scholarly journals Characterization of Surface Topography Variation in the Ultra-Precision Tool Servo-Based Diamond Cutting of 3D Microstructured Surfaces

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1448
Author(s):  
Wei Yuan ◽  
Chi-Fai Cheung
Keyword(s):  
Surface Topography ◽  
Dynamic Model ◽  
Cutting Speed ◽  
Surface Generation ◽  
Dynamic Force ◽  
Diamond Cutting ◽  
Microstructured Surfaces ◽  
Ultra Precision ◽  
Cutting System

Previous models of the relative tool-work vibration are not generalized to represent the surface generation mechanism in the ultra-precision tool servo-based diamond cutting (UTSDC) of three-dimensional (3D) microstructured surfaces. This is due to the fact that the tool-work vibration in UTSDC is no longer a steady harmonic vibration with a constant amplitude but is influenced by the tool motion along the thrust direction. In this paper, dynamic modeling of the cutting system is presented for the characterization of surface topography variation in UTSDC of a microlens array considering the tool-work vibration as an underdamped vibration. The natural frequency and damping ratio of the cutting system are determined by the data-dependent systems (DDS) method. Based on the analysis of the surface profile and cutting force signals, it is found that the tool-work vibration is significantly enhanced in the cut-in process when the cutting speed increases. The simulation results show that the proposed dynamic model can well-determine root-mean-squares RMS values of the surface primary profile and the dynamic force acting on the force sensor. The dynamic model provides insight into the formation of the surface topography variation in UTSDC of 3D microstructured surfaces, and the model might be applied in self-optimized machining systems in the future.

scholarly journals A prediction model of the surface topography due to the unbalance of the spindle system in ultra-precision fly-cutting machining

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401774714
Author(s):  
Dongju Chen ◽  
Xianxian Cui ◽  
Ri Pan ◽  
Jinwei Fan ◽  
Chenhui An
Keyword(s):  
Prediction Model ◽  
Surface Topography ◽  
Rotation Speed ◽  
Surface Generation ◽  
Machining Accuracy ◽  
Machined Surface ◽  
Spindle System ◽  
Fly Cutting ◽  
Ultra Precision ◽  
Aerostatic Spindle

In ultra-precision fly-cutting machining, the aerostatic spindle is the key component, which has significant influence on the machined surface quality. The unbalanced spindle directly affects the machining accuracy. In this article, a prediction model of machining surface topography is proposed which involves the effect of the gas film performance of spindle in microscale. With the Weierstrass function, unstable transient response of the aerostatic spindle system is derived by the motion model of the spindle, which response signal represents the surface profile in the ultra-precision machining. Meanwhile, the experiment is performed with different rotation speed of the spindle. And the effect of the unbalanced aerostatic spindle on the surface generation is discussed in time and frequency domain. The conclusion shows that the similar cyclical surface ripple of the workpiece is independent of the spindle speed, and the rotation speed of the spindle and unbalanced spindle directly affects the machining surface topography. This study is quite meaningful for deeply understanding the influence rule of spindle unbalanced error from the viewpoint of machined surface and vibration frequency.

Influencing Factors of Surface Generation in Ultra-Precision Fly Cutting

2016 ◽  
Vol 1136 ◽  
pp. 221-226
Author(s):  
Lan Zhan ◽  
Fei Hu Zhang ◽  
Chen Hui An ◽  
Zhi Peng Li
Keyword(s):  
Surface Topography ◽  
Influencing Factors ◽  
Surface Profile ◽  
Surface Generation ◽  
Cutting Machine ◽  
Fly Cutting ◽  
3D Surface ◽  
Ultra Precision ◽  
Topography Model ◽  
Great Focus

Ultra-precision fly cutting machines have long been the hardest one to compliant and induce great focus of researchers. In this paper, a surface topography model is proposed to predict the surface generation in an ultra-precision fly cutting machine. The building of surface topography model is based on the trace of the tool tip. With the 3D surface profile simulations of workpieces, several influencing factors of surface topography, especially the factors related to micro waviness error, are studied.

scholarly journals Characterization of the Friction Coefficient of Aluminum Alloy 6061 in Ultra-Precision Machining

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 336 ◽  
Author(s):  
Hailong Wang ◽  
Tao Zhang ◽  
Sujuan Wang ◽  
Suet To
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Surface Generation ◽  
Precision Machining ◽  
Diamond Cutting ◽  
Machined Surface ◽  
Friction Coefficients ◽  
Aluminum Alloy 6061 ◽  
Ultra Precision ◽  
Alloy 6061

Aluminum alloy 6061(Al6061), an Al-Mg-Si alloy, is a precipitation-hardened alloy. The generation of precipitate affects its mechanical properties, and induces a worse surface finish during diamond cutting. The friction coefficients of the tool-chip and tool-workpiece interfaces influence temperature rise, and are therefore important predictors of tool wear and surface integrity during the diamond cutting of Al6061. This study investigated the relationship between precipitate generation and the friction coefficients of Al6061. Groups of experiments were conducted to study the influence of temperature and heating time on the number of precipitates and the friction coefficients. The results show that the generation of AlFeSi particles induces cracks, scratch marks and pits on diamond-machined Al6061 and affects the cutting forces. Moreover, the variation trend of the friction coefficient of Al6061 under different heating conditions agrees well with that of the number of AlFeSi particles. This implies that, during ultra-precision machining of precipitation-hardened alloys, cutting-induced heat causes precipitates to form on the chips and machined surface, changing their material properties. This affects the tool-workpiece and tool–chip contact conditions and the mechanisms of chip formation and surface generation in ultra-precision machining.

