Nylon Gears Research Articles

Numerical investigation on meshing temperature of multicomponent nylon gears by incorporating viscoelasticity

This study concerns a numerical analysis of the meshing temperature for a multicomponent nylon gear by incorporating typical viscoelastic responses of polymers. Firstly, the generalized Maxwell model parameters were calibrated by the dynamic mechanical analysis to capture the viscoelasticity of polyamide 66. Next, the finite element model predicting the meshing temperature was established, including the heat generation analysis model, which calculates the generation of the frictional and hysteretic heat, and the heat propagation analysis model, which simulates the heat transmission. Different material models were used for polyamide 66 to investigate the influences of temperature dependence, strain rate dependence, and hysteretic effect. The effect of the iteration sequence on the meshing temperature calculation was also analyzed, i.e., how the heat generation should be updated as the loading cycles increase. A reasonable iteration scheme was determined by balancing the computational precision and consumption. It is noteworthy that the evolution of the ambient temperature around the gear and the worm within the housing was also considered. Finally, the accuracy of such meshing temperature analysis was validated on a self-developed gear test rig, in terms of the peak temperature evolution on the gear side surface. The experimental results and the simulation with the ambient temperature correction match well and the maximum error is 5 °C.

Failure analysis of nylon gears made by additive manufacturing

Additive manufacturing enables fast manufacturing of polymer gears directly from a 3D model. Failed polymer gears can be replaced easily and quickly using many different materials. Mechanical and thermal characteristic of gears manufactured using additive manufacturing are mostly dependent on selected manufacturing parameters and material. In this research, the influence of the most important manufacturing parameter (infill percentage) on failure types and service life of additive manufactured nylon gears is experimentally investigated. The experimental tests were carried out using a custom-made gear testing device. Samples with 20, 40, 60, 80 and 100% of infill volume were tested. Infill type, shell thickness, and manufacturing speed were the same for all samples. Service life of gears was tested and failure types were characterized.

Model-based fault diagnosis of sliding gates electro-mechanical actuators transmission components with motor-side measurements

This paper presents a model-based fault detection and isolation scheme for the transmission components of Electro-Mechanical Actuators, applied to the actuation of sliding gates. The most important failures are investigated by a Failure Mode, Effects, and Criticality Analysis procedure. Following Failure Mode, Effects, and Criticality Analysis, the components selected for the development of the diagnostic algorithm are the nylon gear and pinion of the Electro-Mechanical Actuator, and the rack of the gate. The proposed diagnostic algorithm is able to isolate two out of the three types of faults. The overall procedure is validated by experimental results.

Vibration analysis of nylon gear box utilizing statistical method

Gears are important element in a variety of industrial applications such as medical and automotive sectors. In the medical field it is used in surgical instruments, Biopsy instrumentation and Dental implant products. In automotive sectors like Electrical Throttle Controls, Steering Systems, Instrument Clusters, Window and Door Latch systems. Though the plastic gears have less heat dissipation, high wear resistance and self-lubrication properties, there may be defects in nylon gears in runtime applications. The defects include surface fatigue like pitting, scuffing, scratching and some common defects like flash, warping, bubbles etc.The gear defects are often identified under switch off condition and gear are checked. There are defect testing methods like image processing. In this work the defects were identified when the system is in running condition, by analysing the vibration signals obtained from the system under varying load and speed conditions. Gears are designed based on the parameters like module, pitch circle diameter, no of teeth and bending load capacity.In this work, the experimental setup is fabricated for testing the gears at three different sets of speeds. By varying the speed of transmission between two shafts both in loading and unloading conditions, the sound signals are acquired using sound sensor and sound signals are processed using MATLAB. The time-domain signal and frequency domain signals are used to detect the failure in nylon gear. Using the parameters like kurtosis, RMS, variance and standard deviation value the good gears and defective gears are compared. By using this method the defects in nylon gears can be identified easily.

