Machinability of rectangular bars of nodular cast iron produced by continuous casting
- 41 Downloads
Continuous bars of ductile iron are widely used for parts produced by machining processes, for example, hydraulic manifolds, hydraulic cylinder pistons, bushings, and pump housings. The main reasons for the selection of ductile iron bars are the high strength, stiffness, toughness, wear resistance, cost, and machinability. Concerning this last property, the best machinability is obtained for a ductile iron with a predominantly soft ferritic matrix. The rate of the solid-state transformation of austenite into ferrite, the so called “stable eutectoid reaction,” is dependent on the diffusion distance from the austenite to graphite particles, in other words, on the maximum distance between the graphite particles. If this distance increases, the time for the reaction may not be sufficient, and a “metastable eutectoid reaction” can occur, with the decomposition of austenite into pearlite, a mixture of soft ferrite with iron carbide. This constituent, called pearlite, shows higher hardness than ferrite, and so it must be machined under different conditions compared with a ferrite matrix. Thus, the distance between the graphite particles, measured by the number of graphite particles per unit area, determines the type of ductile iron matrix. The number of graphite particles is governed mainly by the solidification speed. In the continuous casting of bars of ductile iron, there is a variation in the solidification speed from the surface of the bar to the center of the section, decreasing toward the center. This is particularly important in thick sections, where the difference in the solidification speed is significant, leading to a variation in the microstructure from the surface to the center. This variation in the microstructure was the focus of this study, measuring various parameters connected to machinability, such as torque, power consumption, tool life (with tool wear analysis), and surface roughness. The goal was to show that the machining conditions must be changed when machining different positions on the section of a thick continuous ductile iron bar. Lower torque and shorter tool life were obtained when cutting the core in relation to the periphery region. However, in terms of power consumption and surface roughness, there was no statistical difference between the regions evaluated during the milling process. The variability of the machining output parameters is related to the mechanical properties along the cross section of the bars.
KeywordsMachinability Nodular cast iron Continuous casting Milling process Tool wear Surface roughness
Unable to display preview. Download preview PDF.
The authors are grateful to Tupy S.A. for providing the work materials to carry out this project. One of the authors received a scholarship to carried out this research, which was provided by CAPES (under project number 002659/2015-08 PDS).
The authors are grateful to CNPq, FAPEMIG, and CAPES for the financial support.
- 1.Petry, C. C. M., 1999, Avaliação das propriedades de impacto e dos mecanismos de fratura de Ferros fundidos nodulares ferríticos [evaluation of impact properties and fracture mechanics of ferritic nodular cast irons], Dissertação de Mestrado [Master’s dissertation], Universidade Federal do Rio Grande do Sul, Porto Alegre/RS, Brasil. In PortugueseGoogle Scholar
- 3.Barbosa PA, Costa ES, Guesser WL, Machado AR (2015) Comparative study of the machinability of austempered and pearlitic ductile irons in drilling process. Journal of The Brazilian Society of Mechanical Science and Engineering – JBSMSE, São Paulo – SP – Brazil 37:115–122. https://doi.org/10.1007/s40430-014-0161-z CrossRefGoogle Scholar
- 4.Wilk-Kolodziejczyk D, Regulski K, Gumienny G (2016) Comparative analysis of the properties of the nodular cast iron with carbides and the austempered ductile iron with use of the machine learning and the support vector machine. Int J Adv Manuf Technol 87:1077–1093. https://doi.org/10.1007/s00170-016-8510-y CrossRefGoogle Scholar
- 5.Dawson S, Schroeder T (2004) Practical applications for compacted graphite iron. In: AFS transactions, American foundry society. Des Plaines, USAGoogle Scholar
- 7.Guesser WL (2009) Propriedades mecânicas dos ferros fundidos [Mechanical Properties of cast irons]. Editora Edgard Blucher, São Paulo – SP 1:309 In Portuguese Google Scholar
- 8.Feres F (2011) Ferro fundido nodular pode substituir o aço – Tendências e oportunidades [Ductile iron can replace steels – Trends and opportunities]. O mundo da Usinagem, São Paulo/SP, Brasil, vol 6:35–36 In Portuguese Google Scholar
- 10.Nayyar V, Kaminski J, Kinnander A, Nyborg L (2012) An experimental investigation of machinability of graphitic cast iron grades; flake, compacted and spheroidal graphite iron in continuous machining operations. Procedia CIRP 1:488–493. https://doi.org/10.1016/j.procir.2012.04.087 CrossRefGoogle Scholar
- 15.PN-EN 1563:2000, Polish and European Standard - PES (2000). Nodular iron. ClassificationGoogle Scholar
- 16.Martinez I, Tanaka R, Yamane Y, Sekiya K, Yamada K, Ishihara T, Furuya S (2017) Wear mechanism of coated tools in the turning of ductile cast iron having wide range of tensile strength. Precis Eng 47:46–53. https://doi.org/10.1016/j.precisioneng.2016.07.003 CrossRefGoogle Scholar
- 18.De Sousa JAG, Machado AR, Da Silva RB, Guesser WL (2017) Study of the variability of the machinability along the cross section of ductile iron produced by continuous casting. Procedia Manufacturing 10:307–318. (Proceedings of the 45th SME North American Manufacturing Research Conference, NAMRC 45, LA, USA. https://doi.org/10.1016/j.promfg.2017.07.062 CrossRefGoogle Scholar
- 19.Suarez, M. P., 2008, Fresamento de canais da liga de alumínio aeronáutico 7075-T7 [Slot milling of aeroespace aluminum 7075-T7], Dissertação de Mestrado [Master dissertation] do Programa de Pós-Graduação em Eng. Mecânica, Universidade Federal de Uberlândia, Uberlândia/MG, Brasil, 149 p. In PortugueseGoogle Scholar
- 20.Sandvik Coromant, 1994, Modern metal cutting, a practical handbook, Sandvik Coromant, technical editorial dept. AB Sandvik Coromant, S-81181 Sandviken, SwedenGoogle Scholar
- 22.Bowen M (1984) The welding of ductile irons. Foundryman, p:303–312Google Scholar
- 24.Trent EM, Wrigth PK (2000) Metal cutting. Butterworts, England 4:446Google Scholar
- 25.Xia, Y., Liu, W., Xue, Q., 2002, Friction and wear behaviour of nodular cast iron modified by a laser micro-precision treatment sliding against steel under the lubrication of liquid paraffin containing various additives, Wear, v 253, n. 7–8, p 752–758Google Scholar
- 26.Stoeterau, R. L, 2012, Processos de Usinagem [Machining Processes], Available at: http://www.lmp.ufsc.br/disciplinas/emc5240/Aula-10-U-2007-1-Forcas.pdf, − accessed on September 14th 2012. In Portuguese
- 27.Machado, A. R., Abrão, A. M., Coelho, R. T., Da Silva, M. B., 2015, Teoria da usinagem dos materiais [theory of materials machining], Editora Edgar blucher, São Paulo – SP, 407 p. [In Portuguese] Google Scholar
- 28.Santos, S.C. and Sales, W.F., 2007, Aspectos tribológicos da usinagem dos materiais [Tribological aspects of materials machining], Ed. Artliber, São Paulo, SP, Brasil. In PortugueseGoogle Scholar