A New Experimental Approach for Measuring Friction Coefficients of Threaded Fasteners Focusing on the Repetition of Tightening Operation and Surface Roughness

2013 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Masataka Nomura ◽  
Hiromu Kawabayashi
Keyword(s):  
Surface Roughness ◽  
Experimental Approach ◽  
High Accuracy ◽  
Strain Gages ◽  
Simple Test ◽  
Friction Coefficients ◽  
Threaded Fasteners ◽  
Loaded Surface ◽  
Experimental Errors ◽  
Easy Operation

Torque method is widely used when tightening threaded fasteners. Although it has a great advantage of easy operation, the scatter of bolt preloads inevitably occurs due to the scatter of friction coefficients. Friction coefficients on the contact surfaces are affected by various factors such as joint materials, surface roughness, tightening speed, etc. To evaluate the effects of those factors with high accuracy, experimental errors must be suppressed as low as possible. In this study, a new simple test equipment for measuring the friction coefficients is designed, in which the strain gages are attached to the equipment to eliminate the experimental errors caused by the gages being attached to each test specimen. Using the equipment, friction coefficients on the thread surface and nut loaded surface are measured separately. Experimental results show that the surface roughness has a smaller effect when using threaded fasteners made of stainless steel than the case of carbon steel fasteners. As for the repetition of tightening operations, it is found that the removal of metal power, which is generated by the galling between the mating surfaces, is effective for reducing the scatter of friction coefficients.

Surface damage characterization of photodegraded low-density polyethylene by means of friction measurements

2019 ◽  
Vol 39 (9) ◽  
pp. 805-812
Author(s):  
Toshio Igarashi ◽  
Soichiro Ohno ◽  
Sayaka Oda ◽  
Satoru Hirosawa ◽  
Yusuke Hiejima ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Irradiation Time ◽  
Polymeric Materials ◽  
Optical Measurements ◽  
Low Density Polyethylene ◽  
Mean Deviation ◽  
Low Density ◽  
Friction Coefficients ◽  
Brittle Transition ◽  
Friction Measurements

Abstract Friction measurements have been carried out to characterize surface damages during photodegradation of low-density polyethylene. The average and mean deviation of the friction coefficients increase with the irradiation time in the early stage of photodegradation processes, indicating the increase in the surface roughness, whereas the mechanical properties remain essentially unchanged. In the following stage, where the ductile-brittle transition takes place, the mean deviation of the friction coefficients shows an appreciable decrease with maintaining almost constant average values, suggesting that the surface becomes more homogeneous. Beyond the ductile-brittle transition, both of the average and mean deviation of the friction coefficients gradually increase with the irradiation time, indicating further enhancement of surface roughness, followed by formation of surface cracks. The soundness of the friction measurements is confirmed by comparing with optical measurements of the surface roughness, and it is suggested that the present method gives a convenient and sensitive method of detection for degradation in polymeric materials.

scholarly journals Surface Roughness, Hydrophilicity and Encapsulation Efficiency of Gentamicin Loaded Surface Engineered PLA Microspheres

2018 ◽  
Vol 1082 ◽  
pp. 012068
Author(s):  
Tran Thi Thu Trang ◽  
Mariatti Jaafar ◽  
Badrul Hisham Yahaya ◽  
Masakazu Kawashita ◽  
Nguyen Xuan Thanh Tram ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Encapsulation Efficiency ◽  
Loaded Surface

Experimental Evaluation of Surface Roughness in Orthogonal Micro-Milling Processes

2012 ◽  
Vol 217-219 ◽  
pp. 1912-1916
Author(s):  
Ji Hua Wu
Keyword(s):  
Surface Roughness ◽  
Feed Rate ◽  
Experimental Approach ◽  
Critical Role ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Micro Milling ◽  
Surface Model ◽  
Material Grain Size

Surface roughness plays a critical role in evaluating and measuring the surface quality of a machined product. Two workpiece materials have been investigated by experimental approach in order to gain a better understanding of their influence on the obtained surface roughness in the micro-milling processes. The experimental results show that: surface topography is completely different for different materials at the same cutting speed and feed rate; surface roughness increases with an increase of material grain size. Surface roughness decreases to a lowest value, and then increases with an increase of the feed rate. A new surface model to illustrate the influence of material and uncut chip thickness was developed. The model has been experimentally validated and shows more promising results than Weule’s model.

