Plastic Gears Research Articles

Fatigue and Wear Performance of Autoclave-Processed and Vacuum-Infused Carbon Fibre Reinforced Polymer Gears

This study focuses on investigating the fatigue and wear behaviour of carbon fibre reinforced polymer (CFRP) gears, which have shown promising potential as lightweight and high-performance alternatives to conventional gears. The gears were fabricated via an autoclave process using an 8-layer composite made of T300 plain weave carbon fabric and ET445 resin and were tested in pair with a 42CrMo4 steel pinion and under nominal tooth bending stress ranging from 60 to 150 MPa. In-situ temperature monitoring was performed, using an infrared camera, and wear rates were regularly assessed. The result of the wear test indicates adhesive wear and three-body abrasion wear mechanisms between the CFRP gears and the steel counterpart. A finite element analysis was performed to examine the in-mesh contact and root stress behaviour of both new and worn gears at various loads and a specified running time. The results point to a substantial divergence from ideal meshing and stress conditions as the wear level is increased. The fatigue results indicated that the CFRP gears exhibited superior performance compared to conventional plastic and composite short-fibrous polymer gears. The described composite gear material was additionally compared with two other composite configurations, including an autoclave-cured T700S plain weave prepreg with DT120 toughened resin and a vacuum-impregnated T300 spread plain weave carbon fabric with LG 900 UV resin. The study found that the use of the T700S-DT120 resulted in additional improvements.

Test Rig for the In Situ Measurement of the Elastic Tooth Deflection of Plastic Gears

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.

Circular and lower impact mussel and seaweed aquaculture by a shift towards bio‐based ropes

AbstractWorldwide, current mussel and seaweed aquaculture practices contribute to the increase of fossil fuel‐based plastic gears at sea, leading to marine litter and microplastics generation. Smart aquaculture has a great potential for shifting towards the use of lower impact bio‐based and biodegradable gears. This review defines the value chain of biogears as more sustainable gears for mussel and seaweed aquaculture, and sustainability issues covering technology, environmental impacts, economy‐market, policy, and social drivers for their potential implementation. Fit to purpose durability and functionality attributes, end‐of‐life (EoL) options and environmental benefits are key features for competitiveness of biogears versus conventional fossil fuel‐based aquaculture gears. EoL management for collection, sorting and logistics of biogears to recycling facilities is needed for the up cycling of bio‐based materials thus ensuring application of principles of circularity. The selection of the biopolymers for recyclability, improvement of the polymerisation and recycling processes together with the enhanced deployment of recycling facilities are considered as key factors for eco‐designing of circular biogears. Current policies supporting bio‐based plastics in marine applications and social benefits, as environmental sustainability, healthy products, and circular business opportunities, are likewise added value for the development and use of biogears. Overall, biogears can reduce environmental negative impacts in mussel and seaweed productions, while enabling circular use of bio‐based materials and sustainable circular bioeconomy.

Process Design for Manufacturing Fiber-Reinforced Plastic Helical Gears Using a Rapid Heating and Cooling System

In this study, a lightweight fiber-reinforced plastic (FRP) helical gear was fabricated to investigate the potential application of FRP in automobile parts that require high loads and reduced noise. High-performance aramid FRP processed using the wet-laid method was used in the tooth region, and SCR420 steel was used in the inner hub region. A hot-forming system that combines rapid induction heating and water channel cooling methods was developed to reduce the cycle time. The cooling water flow conditions were analyzed to precisely control the mold temperature. Additionally, a rotating extraction system was developed to mitigate the extraction difficulty owing to the helix angle to the extraction direction. Using the innovative hot-forming system developed in this study, a helical gear without any process-induced defects was fabricated with a significantly reduced cycle time. The performance of the gear was successfully estimated using gear durability, torsional strength, and motion noise tests. The use of FRP materials offers significant potential to realize lightweight components; however, certain challenges related to their properties that may limit their application must be addressed on a case-by-case basis.

Dynamic Modeling and Analysis of Epoxy Gear Considering Material Viscoelasticity

With improvements in lubrication and material strength, the power transmitted by plastic gears has increased significantly. To develop high-performance transmission systems, it is necessary to gain deep insights into the dynamic characteristics of plastic gears. However, because plastics are viscoelastic materials, they do not obey Hooke’s law, which is the basis of traditional gear dynamic models. In this study, a refined dynamic model for an epoxy gear pair considering material viscoelasticity and extended tooth contact is established, and the differences in the dynamic responses between an epoxy and a steel gear pair are compared with respect to the dynamic meshing force and dynamic transmission error. The results show that: (1) the plastic gear can restrain the meshing impact, it has a generally lower dynamic meshing force than steel gear pair; (2) the position accuracy is the weak point of plastic gears, and this is significantly affected by the rotation speed; (3) the way to indirectly evaluate the dynamic meshing force by measuring the dynamic transmission error, which is often used for metal gears and is less effective for plastic gears.