scholarly journals Theoretical prediction and experimental verification of the unbalanced magnetic force in air bearing motor spindles

2019 ◽  
Vol 233 (12) ◽  
pp. 2330-2344 ◽  
Author(s):  
Quanhui Wu ◽  
Yazhou Sun ◽  
Wanqun Chen ◽  
Qing Wang ◽  
Guoda Chen
Keyword(s):  
Surface Topography ◽  
Surface Quality ◽  
Magnetic Force ◽  
Research Work ◽  
Diamond Turning ◽  
Surface Generation ◽  
Air Bearing ◽  
Machined Surface ◽  
Spindle Shaft ◽  
Ultra Precision

Dynamic vibrations of air bearing motor spindles have significant influence on the surface quality in ultra-precision machining. In this article, the influence of the vibration caused by the unbalanced magnetic force on the diamond turning is investigated on the basis of the theoretical and experimental method. A permanent magnet motor model (10 poles and 12 slots) is built and then simulated to gain a periodic unbalanced magnetic force. The effects of unbalanced magnetic force on the inclination of the spindle shaft is analyzed, which would affect the surface quality of the workpiece, and the surface topography of the workpiece is predicted during an unbalanced magnetic force acting on air bearing motor spindle. The theoretical analysis and experimental turning results validate that the angle between the direction of unbalanced magnetic force and the feed direction has a certain relationship with the profile of the machined surface. Also, under different turning speeds and directions, the surface topography of the machined workpiece shows a 10-cycle-per-revolution pattern, which has good agreement with the simulations of periodic unbalanced magnetic force. This research work provides a theoretical foundation for the fault diagnosis of air bearing motor spindle caused by motor rotor eccentricity and its effect on surface generation in turning.

Spindle vibration influencing form error in ultra-precision diamond machining

2016 ◽  
Vol 231 (17) ◽  
pp. 3144-3151 ◽  
Author(s):  
SJ Zhang ◽  
S To
Keyword(s):  
Surface Roughness ◽  
High Efficiency ◽  
Cutting Speed ◽  
Spindle Speed ◽  
Surface Generation ◽  
Generation Model ◽  
Form Error ◽  
Diamond Machining ◽  
Ultra Precision ◽  
Spindle Vibration

Ultra-precision diamond machining (UPDM) is widely used to manufacture high quality surface within sub-micrometric form error and nanometric surface roughness due to its high efficiency and low cost. However, in a complex UPDM process, many factors affect such sub-micrometric form error. Especially, spindle vibration produces a significant impact upon surface generation, not only influencing nanometric surface roughness, but also affecting sub-micrometric form error. In this study, a five-DOF dynamic model is established for spindle vibration in UPDM. The form error under spindle vibration is discussed with a surface generation model. The results show that (i) axial, radial, and coupled-tilting spindle vibration makes a great contribution to form error; (ii) the coupled-tilting frequencies are influenced by spindle speed; and (iii) the spindle vibration is reproduced at a machined surface to generate regular patterns consequently to cause form error, which is well identified with a focus on axial spindle vibration by face turning in UPDM. Its wavelength is linearly proportional to spindle speed and cutting radius distance, i.e. cutting speed. Significantly, the proposed models provide a possibility to predict surface roughness and form error under spindle vibration.

scholarly journals Theoretical and Experimental Investigation of Surface Topography Generation in Slow Tool Servo Ultra-Precision Machining of Freeform Surfaces

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2566 ◽  
Author(s):  
Duo Li ◽  
Zheng Qiao ◽  
Karl Walton ◽  
Yutao Liu ◽  
Jiadai Xue ◽  
...  
Keyword(s):  
Surface Topography ◽  
Tool Path ◽  
Tool Path Generation ◽  
Surface Generation ◽  
Precision Machining ◽  
Path Generation ◽  
Freeform Surfaces ◽  
Ultra Precision ◽  
Slow Tool Servo ◽  
Radius Compensation

Freeform surfaces are featured with superior optical and physical properties and are widely adopted in advanced optical systems. Slow tool servo (STS) ultra-precision machining is an enabling manufacturing technology for fabrication of non-rotationally symmetric surfaces. This work presents a theoretical and experimental study of surface topography generation in STS machining of freeform surfaces. To achieve the nanometric surface topography, a systematic approach for tool path generation was investigated, including tool path planning, tool geometry selection, and tool radius compensation. The tool radius compensation is performed only in one direction to ensure no high frequency motion is imposed on the non-dynamic axis. The development of the surface generation simulation allows the prediction of the surface topography under various tool and machining variables. Furthermore, it provides an important means for better understanding the surface generation mechanism without the need for costly trial and error tests. Machining and measurement experiments of a sinusoidal grid and microlens array sample validated the proposed tool path generation and demonstrated the effectiveness of the STS machining process to fabricate freeform surfaces with nanometric topography. The measurement results also show a uniform topography distribution over the entire surface and agree well with the simulated results.

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