Distortion Control through Synchronized Vacuum Heat Treatment

Abstract

AbstractControlling distortion is of key importance during the case hardening process for the production of automotive and non-automotive metallic components. By effective control of distortion and the variation of distortion, significant costs in post heat treatment machining processes can be avoided. In some cases it is even possible to eliminate all post-machining. In other cases it may be possible to avoid the press-quenching of individual components, resulting in huge cost-benefits. A recently introduced new vacuum furnace design allows the treatment of small batches in a single layer of parts (“2D-treatment”) which allows for easy automated loading and unloading of the fixture-trays. By using the small batch concept, a continuous flow of parts can be established (“One Piece Flow”). There is no need to wait until enough parts are collected to build a large batch with multiple layers (“3D-batch”). This compact furnace unit can be implemented into the heart of the production chain and provides heat-treatment processes which can be fully synchronized with the green and hard machining-operations. When performing case hardening, the components are Low Pressure Carburized (LPC) at high temperatures (1050 °C) followed by gas quenching. The treatment in single layers offers an optimum in quality regarding: temperature homogeneity, quench homogeneity and distortion control. Typical components for this technology come from the automotive, aerospace and tool industry. The directly following contribution in this Journal (A. Schüler et al., p. 90–98)shows more results achieved with this technology on selected truck-components such as gears and sliding-sleeves.