Recent advances in tribological properties of silicon based nanofillers incorporated polymer nanocomposites

Over the last few decades, the demand for the development of polymer nanocomposites is increasing due to their excellent properties of mechanical, thermal, electrical, tribological properties and so on. The diversity of polymer nanocomposites with enhanced performances makes them suitable for a wide variety of applications such as automobile, aerospace, electrical, electronics, construction etc. The effect of various types of nanofillers such as metal-based nanofiller, carbon-based nanofiller, and silicon-based nanofiller incorporated into polymers are widely investigated by various researchers. Silicon-based nanofiller-reinforced polymer nanocomposites are prospective in recent years on tribological applications such as plastic gears, bushes, bearings, etc. A large number of different studies have demonstrated the various excellent properties of silicon-based nanofillers and hybrid nanofillers into polymer nanocomposites, however, limited reviews are being published on the effect of silicon-based nanofillers and hybrid nanofillers reinforced polymer nanocomposites. Therefore, this manuscript aims to review the recent advances on the effect of silicon-based nanofillers and hybrid nanofillers incorporated polymer nanocomposites emphasizing mainly the tribological properties. This work presents the outline of the main outcome from various studies focusing mainly on the effect of silicon-based nanofiller on friction, wear resistance and wear mechanism-related tribological properties. This work also intended to review the effect of silicon-based hybrid nanofillers into polymer nanocomposites on tribological properties. Finally, the challenges and future perspectives of silicon-based nanofillers reinforced polymer nanocomposites on the tribological properties are also discussed.

Improving the wear resistance of 3D printed spur gears through a free-form tooth flank optimization process

Involute gears have traditionally been the preferred choice for gear transmission systems due to their simplicity and interchangeability. However, there are applications where they do not provide the most durable and efficient solution. While the cost of implementing optimized non-involute gears in most applications often outweighs their comparative advantages, the advent of additive manufacturing has opened up possibilities for designers to explore alternative gear tooth profiles. This is particularly relevant in the realm of plastic gears, where optimized non-involute gears produced through 3D printing can address their primary drawbacks, such as surface durability and wear resistance. In this study, a comprehensive free-form optimization process was conducted to determine the optimal tooth profile that minimizes wear on 3D printed spur gears during operation. The tooth flank geometry was represented using a 4th order B-spline curve, and a genetic algorithm was employed to determine the optimum positions of the control points aiming to minimize wear depth across the tooth flanks. The spur gears were manufactured using Fused Deposition Modeling (FDM) with PLA material. The parameters of the additive manufacturing process were experimentally fine-tuned to achieve the best possible accuracy. To evaluate the performance of the optimized free-form gears, two case studies were implemented, demonstrating that the optimized gears achieved a remarkable reduction of average wear depth by more than 50% and a reduction of maximum wear depth by more than 69% compared to standard involute gears. To further validate the effectiveness of the optimization method, experiments were carried out using an FZG test rig. The profiles of the tooth flanks were measured on a Coordinate Measuring Machine (CMM) before and after the experiments to compare the wear depth against the standard involute gears. The results revealed a significant improvement in the wear resistance of the tooth flanks, with a reduction of wear depth of 44.1%.

Plastic gear loss estimates from a major Australian pot fishery

Abstract The quantity of plastic fishing gear lost to the ocean remains largely undocumented despite its importance for understanding the magnitude of fishery contributions to plastic marine debris and mitigating contamination at the source. This study estimated plastic gear loss from a major Australian pot fishery by interviewing 50 commercial fishers from the West Coast Rock Lobster Managed Fishery in 2021 to document the plastic gear components used, the number of pots lost, and the causes for gear loss. The estimated annual percentage of gear lost (10.8%) and rate of “active” gear loss by fishing effort (0.2%) were lower than global estimates for other pot fisheries indicating that plastic gear loss from this commercial fishery is relatively low. Plastic gear loss was attributed to rope (47.0%), pot components (30.7%), and floats (22.3%), of which 78.0% were polypropylene and polyethylene. The composition of pots, measures used to prevent gear loss, and changes to management could influence plastic gear loss from this fishery. This is the first study to examine plastic gear loss from an Australian pot fishery with a dynamic approach that provides robust estimates for better understanding plastic gear loss from fisheries and informing plastic mitigation efforts.