Tribological Characteristics of Natural Fiber Reinforced Polyester Hybrid Composites

In order to investigate the wear behavior and tooth damage of Madar and Bauhinia Racemosa fibers reinforced polyester, the composite gears were fabricated with varying the fiber weight percentages of 5%, 10%, 15% and 20%. This paper explores the rolling and sliding of the composite gears running against nylon gear with a simplified method of analyzing and understanding the wear and tooth damage. Tests were conducted without external lubrication over a range of loads 4Nm, 8Nm,12Nm and 16Nm using a gear test rig. The test results of composite gears are compared with unreinforced polyester gear (URPE). It was found that the surface temperature was the primary factor affecting the wear rate and an initial relationship between gear surface temperature and load capacity. This composite can be useful for automobile and industrial applications.

The wear behavior and service life of Madar and Bauhinia Racemosa reinforced polyester hybrid composites for gear applications

Abstract In order to investigate the wear behavior and service life of Madar and Bauhinia Racemosa fibers reinforced polyester, the composite gears were fabricated with varying the fiber weight percentages of 5%, 10%, 15% and 20%. This paper examines the rolling and sliding of the composite gears running against nylon gear with a simplified method of analysing and understanding the wear rate and tooth damage. Tests were conducted without external lubrication over a range of loads using a gear test rig. The test results of composite gears are compared with unreinforced polyester gear (URPE). The extremely interesting investigation from the experimental work is the drastically different wear behavior when running composite gears against nylon gears, specifically the low wear rate when compared with URPE. It was found that the surface temperature was the primary factor affecting the wear rate and an initial relationship between gear surface temperature and load capacity.

Effects of lapping using nylon gear tool on endurance limit of shot-peened gas-carburized gears

Effects of lapping using nylon gear tool on endurance limit of shot-peened gas-carburized gears

マシニングセンタを用いて抽出した竹繊維のみの成形歯車のかみあいモニターと考察

A plastic gear has the advantages that it is light and can be used without any lubricant, and the disadvantages that its strength is low and that it has a large environmental impact. Therefore, the development of a new gear that maintains the advantages while negating the disadvantages has been proposed. The development of sustainable and reproducible natural materials is especially desired in order to address environmental problems. In this study, a method was therefore devised to extract high quality and highly precise bamboo fibers using a machining center. The hot press method was then used to produce a spur gear, which is a machine element with a complicated shape. Therefore, the present paper describes characteristics of the bamboo fiber gears investigated in some experiments. The results of a strength test showed that the bamboo fiber gear can be used as an alternative to the Mc nylon gear. The results of a meshing test showed that the teeth of a bamboo fiber gear underwent transformation because of the meshing load. In addition, we calculated travel value of meshing point by teeth deformation and compared experimental value of travel value with calculated value. Results show that the experimental deformation value is greater than the calculated value.

Strength Evaluation and Failure Prediction of Short Carbon Fiber Reinforced Nylon Spur Gears by Finite Element Modeling

In this paper, short carbon fiber reinforced nylon spur gear pairs, and steel and unreinforced nylon spur gear pairs have been selected for study and comparison. A 3D finite element model was developed to simulate the multi-axial stress–strain behaviors of the gear tooth. Failure prediction has been conducted based on the different failure criteria, including Tsai-Wu criterion. The tooth roots, where has stress concentration and the potential for failure, have been carefully investigated. The modeling results show that the short carbon fiber reinforced nylon gear fabricated by properly controlled injection molding processes can provide higher strength and better performance.

An investigation on the wear behaviour of dissimilar polymer gear engagements

Following an interesting observation reported in the Wear of Materials 2009 by the present authors [1], the current paper will present an extensive investigation of dissimilar polymer gear contact, friction and wear behaviour. The unique polymer gear test rig employed will be briefly introduced. The most interesting observation from the experimental work is the significantly different wear behaviour when running acetal against nylon gears, especially the low wear rate when the acetal gear is the driver. To understand the interesting behaviour, detailed modelling work has been carried out to investigate the mechanisms of dissimilar gear engagements as well as which one is the driver. The advanced non-linear finite element method has been employed to simulate the gear tooth contact. It has been found that the gear contact force during the access process is higher than that in the recess process. Further work has been carried out on the high performance PEEK gear contacts, i.e. PEEK against steel, steel against PEEK and PEEK against PEEK. To improve the high friction and wear of the gear tip, a micron geometry modification method, tip relief, has been employed and significant frictional contact force reduction has been achieved.