A Digital Near Net Shape Manufacturing Propeller with Complex Surface

2011 ◽  
Vol 201-203 ◽  
pp. 117-120
Author(s):  
Zhong Fei Jiao ◽  
Shan Yao ◽  
Shu Ming Zhao ◽  
Feng Zeng ◽  
Di Wu
Keyword(s):  
Surface Roughness ◽  
Rapid Prototyping ◽  
Dimensional Accuracy ◽  
Casting Process ◽  
Complex Surface ◽  
High Accuracy ◽  
Parametric Modeling ◽  
Marine Propeller ◽  
3D Cad ◽  
Near Net Shape

An integrated digital routine is applied in the near net shape manufacturing of marine propeller. Firstly, the 3D CAD file of propeller is created by parametric modeling. Secondly, the propeller casting process is simulated using CAE software, through which an optimized casting scheme is obtained. Thirdly, fabricates the mold using laser rapid prototyping and cast the metal propeller. Finally, evaluate the casting precision performance. CAD, CAE and CAM are integrated in this process. The dimensional accuracy of the final piece is controlled within 1mm and its surface roughness achieves Ra 6.3μm. The result shows that the pattern-less casting of propeller can be achieved by this method, reducing cost and performing high accuracy.

Robustness of polyisobutylene for friction coefficients between bearing surfaces of bolted joints

2019 ◽  
Vol 234 (1) ◽  
pp. 50-62
Author(s):  
Shinji Hashimura ◽  
Toshiumi Miki ◽  
Takefumi Otsu ◽  
Kyoichi Komatsu ◽  
Shota Inoue ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Surface Hardness ◽  
Bolted Joints ◽  
Friction Coefficients ◽  
Clamp Force

In bolted joints, clamp force must be accurately controlled to secure their reliability. However, the clamp force varies widely in each tightening because friction coefficients at thread surfaces and bearing surfaces vary in each tightening due to lubricants, configuration error of bolts, surface roughness, and surface hardness, among other things. In this study, we investigated the robustness of polyisobutylene and ISO VG46 machine oil during the tightening process for several parameters of tightening conditions. We especially focused on variations of the friction coefficient between bearing surfaces at an appropriate target clamp force of M8 bolt/nut assemblies and change rates of the friction coefficients from the middle to the end of the appropriate target clamp force. Results showed that the friction coefficients at the target clamp force varied widely if ISO VG46 machine oil was used as a lubricant. In contrast, the variations of the friction coefficients in which polyisobutylene was used for tightening were small. Results also showed that the friction coefficients invariably decreased about 20% from the middle to the end of the target clamp force if ISO VG46 machine oil was used for the lubricant. However, if polyisobutylene was used, the friction coefficients were almost constant for all tightening instances.

Fuzzy logic-based modeling and analysis of surface roughness, electrostatic charge, and material removal rate in ultrahigh precision diamond turning of rigid contact lens polymer

2019 ◽  
pp. 089270571985060
Author(s):  
Muhammad Mukhtar Liman ◽  
Khaled Abou-El-Hossein ◽  
Lukman Niyi Abdulkadir
Keyword(s):  
Surface Roughness ◽  
Fuzzy Logic ◽  
Material Removal Rate ◽  
Contact Lens ◽  
Material Removal ◽  
Removal Rate ◽  
Electrostatic Charge ◽  
High Accuracy ◽  
Diamond Turning ◽  
Optical Manufacturing

Due to increasing demand for high accuracy and high-quality surface finish in optical industry, contact lens manufacturing requires reliable models for predicting surface roughness (Ra) which plays a very important role in the optical manufacturing industry. In this study, a Nanoform 250 ultra-grind turning machine was used for machining, while cutting speed, feed rate, and the depth of cut (with values selected to cover a wide range based on the literature) were considered as the machining parameters for a diamond turned rigid polymethylmethacrylate (PMMA) contact lens polymer. Turning experiments were designed and conducted according to Box–Behnken design which is a response surface methodology technique. Fuzzy logic-based artificial intelligence method was employed to develop an electrostatic charge (ESC), Ra, and material removal rate (MRR) prediction models. The accuracy and predictive ability of the fuzzy logic model was then judged by considering an average percentage error between experimental values and fuzzy logic predictions. Further, a comparative evaluation of experiments and fuzzy logic approach showed that the average errors of ESC, Ra, and MRR using fuzzy logic system were in tandem with experimental results. Hence, the developed fuzzy logic rules can be effectively utilized to predict the ESC, Ra, and MRR of a rigid PMMA contact lens polymers in automated optical manufacturing environments for high accuracy and computational cost.

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