A review on materials and performance characteristics of polymer gears

In this research work an extensive review on use of advance materials and performance of polymer gears. Further, literature on polymer gears has been divided into four divisions based on the type of gear material, performance characteristic, modifications, and manufacturing techniques. Materials like polyamide and acetal and their composites are focused due to their huge application quotient. Use of in total six grades that is, PA6, PA66, PA12, PA46, PA618, and PA645 as gear material have been identified. Use of glass and carbon fiber reinforcements in PA gears with varying percentage in a range of 20%–35% and 15%–30%, respectively have been observed. Failure and performance characteristics such as wear, thermal, fatigue, load, transmission, and operational have been illustrated and described in detail. Research studies to improve thermal performance of plastic gears by modifying gear tooth and its profile has also been discussed along with their effects. Application of advance manufacturing technique such as 3D printed additive manufacturing in producing plastic gears is also talked over in this article. This compiled review work aims to assist researchers in selection of plastic gear material and to explore various factors and parameters affecting the failure behavior and performance of plastic gears.

Development of the fatigue life model for plastic gears of automotive actuators under vibration

In this research, a series of analysis and validation were conducted for estimating the fatigue life of plastic gears. A jig for depicting assembly state in vehicle actuators was made based on failure mechanism analysis. A vibration test for detecting the resonance frequency was performed using a frequency range specified in the ISO standard and it is confirmed that a resonance point occurs within a range generated by an engine operation. Finite element analysis was conducted to obtain the maximum stress in the vibration test applied with a sinusoidal sweep signal and the cycles to failure were calculated through the accelerated testing. The fatigue life model for plastic gears was established by deriving an S-N curve on the relation between stress and cycles to failure. The purpose of this study is to propose a design guideline for improving the reliability of vehicle actuators through the establishment of a fatigue life model for the elemental components.

Lightweight Plastic Gear Body using Gyroid Structure for Additive Manufacturing

Lightweight Plastic Gear Body using Gyroid Structure for Additive Manufacturing

In Situ Measured Tooth Flank Wear of Plastic Gears under Spectrum Loading

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.

Application of mold flow analysis to the study of plastic gear rack injection molding warpage

This study employed the Taguchi method, analysis of variance, and response surface methodology for plastic gear rack injection molding parameters followed by a factorial quality validation. This study was expected to reduce the time cost of mold design and injection molding by making different combinations of the molding parameters, designing an experimental method, and performing the data simulation experiment by computer-aided engineering (CAE). With the research tool of polymer (polyacetal) for plastic material, computer-aided design mold design, and CAE mold flow analysis software, a numerical analysis of plastic molding flow was conducted. Taguchi L16 (45) orthogonal array designed 16 experimental combinations including injection molding conditions of filling time, holding pressure, holding time, plastic temperature, and mold temperature. The experimental results of molding analysis of software (Moldex3D) determined the optimum molding essentials of plastic injection: filling time 0.2 s, holding pressure 98 MPa, plastic temperature 195 °C, and mold temperature 65 °C. In this study, the parameters of the response surface method were used for the actual injection verification. The CAE simulation software can greatly improve the mold design and injection molding parameter testing time to enhance the overall working efficiency and cost control.

成形プラスチック歯車研究専門委員会 プラスチック歯車の高性能化への取り組み，その適用範囲のさらなる拡大を目指して

成形プラスチック歯車研究専門委員会 プラスチック歯車の高性能化への取り組み，その適用範囲のさらなる拡大を目指して

An Effective Shrinkage Control Method for Tooth Profile Accuracy Improvement of Micro-Injection-Molded Small-Module Plastic Gears.

An effective method to control the non-linear shrinkage of micro-injection molded small-module plastic gears by combining multi-objective optimization with Moldflow simulation is proposed. The accuracy of the simulation model was verified in a micro-injection molding experiment using reference process parameters. The maximum shrinkage (), volume shrinkage (), addendum diameter shrinkage (), and root circle diameter shrinkage () were utilized as optimization objectives to characterize the non-linear shrinkage of the studied gear. An analysis of the relationship between key process parameters and the optimization objectives was undertaken using a second-order response surface model (RSM-Quadratic). Finally, multi-objective optimization was carried out using the non-dominated sorting genetic algorithm-II (NSGA-II). The error rates for the key shrinkage dimensions were all below 2%. The simulation results showed that the gear shrinkage variables, , , , and , were reduced by 5.60%, 8.23%, 11.71%, and 11.39%, respectively. Moreover, the tooth profile inclination deviation (), the profile deviation (), and the total tooth profile deviation () were reduced by 47.57%, 23.43%, and 49.96%, respectively. Consequently, the proposed method has considerable potential for application in the high-precision and high-efficiency manufacture of small-module plastic gears.

