A contribution to the study of alloy 625 turning

Orientador: Anselmo Eduardo DinizDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: As indústrias automotivas, aeroespaciais e de energia vêm testemunhando uma maior procura por materiais para fabricação de componentes críticos, tais como ligas à base de titânio e à base de níquel, principalmente devido à alta relação resistência mecânica/peso e à capacidade de manter propriedades mecânicas em temperaturas elevadas e em ambientes corrosivos. Isto gerou a necessidade de se criarem modos economicamente viáveis para fabricar componentes que têm estas ligas por base. Ligas à base de níquel são consideradas muito difíceis de usinar quando comparadas ao aço com as mesmas propriedades em temperatura ambiente, pois elas, dentre outras propriedades, mantêm a resistência mecânica em elevadas temperaturas. Neste trabalho, foram testadas alternativas para elevar o desempenho das ferramentas durante a o torneamento de Inconel 625, quais sejam: estratégia de corte cônico e refrigeração com alta pressão. Os resultados indicam que a estratégia de corte cônico não é indicada por produzir vida de ferramenta semelhante a do corte longitudinal (com desvantagem de dobrar o número de passes) e indicam também que a utilização da refrigeração com alta pressão é interessante, pois favorece a redução de temperatura e consequente aumento da vida da ferramenta e também a afasta o cavaco gerado da região de corte. Assim, a adoção de sistemas de refrigeração com alta pressão é um procedimento adequado para a usinagem de InconelAbstract: The automotive, aerospace and power industries have witnessed an increased demand for materials for manufacturing critical components, such as titanium alloys and nickel-based alloys, mainly due to high relative strength/weight and the ability to maintain mechanical properties at high temperatures and in corrosive environments. This has generated the need to establish economically viable ways to manufacture these components. Nickel-based alloys are considered very difficult to machine when compared to steels with the same properties at room temperature, since they, among other properties, maintain mechanical strength at high temperatures. In this paper, alternatives were tested to raise the performance of the tools for the turning of Inconel 625: taper turning strategy and cooling with high pressure. The results indicate that the tapered cutting strategy is not suitable, once tool life was similar to the longitudinal cutting (with the disadvantage of doubling the number of passes), and also indicate the advantage of using the refrigerant at high pressure due to temperature reduction and consequent increase in tool life and removal of chips generated from cutting region. Thus, the adoption of refrigeration systems with high pressure is a suitable procedure for machining InconelMestradoMateriais e Processos de FabricaçãoMestre em Engenharia Mecânic

Effect of the relative position of the face milling tooltowards the workpiece on machined surfaceroughness and milling dynamics

In face milling one of the most important parameters of the process quality is the roughness of the machined surface. In many articles, the influence of cutting regimes on the roughness and cutting forces of face milling is considered. However, during flat face milling with the milling width B lower than the cutter's diameter D, the influence of such an important parameter as the relative position of the face mill towards the workpiece and the milling kinematics (Up or Down milling) on the cutting force components and the roughness of the machined surface has not been sufficiently studied. At the same time, the values of the cutting force components can vary significantly depending on the relative position of the face mill towards the workpiece, and thus have a different effect on the power expended on the milling process. Having studied this influence, it is possible to formulate useful recommendations for a technologist who creates a technological process using face milling operations. It is possible to choose such a relative position of the face mill and workpiece that will provide the smallest value of the surface roughness obtained by face milling. This paper shows the influence of the relative position of the face mill towards the workpiece and milling kinematics on the components of the cutting forces, the acceleration of the machine spindle in the process of face milling (considering the rotation of the mill for a full revolution), and on the surface roughness obtained by face milling. Practical recommendations on the assignment of the relative position of the face mill towards the workpiece and the milling kinematics are given95sem informaçãosem informaçã

Evaluating the use of high-pressure coolant in turning process of Inconel 625 nickel-based alloy

The automotive, aerospace and energy industries have lately increased their search for materials which must have high mechanical resistance/weight ratio and capability to maintain the mechanical properties in high temperatures and at corrosive environments in order to produce critical parts of their equipment. The nickel-based alloys are one type of materials which have been a good answer for this search. On the other hand, the very good mechanical properties of these alloys make their manufacturing very difficult, especially when machining processes are used. Among other problems in the machining of these alloys, due to the high mechanical resistance in high temperature, tool lives used to be much shorter than when steel alloys are machined, forcing cutting speeds to be much lower and, consequently, to have less productive processes. The main goal of this work was to test an alternative to increase tool life in the turning of Inconel 625 nickel-based alloy by the use of high-pressure coolant. This system was tested using different directions of the fluid flow (toward the rake face, toward the flank face and directing the fluid simultaneously toward these two tool faces) compared to the conventional way of applying fluid. The results show that the use of high-pressure coolant harms the notch wear development and, consequently, increases tool life with simultaneous improvement of workpiece surface roughness in some cases. However, the application of high-pressure coolant over both flank and rake faces at the same time did not provide any improvement23271182119

Reduction of internal turning surface roughness by using particle damping aided by airflow

In internal turning of hardened steel carried out with cubic boron nitride (CBN) tools, the main concern is with the workpiece surface finishing, usually aiming to achieve a surface roughness similar to the attained in grinding processes along with gains in productivity. However, vibrations from the process often cause premature chipping in the tool and/or damage to the workpiece finishing. To minimize vibration, one solution is the use of passive and active dampers with different types of construction. Passive damper contrasts with active damper due to its low cost and simpler construction. The use of particle impact passive damper aided by compressed air to promote workpiece surface roughness reduction was studied. For this, different materials, particle size, packing ratio, and overhang boring bar were tested. Based on the results, it was possible to conclude that the airflow aided particle damper reduced the mean surface roughness by around 60% compared to non-airflow damping in 120 mm (L/D = 6) boring bar overhang106125131sem informaçãosem informaçã

Effect of the Relative Position of the Face Milling Tool towards the Workpiece on Machined Surface Roughness and Milling Dynamics

In face milling one of the most important parameters of the process quality is the roughness of the machined surface. In many articles, the influence of cutting regimes on the roughness and cutting forces of face milling is considered. However, during flat face milling with the milling width B lower than the cutter’s diameter D, the influence of such an important parameter as the relative position of the face mill towards the workpiece and the milling kinematics (Up or Down milling) on the cutting force components and the roughness of the machined surface has not been sufficiently studied. At the same time, the values of the cutting force components can vary significantly depending on the relative position of the face mill towards the workpiece, and thus have a different effect on the power expended on the milling process. Having studied this influence, it is possible to formulate useful recommendations for a technologist who creates a technological process using face milling operations. It is possible to choose such a relative position of the face mill and workpiece that will provide the smallest value of the surface roughness obtained by face milling. This paper shows the influence of the relative position of the face mill towards the workpiece and milling kinematics on the components of the cutting forces, the acceleration of the machine spindle in the process of face milling (considering the rotation of the mill for a full revolution), and on the surface roughness obtained by face milling. Practical recommendations on the assignment of the relative position of the face mill towards the workpiece and the milling kinematics are given