Analysis of the Welding Type and Filler Metal Influence on Performance of a Regenerated Gear

Abstract

This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient.

Exploitation Characteristics of Teeth Flanks of Gears Regenerated by Three Hard-Facing Procedures

“…The calculation of the techno-economic specific parameters, such as indicator of economic justification of regeneration, coefficient of the exploitation reliability and condition for the economic rationality of regeneration, are not given in this paper. In the previous research, by the authors of this paper, such a calculation was provided for a similar regeneration procedure, which confirms the aforementioned statements [ 1 , 13 , 32 ].…”

“…These results are confirmed by the microstructure recordings, which show that the structure is coarse-grained, needle-like and dendritic, characterized by the high hardness [ 30 ]. By increasing the surface hardness, the teeth’s resistance to wear increases, as well as their service life [ 13 ]. The typical damages that appear on such surfaces are the appearance of initial holes and pitting on the teeth surfaces, which cause the irregular operation of gears.…”

“…The regeneration process with Inox 18/8/6 and EDur 600 is done by hard-facing in two layers, while hard-facing with the other two types of the filler metals (Castolin 2 and UTP 670) is somewhat simpler and faster, Figure 2 a,b. The complete technological process with a detailed description of all the operations for the two types of regenerations is presented in [ 13 ].…”

“…Based on analysis of the available literature, one can conclude that a small number of authors have considered the influence of regeneration on the operational characteristics of gears, especially from the aspect of technological heritage. Various hard-facing methods and their application in the reparation process of gears were considered in the authors’ own investigations [ 9 , 10 , 11 , 12 , 13 ], where results of experimental metallurgical investigations of the repaired gear teeth were analyzed. It was concluded that the damaged gear teeth can be repaired by careful selection of the filler metal and welding technology [ 13 , 14 ].…”

“…Various hard-facing methods and their application in the reparation process of gears were considered in the authors’ own investigations [ 9 , 10 , 11 , 12 , 13 ], where results of experimental metallurgical investigations of the repaired gear teeth were analyzed. It was concluded that the damaged gear teeth can be repaired by careful selection of the filler metal and welding technology [ 13 , 14 ]. The service life of gears regenerated by hard-facing is close to the service life of the newly manufactured ones.…”