INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3, pp. 419-427 JUNE 2010 / 419 DOI: 10.1007/s12541-010-0048-6 1. Introduction Plate cam mechanism is a widely used machine component with the continuous contact motion of cam and follower, and can easily produce any functional motion of follower due to the rotation of cam. Cam mechanism has the diverse types by the combination of different shape of cam and motion of follower; plate or cylindrical cam, roller or flat-faced follower, and reciprocating or oscillating motion. In spite of the advantages of a few number of links, simple structure, positive motion, and compact size, cam mechanisms require the accurate shape design and precise machining procedures for satisfying the mechanical requirements. Under the low leveled design and manufacturing, cam mechanisms give the heavy effects on vibration, noise, separation, and overloading to an overall system. To avoid these effects, cam mechanism must be well designed accurately and machined precisely. Actually, a hybrid CAD/CAM approach may be the best solution that the shape data from the design process are directly combined to the machining data for the manufacturing process. Line interpolation and circular interpolation are commonly used in construction of the machining data from the profile data of cam. Line interpolation has the low accuracy and circular interpolation can not keep the accuracy because of the disconnective radii of curvatures or the discontinuous slopes at the connected point by two circular arcs as presented in Shin et al.. 1-3 Recently, parameteric interpolation using B-spline and NURBS curve are suggested in Jung et al. 5 and Yang et al.. 6 Also biarc interpolation is widely used and deeply dependent on the direction angle toward centers of biarc curves. Bolton 7 described a biarc curve based on the tangential angles at two points, Parkinson and Moreton 8 made a biarc curve based on a quadratic equation at three points, Meek and Walton 9 used spline types for constuction of biarc curve. Schonherr 10 introduced an approach to minimize the radii of biarc curves. Commonly these interpolation methods make the machining points increasing and then the excessive data for machining a curved shape make the machining errors increased. Thus, the precise machining process requires minimization of the machining points to keep the accuracy under a given machining tolerance. This paper introduces 3 steps of a hybrid CAD/CAM A Hybrid Approach for Cam Shape Design and Profile Machining of General Plate Cam Mechanisms Joong-Ho Shin 1 , Soon-Man Kwon 1 and Hyoungchul Nam 1,# 1 Department of Mechanical Design & Manufacturing, Changwon National University, #9, Sarim-dong, Changwon, Kyungnam, South Korea, 641-773 # Corresponding Author / E-mail: nhchul@changwon.ac.kr, TEL: +82-55-267-1106, FAX: +82-55-267-1106 KEYWORDS: Plate cam mechanism, Cam, Follower, Shape design, Profile machining, Contact point, NC data, Instant velocity center, Biarc curve fitting Plate cam mechanism can easily produce the positive and functional motions in contact of cam and follower. Generally cam mechanism is used in many fields of mechanical control, automation, and industrial machinery. To obtain the accurate motion of follower, the profile of cam must be designed and machined precisely. This paper proposes an instant velocity center method for the profile design and a biarc fitting method for the profile machining to 4 different types of plate cam mechanisms with reciprocating or oscillating motion and roller or flat- faced followers. The key of this paper is the introduction of a hybrid system combined the design procedures and the manufacturing procedures. The main idea is that the minimum machining data are built by the accurate biarc curves fitted directly from the design parameters. The radial direction angles toward biarc centers for the accurate biarc curve fitting can be defined directly by the contact angle of cam and follower given in the design procedures. An application of the proposed approach is verified the accurate profiles of a designed cam and a machining cam using the minimum NC data within a given machining tolerance. Manuscript received: July 16, 2009 / Accepted: February 18, 2010 © KSPE and Springer 2010