Effects of the Tool Angles on the Machined Surface Quality of KDP Crystal in Diamond Turning

2007 ◽  
Vol 364-366 ◽  
pp. 297-301 ◽  
Author(s):  
Jing He Wang ◽  
Ming Jun Chen ◽  
Shen Dong ◽  
Shi Qian Wang
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Rake Angle ◽  
Diamond Turning ◽  
Precision Machining ◽  
Machined Surface ◽  
Kdp Crystal ◽  
Factors Affecting ◽  
Ultra Precision ◽  
Back Angle

In the ultra-precision machining of KDP crystal, there are many factors affecting the surface quality[1-3]. The experiments show that the rake angle and back angle of the tool have significant effects on machined surface roughness. Therefore, an efficient way to improve the surface roughness is to select a proper negative rake angle. In this study, the ANSYS static analysis method was employed to analyze the stress field distribution within the whole cutting region. A finite element simulation model was set up to calculate the residual stresses variation with tool’s angles, which can be considered to select optimal rake and back angles in the ultra-precision machining of KDP crystal. Results show that the optimal tool rake angle and back angle are -49° and 7°, respectively. Finally, by using different tool angles to process KDP crystal and utilizing AFM to analyze the surface roughness, it can be found that the measurement results agree well with what are deduced from theoretical calculation.

Characterization of Cutting-Induced Heat Generation in Ultra-Precision Milling of Aluminium Alloy 6061

2013 ◽  
Vol 552 ◽  
pp. 201-206
Author(s):  
Su Juan Wang ◽  
Suet To ◽  
Xin Du Chen
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Heat Generation ◽  
Feed Rate ◽  
Dimensional Accuracy ◽  
Precision Machining ◽  
Machined Surface ◽  
Single Crystal Diamond ◽  
Ultra Precision ◽  
Alloy 6061

The technology of ultra-precision machining with single crystal diamond tool produces advanced components with higher dimensional accuracy and better surface quality. The cutting-induced heat results in high temperature and stress at the chip-tool and tool-workpiece interfaces therefore affects the materials and the cutting tool as well as the surface quality. In the ultra-precision machining of al6061, the cutting-induced heat generates precipitates on the machined surface and those precipitates induce imperfections on the machined surface. This paper uses the time-temperature-precipitation characteristics of aluminum alloy 6061 (al6061) to investigate the effect of feed rate on the cutting-induced heat generation in ultra-precision multi-axis milling process. The effect of feed rate and feed direction on the generation of precipitates and surface roughness in ultra-precision raster milling (UPRM) is studied. Experimental results show that heat generation in horizontal cutting is less than that in vertical cutting and a larger feed rate generates more heat on the machined workpiece. A smaller feed rate produces a better surface finish and under a larger feed rate, scratch marks are produced by the generated precipitates and increase surface roughness.

A Study of Factors Affecting Surface Quality in Ultra-Precision Raster Milling

2007 ◽  
Vol 339 ◽  
pp. 400-406 ◽  
Author(s):  
M.N. Cheng ◽  
Chi Fai Cheung ◽  
Wing Bun Lee ◽  
Sandy To
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Dynamic Characteristics ◽  
Diamond Turning ◽  
Factors Affecting ◽  
Cutting Geometry ◽  
Milled Surface ◽  
Ultra Precision ◽  
Process Factors

Ultra-precision raster milling is an emerging manufacturing technology for the fabrication of high precision and high quality components with a surface roughness of less than 10 nm and a form error of less than 0.2 μm without the need for any subsequent post polishing. Surface quality of a raster milled surface is affected by process factors and material factors, respectively. The process factors involve cutting conditions, cutting strategies, and relative vibration between the tool and the workpiece which are related to the cutting geometry and the dynamic characteristics of the cutting process. The material factors considered are material property and swelling of the work materials. Due to different cutting mechanics, the process factors affecting the surface quality are more complicated, as compared with ultra-precision diamond turning, such as swing distance and step distance. This paper presents an experimental investigation of the distinctive process factors affecting the surface roughness in ultra-precision multi-axis raster milling. Experimental results indicate that the influence due to the process factors can be minimized through a proper selection of operational settings and better control of dynamic characteristics of the machine.

Freeform machining of ophthalmic toric lens mould using fast tool servo-assisted ultra-precision diamond turning process

2020 ◽  
pp. 251659842093974
Author(s):  
Ishan Anand Singh ◽  
Gopi Krishna S. ◽  
T. Narendra Reddy ◽  
Prakash Vinod
Keyword(s):  
Surface Roughness ◽  
Single Point ◽  
Measurement Data ◽  
Surface Profile ◽  
Diamond Turning ◽  
Fast Tool Servo ◽  
Toric Surface ◽  
Machined Surface ◽  
Ultra Precision ◽  
A Minor

This research aims to establish a methodology for machining of toric lenses, using fast tool servo-assisted single point diamond turning and to assess the generated surface for its characteristics. Using the established mathematical model, toric surface is explained to understand the geometry and to generate the parameters required for fast tool servo machining. A toric surface with a major diameter of 18.93 mm and a minor diameter of 15.12 mm has been cut on the intelligent ultra-precision turning machine (iUPTM). The surface profile and surface roughness were measured. After analysing the measurement data of the machined surface, on two perpendicular axes of the toric lens, form accuracy of 0.49 µm peak-to-valley (PV), and surface roughness of 12 nm in Ra, 4–8 nm in Sa are obtained. From the experimental results obtained, it can be concluded that the proposed method is a reasonable alternative for manufacturing toric lens mould.

