Development of a Computer Aided Process Planning System for Parts Machining by Means of a Sliding Headstock Automatic Lathe

Sliding headstock automatic lathes allow a workpiece to move in Z-axis while a tool remains stationary to machine tiny parts in a short cycle time. They have usually two turning spindles opposing each other with plural turrets and deliver the workpiece between the spindles sequentially in front and back parallel machining. However, with the changes in the production of small quantities of many types of parts, the preparation for a machining process occupies a high ratio of production lead times. It is thus expected that the achievement of computer-aided process planning (CAPP) could shorten the preparation time for realizing highly efficient parts machining. Therefore, a CAPP system has been developed by recognizing machining features in previous studies, is reconfigured to match with the characteristics of sliding headstock automatic lathes. The reconfigured CAPP system calculates a machining process that removes material in the order of distance from the ends of a workpiece. Machining operations conducted in parallel by each turning spindle are allocated based on the estimated machining time to reduce the wait of turning spindles. A case study shows usefulness to promptly start parts machining by means of a sliding headstock automatic lathe with the reconfigured CAPP system.