Study of the Fitting Strength Between Ceramic and Metal Elements with the Use of a Shrink Fitter at Elevated Temperature : Proposal of the Shrink-Fit Method with the Use of a Shrink Fitter and Experimental Results

Abstract

A new method of obtaining shrink fir between a ceramic shaft and an outer metal ring by means of a shrink fitter is reported in this paper. This shrink fitter, which is ring-shaped and has a higher coefficient of thermal expansion than the outer ring does, was inserted between the ceramic shaft and the outer ring. The shrink fitter was cut in the radial direction into several pieces. The fitting strengths of these shrink-fitted assemblies were measured from room temperature up to 600°C°C. The effect of the number of cuttings in the shrink fitter on the fitting strength at elevated temperatures was researched. It was revealed that the cutting of the shrink fitter into three pieces or more was requisite to ensure the fitting strength at elevated temperatures. It was possible to design the fitting strength-temperature relationships by changing the thickness of the shrink fitter in the radial direction. For example, the fitting strength would increase with temperature when the shrink fitter was sufficiently thick, and the fitting strength would decrease with temperature when the shrink fitter was sufficiently thin. Expressions which estimate the fitting strengths of the shrink-fitted assemblies are also developed in this paper.