Metastable Austenitic Stainless Steel Tool For Magnetic Abrasive Finishing

CIRP Annals - Manufacturing Technology 60 (2011) 339–342 Contents lists available at ScienceDirect CIRP Annals - Manufacturing Technology jou rnal homep age : ht t p: // ees .e lse vi er. com/ci rp/ def a ult . asp Metastable austenitic stainless steel tool for magnetic abrasive finishing H. Yamaguchi a,*, J. Kang a, F. Hashimoto (1)b a b Department of Mechanical and Aerospace Engineering, University of Florida, 226 MAE-B, Gainesville, FL 32611, USA Technology Center, The Timken Company, OH, USA A R T I C L E I N F O A B S T R A C T Keywords: Finishing Burr Magnetic abrasive finishing Through selective heat treatment, a metastable austenitic stainless steel tool can be fabricated to exhibit alternating magnetic and nonmagnetic regions. Magnetic abrasive is attracted to the borders of the magnetic regions of the developed tool to create additional finishing points. In combination with a multiple pole-tip system, this unique magnetic property facilitates simultaneous finishing of multiple regions for shortening finishing time. This paper describes the fabrication, the crystalline structure, and the resulting magnetic properties of the heat-treated tool. The magnetic abrasive behavior, the finishing characteristics, and a mechanism to extend the finished length are clarified for internal finishing flexible capillaries. ß 2011 CIRP. 1. Introduction Flexible capillaries, which have inner diameters smaller than 1 mm and incorporate multiple slots, are widely used in medical applications (e.g., coronary stents and catheter shafts) and in precision analytical instruments. In addition to the tube wall thickness and material, the flexibility of capillary tubes is controlled by patterns of multiple slots made in the tube walls by laser machining [1,2]. During the laser machining process, resolidified material adheres to the inner surface or the cut edges and forms hard heat-affected burrs (up to 100 mm in height) that project inside the capillary tubes. These burrs must be removed completely in a subsequent process. Chemical and microabrasive blasting processes are commonly used for deburring flexible tubes [3–5]. However, deburring tools, including chemical reagents and abrasive media, cannot be easily introduced, or adequately controlled, especially inside long flexible capillary tubes. Moreover, disposal of the chemical reagents often contributes to the destruction of the environment. It is, therefore, desired to develop a new alternative process for internal finishing of the long flexible capillary tubes. A magnetic abrasive finishing (MAF) process has been studied to address the abovementioned problems [6,7]. The MAF process removes material by m