cite this article: Authors: Wojciech Borkowski, Piotr Cichosz, Mateusz Pudłowski, Hubert Skowronek, Kamil Waszczuk Title of article: „ Influence of changes in machinability of nodular cast iron on manufacturing costs” Mechanik, No. 11 (2019) DOI: https://doi.org/10.17814/mechanik.2019.11.99 Influence of changes in machinability of nodular cast iron on manufacturing costs WOJCIECH BORKOWSKI PIOTR CICHOSZ MATEUSZ PUDŁOWSKI HUBERT SKOWRONEK KAMIL WASZCZUK* * * Mgr inż. Wojciech Borkowski, wojciech.borkowski@pwr.edu.pl, https://orcid.org/0000-0001-5906-0874 – Katedra Obrabiarek i Technologii Mechanicznych, Wydział Mechaniczny, Politechnika Wrocławska, Wrocław, Polska Prof. dr hab. inż. Piotr Cichosz, piotr.cichosz@pwr.edu.pl, https://orcid.org/0000-0002-1636-1973 – Katedra Obrabiarek i Technolo- gii Mechanicznych, Wydział Mechaniczny, Politechnika Wrocławska, Wrocław, Polska Mgr inż. Mateusz Pudłowski, mpudlowski@guehring.pl – Gühring Sp. z o.o., Dąbrowa Górnicza, Polska Dr inż. Hubert Skowronek, hubert.skowronek@pwr.edu.pl, https://orcid.org/0000-0003-3398-1661 – Katedra Obrabiarek i Techno- logii Mechanicznych, Wydział Mechaniczny, Politechnika Wrocławska, Wrocław, Polska, Dr inż. Kamil Waszczuk, kamil.waszczuk@pwr.edu.pl, https://orcid.org/0000-0002-7889-4847 – Katedra Obrabiarek i Technologii Mechanicznych, Wydział Mechaniczny, Politechnika Wrocławska, Wrocław, Polska Attempts to explain changes in the efficiency of nodular cast iron machining caused by the dispersion of its mechanical properties affecting on the intensity of tools wear (such as VHM drills) have been pre- sented. It has been also assessed to what extent changes in mechanical properties of tools, within the limits of the standards, can change the machining efficiency in quite intensive machining conditions of the automotive industry. KEYWORDS: machinability, nodular cast iron, drilling, costs Introduction Spheroidal cast iron has a very good strength and plastic properties. Moreover, it can be easily shaped by casting methods. Therefore, it is widely used in mass production, e.g. in the automotive industry. It is used to perform, among other: crankshafts, camshafts, connecting rods, steering system components or gears. One of the shortcomings of this material is bad machinability [1,6,7,9,10,13]. Material machinability has a crucial role in the products manufacturing. It affects not only the quality of manufactured elements, but - just as important - machining efficiency. A more detailed discussion of machin- ability is presented e.g. in publication [7]. In synthesis, it can be considered that the machinability depends on many factors, which include its physicochemical properties, including surface structure, type and machining method. Machinability is also closely related to: cutting properties of tool materials and protective coatings, blade geometry, including chip breaker, cutting support with cooling/heating and cutting zone lubrication, vi- bration cutting, trochoidal machining technologies, and also with technical condition and dynamic properties of the OUPN system. The main task of production is to make a product of the assumed quality, in the most efficient way, usually - as cheaply as possible or the most efficient, and occasionally in a way that is a combination of these demands. The same blank material, according to standard, even declared by the same manufacturer, as a result of changes in the blank manufacturing technology may be easier or more difficult to machining. The aim of this study was to present the impact of changes in the ductile cast iron properties on the drills durability and the machining efficiency in intensive mass production conditions. Workpiece During testing, they had used ductile cast iron (works norm [11]) corresponding to grade EN-GJS 500-7. Its chemical composition according to standard and from two blanks A and B deliveries are shown in the table.