Engineering, 2016, 8, 79-85 Published Online March 2016 in SciRes. http://www.scirp.org/journal/eng http://dx.doi.org/10.4236/eng.2016.83010 How to cite this paper: Erameh, A.A., Raji, N.A., Durojaye, R.O. and Yussouff, A.A. (2016) Process Capability Analysis of a Centre Lathe Turning Process. Engineering, 8, 79-85. http://dx.doi.org/10.4236/eng.2016.83010 Process Capability Analysis of a Centre Lathe Turning Process Andrew A. Erameh 1 , Nurudeen A. Raji 2 , Rasheed O. Durojaye 3 , Abiodun A. Yussouff 4 1 Department of Mechanical Engineering, Igbinedion University, Okada, Nigeria 2 Department of Mechanical Engineering, Lagos State University, Ojo, Nigeria 3 Department of Structures and Aerodynamics, National Space Research and Development Agency, Lagos, Nigeria 4 Department of Computer Engineering, Grace Polytechnic, Omu, Nigeria Received 14 December 2015; accepted 12 March 2016; published 15 March 2016 Copyright © 2016 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract A process capability study is performed for the turning process on a general purpose center lathe in order to verify the process performance and machine ability to perform within specified toler- ance limit. The process and machine capability indices were measured to determine the process and machine adequacy for industrial application. The tolerance limits were obtained from the given nominal size of the shaft, using the basic hole system and 90 sample shafts were turned on the lathe machine to specification for varying spindle speed and feed rate of the lathe. Three (3) samples were randomly selected for the turning process of a combination of the spindle speed and feed rate as a subgroup size for a total subgroup of thirty (30). The diameters (representing the quality characteristics) were used to generate control charts and capability histogram for the process. The process is within statistical control but found incapable of meeting up to specification because the capability index (Cp) measured was less than 1 and the machine capability for indus- trial application is not adequate. Keywords Center Lathe, Specification, Control Chart, Range, Shaft, Basic Hole System, Process Capability, Turning Process 1. Introduction Machining is a general purpose manufacturing process for the manufacture of machine components and the per- formance evaluation of metal cutting machine tools is often based on their capability in machining work piece to specified details. The ISO standards had described the statistical methods of managing the machining process of