Precision Case Hardening by Low Pressure Carburizing (LPC) for High Volume Production*

Abstract

KurzfassungTraditionally, case hardening is based on carburizing in atmospheres and oil quenching; this is carried out in sealed quench furnaces and in continuous lines (pusher, roller or rotary furnaces). ey are technologies and devices developed more than 50 years ago and, over the course of time, they have exhausted their development potential. At present, they hardly meet the incoming requirements of the modern industry regarding quality and replicability, integration and organization of production, and environment protection.A solution for weak points of traditional case hardening is the use of vacuum technologies and equipment. Vacuum carburizing increases the resulting precision and replicability, and the variety of vacuum equipment for heat treatment allows the adaptation to modern industry requirements. Two applications are described in the article. e rst one -evolutionary -is based on the triple-chamber vacuum furnace for semi-continuous production as a wide alternative for traditional devices. e second system -innovative -is based on the true single-piece ow method. Both solutions have specific and characteristic properties that predispose them for different applications depending on quality requirements and organization of production. n

The Influence of the Depth of Grinding on the Condition of the Surface Layer of 20MnCr5 Steel Ground with the Minimum Quantity Lubrication (MQL) Method

“…The analysis of information on the types of heat treatment currently applied before grinding shows that carburising followed by quenching is one of the most commonly used methods of the surface heat treatment. Low-pressure carburising [5,6] is superior to conventional carburizing [7,8] in terms of efficiency and features a number of advantages, including lack of internal oxidation and higher uniformity of obtained layers. It should be remembered that residual stresses that have arisen as a result of thermochemical treatment (TCT) are present in the base and surface layers.…”

Algorithm Scheme to Simulate the Distortions during Gas Quenching in a Single-Piece Flow Technology

“…Avoiding distortions is cost-effective for the quality control of chemically treated steel elements. As an example, gears with large distortions can produce more noise and have shorter durability [1,2]. Furthermore, the correction of distortions is one of the most expensive processes [3][4][5].…”

“…LPC and HPGQ, when compared with traditional methods, have shown better results [8][9][10][11]. Moreover, the single-piece flow model takes every single element through the exact same position and process conditions as the others, avoiding variations in the physical and metallurgical characteristics over the placement that the element occupies [2,3,12,13]. Additionally, in a 4D quenching chamber, the inflow of cooling gas from all sides and the rotation of parts are performed to support a uniform cooling effect [14,15].…”