Design and analysis of epoxy granite vertical machining centre base for improved static and dynamic characteristics

• Published in: Proceedings of the Institution of Mechanical Engineers. Part L, Journal of materials, design and applications Journal of materials, design and applications, 2020-03, Vol.234 (3), p.481-495
• Main Authors: Venugopal, Prabhu Raja, Dhanabal, P, Thyla, PR, Mohanraj, S, Nataraj, Mahendrakumar, Ramu, M, Sonawane, Harshad
• Format: Article
• Language: English
• Subjects: Cast iron; Configuration management; Damping; Dynamic characteristics; Finite element method; Granite; Machine tools; Machining centres; Milling (machining); Modal analysis; Modulus of elasticity; Resonant frequencies; Stiffness; Structural vibration; Surface finish; Vertical milling machines
• ISSN: 1464-4207; 2041-3076
• DOI: 10.1177/1464420719890892

The structural vibration in conventional machine tools which are generally made of cast iron may lead to poor surface finish of the machined components. This has led to the investigations on alternative materials for machine tool structures such as concrete, polymer concrete and epoxy granite which have higher damping properties but lesser Young's modulus. However, higher static stiffness with higher damping is essential for improving the static and dynamic characteristics of machine tool structures. Hence, this work focuses on replacing the vertical machining centre base made of cast iron with steel reinforced epoxy granite to improve the structural static stiffness. A finite element model of the above base is developed and validated against the experimental data obtained using modal analysis. The validated numerical approach is applied for investigating the seven progressive design configurations of base reinforced with steel. It is found that the epoxy granite base of Design configuration-7 with L-channels has significantly reduced the deformation by 56 and 36% considering milling and drilling operations, respectively, in comparison to cast iron base. Further, the natural frequencies of the above configuration are higher in all the modes (by more than 50%) under consideration than those of the existing cast iron structure. Therefore, the proposed configuration of base is a viable alternative for the existing base in order to achieve higher structural damping. The novelty of the present work is the design of epoxy granite vertical machining centre base using steel reinforcements to improve structural rigidity with ease of manufacturing.