•Application of developed material, stress and multiaxial fatigue model to a set of bevel gear tests.•Accurate failure prediction of the majority of wheel-initiated tooth flank fractures.•Methodology ...capable of differentiating and predicting surface and subsurface fatigue in gears.•Fractographic analysis of subsurface failures, revealing elongated MgO-Al2O3 cluster in initiation site.•Proposal of a reiterated lifetime factor based on the Maximum Likelihood Method.
A material model for carburized CrNiMo steel and an advanced shear stress intensity, multiaxial fatigue criterion against surface and subsurface fatigue in bevel gears have been developed and presented in earlier publications. This study assesses the accuracy of the proposed methodology by comparing it to load-controlled bevel gear tests at varying hardening layer thicknesses. The dominant failure mode was wheel-initiated tooth flank fracture. Fractographic analysis by means of scanning electron microscopy revealed a severely elongated MgO-Al2O3 cluster in the only pinion-initiated tooth flank fracture. By correlating the calculated material utilizations and the number of cycles to failure, a reiterated lifetime factor is presented. The refined methodology is shown to be capable to differentiate between and accurately predict pitting and subsurface fatigue under well-defined test conditions.
A new steel-plastic gear set testing methodology has been developed at the Institute of Polymer Technology (LKT). The in situ gear test rig analyses the timing differences between the index pulses of ...rotary encoders on the input and output shaft. This measurement principle enables the continuous measurement of the elastic tooth deflection on the one hand and permanent deformations and wear on the other hand by switching between a high loading torque and a low measuring torque. However, the elastic tooth deflection measurement using this principle has not yet been validated. Therefore, in situ gear tests using polybutylene terephthalate (PBT) gears were performed to evaluate the elastic tooth deflection of the plastic gear during operation. The results were compared to the results of pulsator tests. The comparison shows a very good correlation between the results of the newly developed in situ gear test rig and the well-established pulsator test rig. However, it has been shown that the test rig design creates a measuring offset due to angular displacements of the shafts due to torsion of test rig components.
The wear behaviour of PBT-steel gear sets under temporarily changed load has been investigated using an in situ gear test rig developed at the LKT. The in situ test method is based on analysing the ...timing differences between the index pulses of rotary encoders on the input and output shaft of the test rig. The loading torque was varied between two levels and compared to the permanently applied equivalent average load in terms of the resulting tooth flank wear. Moreover, the number of load changes has been varied to analyse the influence of load changes on the gear wear. The results show that the applied load spectrum determines the resulting tooth flank wear even if the average applied load is the same. Moreover, it could be shown that the sequence of the applied load, i.e., the load history, plays an important role, since the applied load and the duration of the applied load within the run-in-stage disproportionately affect the wear behaviour over time.
Gear wheels, the first examples of use in the Mesopotamian period, continue to develop with different forms and features together with advanced technologies. Within the scope of this study, the DMLS ...(direct metal laser sintering) technique, which is one of the latest technologies, was preferred as a method in the production of gears. A total of four different samples, including gears designed as hexagonal, radial, and gyroid lattice designed as lightweight, and gears using porous structure obtained with the DMLS hatch distance parameter, were compared in terms of mechanical strength. The tooth-breaking behaviors of the models tested in the physical test setup specially designed for the study were examined by SEM (scanning electron microscope), and the results were shared.
Industry 4.0 is a synonym for the confluence of technologies that allows the integration of information technology, data science, and automated equipment, to produce smart industrial systems. The ...process of inserting new technologies into current conventional environments involves a wide range of disciplines and approaches. This article presents the process that was followed to identify and upgrade one station in an industrial workshop to make it compatible with the more extensive system as it evolves into the Industry 4.0 environment. An information processing kit was developed to upgrade the equipment from an automated machine to an Industry 4.0 station. The kit includes a structure to support the sensor and the data processing unit; this unit consisted of a minicomputer that records the data, graded the performance of the components, and sent the data to the cloud for storage, reporting, and further analysis. The information processing kit allowed the monitoring of the inspection system and improved the quality and speed of the inspection process.
An in situ gear test rig has been developed at the Institute of Polymer Technology (LKT) to characterize the deformation of plastic gears during operation. It analyses timing differences between ...following index pulses of rotary encoders on the input and output shaft. This measurement principle enables the continuous measurement of the elastic tooth deformation and permanent deformations and wear at operating speed by switching between a high and low torque. Gear tests using a steel-polybutylene terephthalate (PBT) gear set were performed at different rotational speeds and tooth temperatures to analyze the tooth deformation during operation. The results were compared to the calculated deformation according to gear design guideline VDI 2736. Moreover, the results of the gear tests were correlated with the results of a dynamomechanical analysis (DMA). Both, the DMA and the in situ gear tests show that the effect of temperature on deformation is much higher than the effect of frequency or rotational speed. However, the experimentally measured tooth deformation is significantly higher (up to 50%) than the calculated at lower speed. Thus, the check calculation according to VDI 2736 underestimates the actual tooth deformation at lower speeds. Therefore, the guideline should be adjusted in the future.
