Modification of a vertical machining centre to include turning operations : an investigation

Abstract

There has been an accelerated use of Computer Numerical Control machine tools by developed countries over the past decade resulting in manufacturing companies becoming more competitive on the world market. However, the initial cost of these machines is prohibitive to many companies in the third world countries such as Zambia. Therefore,methods of adapting these machines to do much more than initially designed for would make the investment much more attractive. Various CNC machine builders have developed latest designs of combined turning and milling centres. This has been made possible through construction of more than three axes of rotation. None of the three-axis machining facilities convert a machining centre to a turning centre. It was the goal of this research to investigate the possibility of modifying a 3-axes CNC Vertical Machining Centre (VMC) to include CNC turning operations. This report outlines the research activity in the Department of Mechanical Engineering - School of Engineering at University of Zambia, exploring the methodology for widening the capability of a VMC to operate as a Turning Centre as well. The main objective was to add a modification to the existing Supermax 65A Vertical Machine Centre, so that turning operations could be performed within the designed parameters and programming software.During the research, fixtures for tool and workpiece holding were designed and produced.These were designed in line with the requirement for turning operations, original machine tool designed features and parameters. The use of Mastercam Mill software (Direct Numerical Control) and manual programming (Manual Data Input) were demonstrated as options for carrying out numerical control turning operations. Three samples of typical turned profiles were produced using designed fixtures. An estimation of force and power consumed during these operations was carried out. Although the study had certain limitations as regards the size and weight of turned jobs, it enhanced the number of part profiles that could be produced on the CNC Supermax 65A. The results proved that CNC machine tools could be improved for adaptability and productivity at minimum cost to a company.