In situ investigation of the influence of varying load conditions on tooth deformation and wear of polymer gears

A new method for in situ deformation and wear measurement of polymer gears has been developed at the LKT and validated for polyamide-66 (PA66) gears at constant loading torque and rotational speed. This contribution contains a more comprehensive validation of the newly developed test method by examining polybutylenterephtalate (PBT) gears under varying loading conditions. The deformation test method is based on measuring and analysing the timing differences between the index pulse signals of rotary encoders on the input and output shaft of the test rig. Since the total tooth deformation is a combination of different effects, such as elastic and plastic deformation, thermal expansion and wear, different testing modes with a low and a high torque level are implemented to separate the effects of elastic deformation on the one hand and plastic deformation and wear on the other hand. As a consequence, the new test rig design allows a deeper understanding of the wear and deformation behaviour of polymer steel gear sets over time. This potential is used to analyse the interactions of different loading conditions on the time-dependent deformation of plastic gears. The influence of both, different transmitting torques and rotational speeds is examined.The test method shows good correlation with well-established ex situ measurements for different combinations of rotational speeds and loading torques and thus could be validated. Long-term gear tests under varying rotational speeds and loading torques show increasing wear and deformation at higher speeds and torques confirming the state of the art described in the literature. In addition, the time dependent deformation behaviour at different load conditions due to superposition of wear and plastic deformation could be analysed in detail.

Analyzing the Life Prediction of Spur Gear based on Vinyl Ester with Different Fibre Proportion

The gear is an essential part of every mechanical power transmission system, as well as most industrial rotating machinery. Gears may grow to dominate as the most effective mechanism for transmitting power in future machines due to their high degree of durability and compactness. The vinyl ester resin have high strength and low frictional of porous carbon material. The Vinyl ester resin is used as a reinforced material in plastic gear. In this work, Vinyl Ester and Glass fiber composite material with different proportions were equipped for strengthen cast plastic gear. The spur gear pair was used as the test gears, and the glass transition temperature and fatigue tests were used to determine the gear's life span. Finally, the composite gear has to be analyzed.

Time-resolved ex situ Raman/FT-IR spectroscopic study of structural changes in polymeric gears during operation: Towards the development of operando spectroscopic systems for polymer gears

In this study, time-resolved ex situ Raman and Fourier transform infrared (FT-IR) spectroscopy were performed to monitor structural changes in a polyamide (PA) 66 gear during operation and reveal the failure mechanisms of the material. A gear test was performed using a lab-built gear tester, which is a power-absorption type. Raman and FT-IR analyses were performed on the side gear surfaces around the root of the gear (at the side of the active flank), where a bending stress is continuously loaded during operation. The results showed that the crystallinity changed, amide related bonds were broken, trans-gauche (TG) transformation occurred, and a change in the inner stress condition of the PA66 gear occurred over time. It was concluded that these changes interact with each other during operation and are related to the failure of the PA66 gear, such as the initiation of the plastic gear degradation.

Wear and Service Life of 3-D Printed Polymeric Gears

Plastic gears are mostly used in the textile, food, and automotive industries due to their silent operation, corrosion resistance, and light and cheap advantages. Plastic gears are generally manufactured by injection molding or hobbing methods. The excess costs of the molds used to produce parts in injection molding and the problems of wastes that occur during production in hobbing lead companies to additive manufacturing, which is an alternative application. In the additive manufacturing method, the desired amount of product is produced without the problem of waste. In this study, the wear resistance of plastic spur gears produced by the Fused Deposition Modeling (FDM) method was determined theoretically. In order to determine the service life of gears, wear tests were carried out in the Forschungsstelle fur Zahnrader und Getriebebau (FZG) type test device at the same load and rotational speeds. polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PETG) thermoplastic polymer materials were used in the production of gears. When the gears rotate at the same load and rotational speeds, the most wear was observed in ABS, PLA, and PETG at the theoretically calculated wear depths. PETG is the most resistant material in terms of wear.

Comparison of Methods for Calculating the Heating of Plastic Gears

Accurate determination of heating is significantly more important for plastic gears, even in simpler applications than for steel gears. These gears are often used without lubrication or with a single, lifetime lubrication. The load capacity of materials is significantly affected by temperature, even in ordinary cases. Even today, heating is often calculated for different heating cases according to the calculation method of VDI 2545 or the modified VDI 2545, although these methods have been proven to be obsolete. Since the main direction of our research is to explore the design features of drive units equipped with small plastic gears, we tried to assess in advance, using a series of calculations, how much difference there is between the results obtained with obsolete and modern calculation methods. In this article, we present the basic characteristics of the calculation methods and compare the results obtained for some m>1 mm and m<0,5 mm gears.