The Effect of Chip Binding on the Parameters of the Case-Hardened Layer of Tooth Surfaces for AMS 6308 Steel Gears Processed by Thermochemical Treatment.

Robert Fularski,Ryszard Filip

doi:10.3390/ma14051155

Abstract

The following article describes influence of pressure welded or bound chips to the gear tooth flank and/or the tooth root on a carburized case and surface layer hardness of Pyrowear 53 steel gears, machined by Power Skiving method. This paper is focused only on one factor, the chips generated while forming gear teeth by power skiving, which could result in local changes in the carburized case parameters as a negatively affecting point of mechanical performance of the carburized case. The chips, due to the specifics of the power skiving process and the kinematics of tooth forming, could be subject to the phenomena of pressure welding or binding of chips to the tooth. During the carburizing stage of the downstream manufacturing processes, the chips form a diffusion barrier, which ultimately could result in localized changes in the carburized case. This work was an attempt to answer the question of how and to what extent the chips affect the case hardening. Performed simulations of chips by a generating cupper “spots”, mentioned in the study, represent a new approach in connection with minimization of errors, which could appear during carbon case depth and case hardness analysis for typical chips, generated during the machining process—assurance that a complete chip was bound to the surface. Hardness correlation for zones, where the chip appears with areas free of chips, gives simple techniques for assessment. Performed tests increased the knowledge about the critical size of the chip—1.5 mm, which could affect the case hardening. Obtained experimental test results showed that the appearance of chip phenomena on the gear tooth might have a negative impact on a carburized case depth and hardened layer.

Highlights

The research described further in this paper focuses on presenting the effect of chips which, in the case of a poorly performed tooth forming manufacturing process upstream of the thermochemical processing or limited understanding of the issue, may cause localized reduction in hardness in the areas interesttool on the surface, followinggear) the processes intended improve phases whereofcutting feedtooth fa
The research described further in this paper focuses on presenting the effect of chips which, in the case of a poorly performed tooth forming manufacturing process upstream of the thermochemical processing or limited understanding of the issue, may cause localized reduction in hardness in the areas of interest on the tooth surface, following the processes intended to improve the mechanical performance of a surface layer exposed to high loads
The outcome of effect may cause a localized reduction in hardness of the surface this effect may cause a localized reduction in hardness of the surfacelayer

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. While the phenomena which occur during machine cutting or abrasive machining process and their effect on the surface layer are widely discussed in the available references [9,10,11,12,13,14,15,16,17,18] and the industry norms applied in the assessment of microstructure, the question of machining prior to case carburizing of the surfaces to be exposed to considerable and dynamically variable loads is less extensively detailed in research work It is known, that certain external factors related to machining could result in local changes in the carburized case parameters to a point capable of negatively affecting the mechanical performance of the carburized case.

Double

Test Material and Methodology

11. Waviness

12. Localization

Conclusions