Experimental Study of the Light Scattering Induced by the Surface Roughness of the Ultraprecision Machined Workpiece

2010 ◽  
Vol 143-144 ◽  
pp. 1091-1096
Author(s):  
Chun Der Cheng ◽  
Hsi Hsun Tsai ◽  
Hui Ping Feng
Keyword(s):  
Surface Roughness ◽  
Light Scattering ◽  
Measurement Technique ◽  
Precision Machining ◽  
Diode Array ◽  
Machined Surface ◽  
Tool Marks ◽  
Scattering Effect ◽  
Photo Diode ◽  
Ultra Precision

An in-situ measurement technique of the surface roughness of ultra-precision machining by optical characteristic effects is fundamental thanks to the probe-less which would avoid the contact damage on the surface. Since the plastic lens molding reprints the roughness from the mould core fabricated by machining, the tool marks induce the poor surface of the plastic lens. By a laser with a short wavelength of He-Ne of 632 nanometers, the machined surface would reflect the input light. Several samples with different surface roughness of the aluminum by varying the feed rate of the ultra-precision machining are used to be measured by the He-Ne laser. The 1 x 16 photo-diode array with the pitch of 2.0 mm is constructed to measure the distribution of the optical scattering effect under the light source of He-Ne laser. Results show that the higher surface roughness gives a more expanse distribution of the light scattering. Besides, the BSDF of the machined surface is proportional to roughness. Using the ratio of the main and side measuring channels of the photo-diode array would give a suitable approach to construct the relationship between the light scattering and surface roughness. Therefore, the laser and the photodiode array would predict well the roughness of the ultra-precision machined surfaces of aluminum. The on-line measurement technique for the roughness by reflected light scattering effect from the ultra-precision machined surface is constructed nice in this study.

Study on Ultra-Precise Machining of CLBO Crystal

2006 ◽  
Vol 304-305 ◽  
pp. 398-402 ◽  
Author(s):  
Xun Lv ◽  
Ju Long Yuan ◽  
Yong Dai ◽  
Jia Jin Zheng ◽  
Zhao Zhong Zhou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Crystal Surface ◽  
Technical Problem ◽  
Damage Threshold ◽  
Laser Wavelength ◽  
Precision Machining ◽  
Lithium Borate ◽  
Fundamental Laser ◽  
Ultra Precision

Cesium Lithium Borate (CsLiB6O10 or CLBO) is the most effective non-linear crystal which generates ultraviolet harmonics of the Nd:YAG fundamental laser wavelength. In order to enhance the damage threshold, low CLBO surface roughness, by ultra-precision machining, is needed. Because the CLBO crystal has easy hydroscopic reaction and micro scratches in machining, ultra-precise machining of the CLBO crystal is a difficult technical problem. In this paper, the new lapping slurry and polishing slurry are introduced. And the deliquescence degree of CLBO is fallen to lowest. A new working technology is also adopted. After rough polishing, the concentration of ultra-precision polishing slurry is increased properly. So does the ultra-precision polishing speed, and the wiping speed is faster than the deliquescence speed. The CLBO crystal surface roughness can achieve 1nm and keep the surface quality well.

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.

Effects of Axial Spindle Vibration on Surface Generation in Ultra-Precision Diamond Turning

2016 ◽  
Vol 679 ◽  
pp. 67-71
Author(s):  
Shao Jian Zhang ◽  
Suet To
Keyword(s):  
Surface Quality ◽  
Crucial Role ◽  
Diamond Turning ◽  
Surface Generation ◽  
Simplified Model ◽  
Machined Surface ◽  
Proposed Model ◽  
Ultra Precision ◽  
Spindle Vibration ◽  
Mass Spring

In ultra-precision diamond turning (UPDT), axial spindle vibration (ASP) plays a crucial role influencing nanometric surface quality. In this study, a simplified model for ASP is proposed to study its effects on surface generation in UPDT as the spindle is idealized as a mass-spring-damper system. Significantly, the model successfully explains that ASP induces radial patterns at a machined surface. More importantly, this proposed model can be employed to easily predict and understand the effects of ASP on surface generation in UPDT.

Machined Surface Quality Improvement Measures Affecting Factors and Research

2014 ◽  
Vol 496-500 ◽  
pp. 516-519
Author(s):  
Hong Cai Yang ◽  
Ming Qing Wu
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Physical And Mechanical Properties ◽  
Machining Accuracy ◽  
Affecting Factors ◽  
Machined Surface ◽  
Process Measures ◽  
Factors Affecting ◽  
Mechanical Products ◽  
Quality Assurance Measure

The use of mechanical products to improve performance and increase the service life of components and composition of the product processing quality is closely related to machining quality is the basis of product quality assurance. Measure of good or bad quality parts machining the main indicators are: machining accuracy and surface roughness. This paper mainly affect parts of the surface roughness factor, parts of the surface layer of the physical and mechanical properties (surface work hardening, residual stress, microstructure change and grinding burn), surface quality performance parts and other factors affecting the analysis and research to improve the quality of machined surface process measures.

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