Due to their cost-effectiveness, pulsator tests are widely adopted as a testing methodology for the investigation of the effects of material and heat and surface treatment on the gear strength with ...respect to tooth root fatigue fracture. However, since no meshing contact is present in pulsator tests, there are differences between the test case and the real-world application scenario where gears are rotating under load. Those differences are related to both statistical and fatigue phenomena. Over the years, several methodologies have been developed in order to handle this problem. This article summarizes them and proposes a first comparison. However, no complete comparison between the different estimation methodologies has been conducted so far. This article aims to partially cover this gap, first by presenting and comparing the methodologies proposed in the literature and then via a deeper comparison between two different elaboration methodologies. Those two methodologies, which have been developed by examined to the same test rig configuration, are also discussed in detail. The comparison is performed based on an actual database composed of 1643 data points from case-hardened gears, divided into 76 experimental campaigns. Good agreement between the estimated gear strengths was found. The database is also adopted in order to make further considerations about one methodology, providing additional validation and defining the specimen numerosity required.
Over the years, transmission system plays a vital role in automobile industry in order to improve the performance of vehicle. Since 323 BC to till date gears plays a vital role in building the ...integral parts of washing machines, gear pumps, gear motors and wrist watches and so on. The lot of gear applications are extended in all sector of transmission mediums, without gear elements most of the transmission become invaluable in modern engineering industry. This paper aims to design and analysis of gear testing kit, for testing the load generation developed on the gear tooth through brake drum. The main objective of this work is to design the components in a gear testing kit and the components involved in the gear testing domain, are modelled using CATIA software. The main components in our paper are 1/2hp motor, coupling; shaft and bearing, mating gears are made of same dimensions and of different materials. Further the work is to analyse the mating gears which are made of same material and analysis are carried through ANSYS software. Static Structural Analysis is carried through ANSYS analytical Software. Two types of plots are performed and their corresponding Von - Misses stress and Total Deformation at three different torque levels are evaluated.
► Contact fatigue performance of coated gears in comparison to uncoated gears. ► Enhancement of contact fatigue life of gears with surface coatings. ► Evaluation of hard and soft surface coatings for ...gears. ► Assessment of hard and soft coatings for gears. ► Surface coatings for gears.
The objective of this study was to evaluate the performance of helical gears with applied surface coatings either with or without Inorganic Fullerence Like Material (IFLM) nano-particles. The contact fatigue performance of case-carburised and tempered S156 steel helical gears coated with Balinit C1000, Balinit C*, CrN+IFLM, C6+IFLM and Nb–S coatings were tested using a 91.5mm centre distance back-to-back test rig. The constant torque, constant speed contact fatigue tests were carried out for up to 50 million cycles to evaluate the performance of the different coatings in comparison with the uncoated, as-ground condition. The endurance contact fatigue tests were conducted at two different contact stress levels with the performance assessed against the extent of micro-pitting damage and the associated average gear tooth profile deviation. It has been found that gears coated with Balinit C showed the lowest micro-pitting damage followed by those with C6+IFLM and Nb–S coatings. The Nb–S coated gears showed the lowest gear profile deviation followed by those coated with Balinit C. Other coatings tested resulted in large gear tooth profile deviations below the pitch diameter. From the results of gear testing, it is concluded that the Nb–S coated gears showed the best overall contact fatigue performance, followed by Balinit C coated gears that gave minimum micro-pitting damage and low levels of gear tooth profile deviation.
The effect of surface features on as-ground gears and the influence of BALINIT® C and Nb–S coatings on the initiation of micro-pitting damage have been examined in case-carburised and tempered S156 ...steel helical gears subjected to contact fatigue using back-to-back gear testing. The initiation of micro-pitting damage has been studied using scanning electron and optical microscopy examination. It has been observed that micro-cracks tend to initiate against the sliding direction preferentially from micro-valleys on the surface of as-ground gears, particularly when the depth of micro-valley is favourably oriented at an angle against the sliding direction. It has been found that the micro-pitting damage is drastically reduced in both coated gears. In BALINIT® C coated gears, the micro-scale surface irregularities are removed by a wear process resulting in a polished surface of the gear flank below the pitch diameter which is attributed to the effect of hard BALINIT® C coating. However, there is region of interface between the polished and unpolished regions of gear flank where there is small scale initiation of micro-pitting due to the absence of BALINIT® C coating at micro-valleys. In Nb–S coated gears, the coating tends to penetrate and fill-up the micro-valleys on as-ground surface modifying the gear flank surface. Hence, the micro-pits tend to initiate only at some micro-valley sites where the Nb–S coating is locally removed during running. This study shows that, both BALINIT® C and Nb–S coated gears show enhanced resistance to micro-pitting damage by removing localised stress concentration at micro-valleys present on as-ground gears.
► Origin of micro-pitting in gears. ► Micro-pitting in as-ground and coated gears. ► Initiation of micro-pitting in uncoated and coated gears. ► Resistance to micro-pitting in coated gears. ► Contact fatigue behaviour of as-ground and coated gears.
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