Development of the Center-Less Gear Lapping Machine and the Lapped Gears

The objective of this present study is to develop a center-less gear lapping machine that can simultaneously smooth all of tooth flanks of a steel gear to a maximum peak-valley height ( Rz ) of less than 1 µm in a short time without fixing the gear to a shaft. A work gear meshes with two lap gears as crossed helical gears and is supported by a guide gear during the lapping. The two lap gears and the guide gear are nylon gears. Lapping slurry which contains abrasive grains is supplied to the meshing teeth. The present paper presents the mechanism of the center-less lapping process and the structure of the lapping machine designed and manufactured by the present authors. The behavior and amount of removed mass of the work gear are investigated during the lapping process. In addition, the work gears lapped using the proposed machine are evaluated with respect to the tooth roughness and the accuracy of the tooth profile, tooth trace, and pitch. Nylon lap gears are also tested to investigate their lives.

Friction and wear behaviour of acetal and nylon gears

The current paper will present an extensive investigation of polymer gear (acetal and nylon) friction and wear behaviour. First, a unique test method for polymer gear wear will be described in brief and later used in the extensive investigation of acetal and nylon gear wear. Initial tests were performed using acetal pinions with acetal gears, and nylon pinions with nylon gears, with further investigation carried out using dissimilar polymer gears. In this case the driver and driven effects on the gear wear behaviour was also considered when dissimilar materials were used. For acetal against acetal gears, it was found that the acetal gear wear rate increased dramatically when the load reached a critical value for a specific geometry and the gear surface showed slow wear, with a low specific wear rate if the gear was loaded below this critical value. It was found that the surface temperature was the dominant factor influencing the wear rate and an initial relationship between gear surface temperature and gear load capacity has been established and further developed. Experimental investigation on nylon gears was also carried out and different failures have been found compared to acetal gears, such as gear root and pitch fractures. The most interesting observation from the experimental work is the significant difference in wear behaviour when running acteal against nylon gears, especially the low wear rate when acetal is used as the driver gear.

Durability improvement method for plastic spur gears

An experimental investigation of power-transmission plastic spur gears was performed by inspecting both the characteristics of wear and durability, and a durability improvement method is proposed that either drills an internal hole or inserts a steel-pin in the internal hole of the gear tooth, and this proposed method was verified. In the case of acetal gears, the amount of wear was observed to increase with the development of plastic deformation, and an increase in tooth stiffness occurred due to the brittle material property of acetal. On the other hand, in the case of nylon gears, the proposed method was shown to reduce the tooth temperature compared to the original gear, thus reducing the amount of wear and prolonging service life. Hence, the proposed method was proven to be practically applicable to plastic gears made from soft polymers that show visco-elastic properties such as nylon.

Finishing Process of Hobbed Gear using a Nylon Lap and Its Effects

The objective of this research is to develop a new lapping process which can efficiently make tooth flanks of hardened steel gears smooth as a mirror. This lapping process is carried out on the trial-made gear lapping machine using a nylon helical gear as a lap. In this paper the lapping process accompanied by vibration of the nylon gear was attempted to improve the tooth roughness and the accuracy of hobbed gears. Micro hardness, micro structure and residual stress on the tooth flank of lapped gears were also examined. As the results, it was found that the vibration of the nylon gear increases the removal rate and reduces more efficiently tooth flank roughness of work gears. And the running noise and the load carrying capacity of lapped gears were investigated. The running noise and the load carrying capacity of lapped gears were improved.

