Int J Adv Manuf Technol (2003) 21:91–97 Ownership and Copyright 2003 Springer-Verlag London Limited
Polishing of Ultra-clean Inner Surfaces Using Magnetic Force Jeong-Du Kim* Department of Mechanical Engineering, Sejong University, Seoul, South Korea
In this study, an internal polishing system using magnetic force was developed for the production of ultra-clean tubes with average surface roughness ranging from 0.02 m to 0.05 m or less, and the application of magnetic abrasives composed of WC/Co powder was developed. After finding the optimal conditions, machining characteristics using newly developed abrasives ware analysed. From the results obtained by the experimental design method, optimal polishing conditions were analysed. Keywords: Internal polishing, Magnetic abrasives, Magnetic force, Optimal condition, Ultra-clean surface
1. Introduction The technology for internal polishing is needs ultra-clean machining for the prevention of corrosion and pollution of parts such as vacuum tubes, sanitary tubes and high purity gas tubes, which are used in high-technology industries and are difficult to finish by conventional finishing methods. Previous polishing methods for producing ultra-clean surfaces such as electrochemical polishing (ECP) and magneto-electrolytic abrasive polishing (MEAP) have been used; however, they have two shortcomings, as follows [1]. Firstly, a high cost was incurred for the production of an ultra-clean surface and, secondly, environmental pollution from the use of electrolytic treatment resulted. Therefore, magnetic abrasive machining which uses magnetic force as a machining pressure recently has been developed for the efficient and precision finishing of surfaces. The process is driven to a solenoid using various magnetic abrasives. Recently, Sinmura et al. [2–4] have reported experimental results for internal finishing using a mixed-type of magnetic abrasive, magnetic abrasive only and a magnetic pole, including Al2O3 abrasive. Suzuki et al. [5] have studied a new dressing method for superabrasive wheels using a magnetic abrasive composed of WC+/Co powder. After finding the optiCorrespondence and offprint requests to: J.-D. Kim, Department of Mechanical Engineering, Sejong University, 98 Kunja-Dong, Kwangjin-Ku, Seoul 143-747, South Korea. E-mail:
[email protected]
mal condition for each, the machining characteristics using the newly developed abrasive were analysed. From the results obtained by the experimental design method, the optimal condition was analysed.
2. Theoretial Analysis 2.1 Principle of the Process
Figure 1 shows the magnetic abrasive process for internal polishing. The principle of magnetic abrasive machining utilises the machining force generated by the magnetic field strength as well as the gradient of the magnetic field. This gradient produces an attractio