Comparison of Bending Fatigue Strength among Spur Gears Manufactured by Various Methods (Influence of Manufacturing Method on Bending Strength)

Abstract

This paper deals with an experimental evaluation of bending fatigue strengths for hobbed, forged, sintered and austempered ductile iron (ADI) spur gears. The module is 2.5 and the number of teeth is 26 in the test gears. The materials of the test gears are SCr420H for hobbed and forged gears, prealloyed powder metal with 1.5 wt.% Mo for sintered gears, and FCAD 1100-15 for ADI gears. All gears except ADI gears were carburized. The pulsator bending fatigue tests were carried out for the test gears. Then the relationship between the strength and the manufacturing cost is obtained. The forged gear has the high strength of 3% and low cost compared with the hobbed gear. It is the best among the four gears. The sintered and ADI gears have approximately half the strength and cost of the hobbed gear. These gears are effective when cost is a high priority. In the progress of the fatigue tests, comparisons of strength among gears having different tooth-root forms were needed. The nominal stress obtained from actual measured profile data using a noncontact-type measuring machine is suitable for comparing the fatigue strength in gears having different root forms.

Tooth root bending fatigue strength of small-module sinter-hardened spur gears

“…This production would consistently increase if PM technology could provide, in a cost-efficient way, parts having better fatigue performances, comparable to the ones of wrought equivalent parts. With this purpose, many studies have been focused on characterisation of the fatigue behaviour of sintered steels [1–9]. Among different automotive components, gears are the ones that led to a significant cost savings when the wrought alloys are converted to net shape or near-net shape P/M parts.…”

Meshing Simulation and Strength Calculation of a Carburized Gear Pair

“…Some scholars [7,8] observed the microstructure properties of carburized gears to find the initiation and extension of damage; however, this method is only applicable to some specific materials and conditions. Yamanaka et al [9] used four different manufacturing methods for spur gears and found that forging is the best way to increase bending stress of carburized gears. Zwolak and Palczak [10] studied the influence of two treatment methods on contact strength of gears by analysing the characteristic of surface layer, which did not involve bending and shear stresses.…”

Tooth Root Bending Fatigue Strength of High-Density Sintered Small-Module Spur Gears: The Effect of Porosity and Microstructure

“…This clearly impacts on the stiffness, tensile, fatigue and wear properties of such components [2][3][4]. In the context of P/M gears, (i) the lower stiffness is detrimental to the mesh precision and mesh power loss factor [5], (ii) inferior fatigue properties negatively affect tooth root bending fatigue strength [6] and pitting resistance [7], and (iii) sintered tooth flanks have higher wear rates [8]. To combat these adverse effects, many treatments have been devised so far, such as shot peening [9], surface rolling [10], sinter-forging [11], and the double press double Metals 2019, 9,599; doi:10.3390/met9050599 www.mdpi.com/journal/metals Metals 2019, 9,599 2 of 14 sinter process [12].…”