플라스틱스퍼기어의 내구성향상에 관한 실험연구

Operating test of power-transmisson plastic spur gears were performed inspecting both characteristics of friction-wear and endurance, and suggesting endurance improvement method that either drills internal holes of tooth or inserts metallic pin in the internal hole of tooth and verifying this newly-provided method. In case of acetal gears, amount of friction-wear is observed to increase by development of plastic deformation and increse by bevelopment of plastic deformation and increase of tooth stiffness due to brittle material property of acetal. To the contrary, in case of nylon gears, suggested method is shown to drop down the tooth temperature for about 3~10 ℃ than original gear, thus amount of wear is reduced by over 30% and operating life prolonged by more than 200%. Hence, suggested method is proved to be practically applicable to the plastic gears made by soft polymers such as Nylon.

Finishing of High-Precision Gears with a Nylon Lap.

This research aims at developing a new lapping process which can make efficiently tooth flanks of hardened steel gears smooth as a mirror. The lapping process is carried out using a nylon helical gear and a simple mechanical device. This paper shows causes of increases of tooth profile errors in this lapping and proposes how to prevent them according to results of lapping tests with many ground high-precision gears under various conditions. It is concluded that it is important to carry out the lapping for a short time using a nylon gear which has a large helix angle and high-teeth under a condition of high-speed revolution and light load in order to prevent increases of tooth profile errors.

Modelling of spur gear mesh stiffness and static transmission error

A modified transmission error (TE) model is introduced for analysing the effects on the transmission error of variation of tooth body stiffness with load application point, and a simulation program for transmission error computation with varying stiffness has been developed. In order to obtain the case where the tooth deflection component is the dominant source of the TE, nylon gears were used in this study. All the simulation results have been compared with the measured transmission errors from a single-stage gearbox. Even though carried out on low precision gears, the validity of the model for the more flexible nylon gears indicates that the model can be used for analysing the transmission error of high-precision gear sets.

Basic Characteristics of Plastic Gears Lubricated with Water

Recently, plastic gears have been used in water, but depending on the kind of plastic, there are some gears which show a great deal of wear when they are used in water. However, it is important to note that in water or in places where moisture exists, water functions as a lubricant, and wear decreases as compared with the case without lubrication. To date, some reports have addressed this phenomenon but few have presented data on the design of plastic gears for use in water. In light of this situation, in this study, nylon gears and polyacetal gears, which are widely used plastic gears, were operated in water and with a small number of water drops, and various characteristics such as the wear of the teeth, the change in the tooth profile, the tooth surface roughness and so on, due to the difference in the quantity of bathing water were examined.

Basic Characteristics of Plastic Gears Lubricated with Water.

Recently, plastic gears have become to be used also in water, but according to the kinds of plastics, there are some which show a great deal of wear when they are used in water. However, it is considered also that in water or in the place where moisture exists, water performs lubricating action, and wear decreases as compared with the case without lubricathon. At present, the report which can answer this problem, and can become the design data for the plastic gears lubricated with water is scarcely found. Due to the situation like this, in this study, the nylon gears and polyacetal gears which have been used widely as plastic gears were operated in water and with small quantity of water drops, and the various characteristics such as the wear of the teeth, the change of the tooth profile, the roughness of the tooth surfaces and so on due to the difference of the bathing water quantity were examined.

A study on development of low noise gears. Silencing effect and operation characteristics of nylon gears filled with plasticizers.

Recently, plastic gears with lower noise have been demanded for assembly in sound apparatuses. For this purpose, the use of plastics filled with plasticizers for gears has been attempted. when plasticizers are filled into plastics, the deformability increases; on the other hand, the strength and wear resistance decrease. Accordingly, there are some people who doubt their practicality. Therefore, in this study, gears were made of material made by filling more than lO% plasticizers into nylon, and the effect of silencing was confirmed, and the basic characteristics of gears such as the wear of teeth and the change of the tooth profile were experimentally examined.