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Optical Instrument Structural Design
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
A decrease in the friction coefficient with velocity causes stick-slip. As the component velocity increases, the resisting friction force decreases, causing acceleration. As the component continues to accelerate, the exciting force decreases; the moving component catches up with the force. When the relative exciting force becomes zero, the component no longer accelerates and stops abruptly. Then, the entire process starts again, leading to discontinuous oscillating motion or stick-slip. Stick-slip is avoided by the use of materials with friction coefficients that increase with velocity, providing damping to the self-excited motion. One example of such a material is Teflon. The use of Teflon is common, not only to decrease friction coefficients but also to minimize stick-slip (Nakazawa, 1994).
Bearings, Slides, Guides, Ways, Gears, Cylinders, Couplings, Chains, Wire Ropes
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
A phenomenon known as stick-slip can be encountered in the motion of slides and ways. If the static coefficient of friction of the lubricant is greater than the dynamic coefficient, more force will be required to start the slide from rest than will be required to maintain it in motion after it has started. There is always some amount of free play in the feed mechanism, so when force is applied to start the slide in motion, it will initially resist. When the force becomes high enough, the slide will begin to move. As soon as motion begins, the force required to maintain motion decreases, so the slide will jump ahead until the free play in the feed mechanism is taken up. At low traverse speeds, this can be a continuous process, producing chatter marks on the workpiece. With cross slides, stick-slip effects can make it extremely difficult to set feed depths accurately. Stick-slip effects can be overcome with additives that reduce the static coefficient of friction to a value equal to or less than the dynamic coefficient.
Design and Construction of Magnetic Storage Devices
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Hirofumi Kondo, Hiroshi Takino, Hiroyuki Osaki, Norio Saito, Hiroshi Kano
There are some hypotheses for the mechanism of the adsorbed water behavior. “Meniscus theory” is the macroscopic hypothesis that the adsorbed water behaves like a liquid (McFarlane and Tabor, 1950), and the “interface layer of water theory” is a microscopic hypothesis that the adsorbed water is treated as uniformly arranged and layered molecules (Uedaira and Ousaka, 1989). In general, thick adsorbed water or an excessive amount of lubricant increases the static friction coefficient but keeps the kinetic friction coefficient small. The increased value of the difference between the static friction coefficient and the kinetic friction coefficient will cause stick-slip phenomenon. The disk could be damaged by the head clash that is caused by stick-slip during CSS mode.
Water-Lubricated Stern Bearing Rubber Layer Construction and Material Parameters: Effects on Frictional Vibration Based on Computer Vision
Published in Tribology Transactions, 2021
Xincong Zhou, Fuming Kuang, Jian Huang, Xueshen Liu, Konstantinos Gryllias
The vibration and noise signals shown in Fig. 10 are the results of frictional vibration, and the image signal, which resulted from the frictional vibration, which will be discussed next. During operation, the friction pair often experiences a phenomenon that is referred to as stick–slip behavior. This phenomenon is shown in Fig. 12, where the first row of signals is the displacement of the fixture of the rubber blocks with different hardness values, the second row is the displacement of the rubber blocks, and the third row is the relative displacement between the rubber block and the fixture, which can be referred to as the deformation of the rubber. It is worth noting that when the rubber hardness was 65 A, the fixture holding the rubber block hardly moved during frictional vibration. When the hardness increased, the displacement of the rubber block and the fixture increased significantly. In addition, based on the displacement data of the rubber in the second line in Fig. 12, it can be seen that as the hardness increased, the amplitude and the number of small fluctuations gradually decreased. However, the deformation data in the third row show a gradually decrease as the hardness of the rubber increased.