Int J Adv Manuf Technol (2002) 20:180–189 Ownership and Copyright  2002 Springer-Verlag London Limited A Cost-Effective Thickness Measurement Technique for Engine Propellers M. K. Lam 1 , S. F. Lee 1 , P. Iovenitti 2 and S. H. Masood 2 1 Department of Industrial Engineering and Management, Hong Kong Institute of Vocation Education (Tsing Yi), Tsing Yi, Hong Kong; and 2 Industrial Research Institute Swinburne (IRIS), Swinburne University of Technology, Victoria, Australia This paper describes the design and development of a precision calliper system to measure the surface profile of an outboard marine engine propeller blade. Several instruments that are commonly used for measuring the surface profile of a propeller blade are reviewed in this paper. These include the pitch meter, the profilometer and the computer numerical control coordinate-measuring machine (CNC-CMM). However, the operating practices and availability of different facilities in industry necessitate a more cost-effective approach. An alterna- tive method using a precision calliper system is therefore proposed. Details of the design criteria, principles of operation and the testing and verification of the system are presented. The paper concludes that the precision calliper system is a cost-effective method for measuring the surface profile of a propeller. Keywords: Metrology; Profilometry; Propellers; Surface measurement; Thickness measurement 1. Introduction The accurate measurement of the surface profile is important for the development of high-performance marine propellers. Although a number of methods are available for measuring a propeller profile, there appears to be a need for a more cost-effective approach. This paper describes the design and development of a cost-effective surface profile measurement system. The scope of this paper includes the design, develop- ment, calibration, and testing of a precision calliper system for propeller blade thickness measurement. Our aim was to investigate an efficient and effective tech- nique for dimensional measurement of propeller blades, and particularly, to develop a cost-effective alternative to existing techniques such as the use of a computer numerical control coordinate measuring machine (CNC-CMM). The concept Correspondence and offprint requests to: Mr M. K. Lam, Hong Institute of vocation Education (Tsing Yi), 20 Tsing Yi Road, Tsing Yi Island, NT, Hong Kong. E-mail: mklaMvtc.edu.hk Fig. 1. Definitions of the co-ordinates of a propeller. developed in this paper is used to design the necessary fixture for measuring the blade thickness of an outboard marine propeller. The measured data are subsequently used as a basis for improving the propeller design by changing the profile using a CAD/CAM/CAE system. Thus, the present work may be considered as an important step toward the improvement of propeller performance. This paper presents the development of a precision calliper system, which is a novel technique for surface profile measure- ment that can be employed in-house without an expensive computer numerical control coordinate machine. 2. Surface Profile Measurement of a Propeller Blade The surface profile of a propeller blade has a significant effect on the propeller’s performance. During the development stage of a new product, it is important to determine the exact geometry (see Figs 1 to 3) for a description of the propeller geometry of an existing propeller in order to develop an improved design. Furthermore, once a design has been put into full-scale production, it is also important to ensure that the product conforms to the specifications of the profile.