Author(s)

D. Stratton & C. Sorensen

Abstract

Quantitative understanding of frictional phenomena between the tool and the workpiece is essential for accurate modeling of the Friction Stir Welding (FSW) process. A method of measuring the tool-workpiece interface is proposed that allows frictional measurements to be made in a non-oxidizing environment under extreme conditions. The ranges of temperature, velocity and normal force are 100–600 ◦C, 75–400 surface feet per minute, and 100–600 lbf, respectively.Data is gathered at different parameter level combinations to provide enough data to create an empirical model representing the data. Two different friction modes are observed which have distinct characteristics. One mode, Coulomb friction, has frictional force proportional to normal force while the other, plastic shear deformation friction, has frictional force independent of normal force. A linear statistical model has been developed to characterize each of the frictional modes for the Polycrystalline Cubic Boron Nitride (PCBN) tool and 1018 steel work piece interface as functions of temperature, velocity, and normal force. Keywords: sliding friction, model, steel, Polycrystalline Cubic Boron Nitride (PCBN), large normal forces, temperature, velocity, measurement, friction stir welding (FSW), finite element. 1 Introduction Friction Stir Welding (FSW) is a solid-state joining process where a non-consumable tool deforms two workpieces along the interface to form a union between the two workpieces. This welding process gained popularity over the past decade. However, this process is relatively young and our understanding of it is insufficient.

Keywords

sliding friction, model, steel, Polycrystalline Cubic Boron Nitride (PCBN), large normal forces, temperature, velocity, measurement, friction stir welding (FSW), finite element.