In order to reduce the lead-time and cost, many useful methods have been applied to Rapid Prototyping (RP) in recent years. But cutting process is still considered as one of the effective RP methods that have been developed and currently available in the industry. It also offers practical advantages in aspects of precision and versatility. However, traditional 3-axis NC machining has some inherent limitations such as the restriction of tool accessibility and the complex setup. In this work, a new rapid prototyping system with high speed 5-axis machining of plastics has been developed to overcome those limitations. And cutting experiments were conducted to determine the design factors of the system and the cutting conditions of plastics. The architecture of developed system is described in detail and the successful application examples are presented.
Since productivity and product quality are always regarded as important issues in manufacturing technologies, a reliable method to predict machining errors is essential to meet these conflicting requirements. In this study, a new method, named ‘Ridge method’, is proposed for the effective prediction of the geometrical roughness and the surface topology under highly efficient machining conditions. Theoretical analysis of a machined surface texture was performed considering the actual trochoidal trajectories of cutting edge. The characteristic lines of cut remainder are defined as three-types of ‘Ridges’ and their mathematical equations are derived from the surface generation mechanism of ball-end milling process. The procedures for the evaluation of the maximum surface roughness and the shapes of the cut remainder are also presented employing the ridge method. The shapes and the heights of the cut remainder are estimated by overlapping adjacent ridges in consideration of the various machining parameters: the feedrate, the path interval, and two types of cutting modes. The predicted results are compared with the values estimated by the conventional roughness model. A series of experimental works is also performed in order to validate the proposed method under various cutting conditions. The agreement between the results predicted by the proposed method and the values calculated by the simulation method shows that the analytic equations presented in this work are useful for evaluating a geometrical surface roughness of milling process.
