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.

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.

scholarly journals On-Line Inspection of the Surface Roughness of Workpiece in Ultraprecision Machining

2010 ◽  
Vol 126-128 ◽  
pp. 744-751 ◽  
Author(s):  
Hsi Hsun Tsai ◽  
Hui Ping Feng
Keyword(s):  
Surface Roughness ◽  
Light Scattering ◽  
Electroless Nickel ◽  
Green Laser ◽  
Ultraprecision Machining ◽  
Machined Surface ◽  
Tool Marks ◽  
On Line ◽  
Photodiode Array

An in situ technique to determine the surface roughness of ultraprecision machining using optical characteristic effects is fundamental as probes are not used, which prevents contact damage on the surface. Because the plastic lens molding reprints the roughness of the mold core fabricated by machining, tool marks result in the poor surface of the plastic lens. The machined surface can reflect the input light of a green laser with a short wavelength of 532 nm. By varying the feed rate of the ultraprecision machining, several samples of the electrolyte-less nickel with different surface roughness have been examined using the green laser and the photodiode array. The distribution of the optical scattering effect of each sample under the light source of green laser is derived for prediction of the surface roughness. The results show that greater surface roughness produces more expansive distribution of light scattering. In addition, the bidirectional scatter distribution function (BSDF) of the machined surface is found to be proportional to roughness. Using the ratio of the main and the side measuring channels of the photodiode array, a suitable approach to establish the relationship between light scattering and surface roughness can be developed. The laser and the photodiode array are found to efficiently predict the surface roughness of the ultraprecision machined electroless nickel.

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.

scholarly journals Ultra-High-Speed Magnetic Abrasive Surface Micro-Machining of AISI 304 Cylindrical Bar

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 489 ◽  
Author(s):  
Cheng Yin ◽  
Rui Wang ◽  
Jeong Kim ◽  
Sang Lee ◽  
Sang Mun
Keyword(s):  
Surface Roughness ◽  
Plastic Strain ◽  
High Speed ◽  
Precision Machining ◽  
Plastic Strains ◽  
Abrasive Machining ◽  
Machined Surface ◽  
Aisi 304 ◽  
Ultra High Speed ◽  
Ultra Precision

The ultra-high-speed magnetic abrasive machining (UHSMAM) process is a surface improvement technique, which has been widely used to minimize the surface accuracy and change the precision morphology of difficult-to-machine materials. Surface integrity plays an important role in the machining process, because it is used to evaluate the high stress and the loaded components on the machined surface. It is important to evaluate the plastically deformed layers in ultra-precision machining surface of material. However, the usual plastic strains in the ultra-precision machining surface are significantly difficult to consider. In this paper, an ultra-high-speed magnetic abrasive machining technique is used to improve the surface accuracy and dimensional accuracy of an AISI 304 bars. Additionally, the subsequent recrystallizations technique is used for measuring the plastic strain on machined surface of AISI 304 bars. The purpose of this paper is to evaluate the effects of an UHSMAM process on the plastic strains and the strain energy of the machined surface, and to evaluate the residual strain in the plastic deformation of AISI 304 bars materials by analyzing a plastically deformed layer. The results showed that the plastic strain of the material did not change after machined by an UHSMAM process. Based on the results, an UHSMAM process could significantly improve the surface roughness, micro-diameter, and removal weight of AISI 304 bars effectively. The surface roughness Ra of AISI 304 bars was improved from 0.32 µm to 0.03 µm for 40 s of machining time at 80,000 rpm of workpiece revolution speed.

Research on Surface Roughness Prediction Model Based on Genetic Algorithm for Optical Ultra-Precision Machining

2007 ◽  
Vol 10-12 ◽  
pp. 369-373
Author(s):  
Jian Jun Du ◽  
Chi Fai Cheung ◽  
Suet To ◽  
Z.Y. Liu
Keyword(s):  
Numerical Simulation ◽  
Genetic Algorithm ◽  
Surface Roughness ◽  
Linear Regression ◽  
Precision Machining ◽  
Mathematics Model ◽  
Simulation Test ◽  
New Model ◽  
Roughness Prediction ◽  
Ultra Precision

In this paper a dynamic non-linear mathematics model is proposed to predict the surface roughness in optical ultra-precision machining, which can be automatically built by evoling computer program of genetic algorithm. The new model can improve the fitting and predicting accuracy, compared with the traditional linear regression model. The numerical simulation test proves the effectiveness and accuracy of new model.

Micro-Quality Control on Ultra-Precision Machining of Sapphire Substrates

2010 ◽  
Vol 102-104 ◽  
pp. 738-741
Author(s):  
Hai Zhou ◽  
Li Gang Bai ◽  
Dai Pin Wang
Keyword(s):  
Surface Roughness ◽  
Ph Value ◽  
Diamond Wheel ◽  
Precision Machining ◽  
New Approach ◽  
Sapphire Substrates ◽  
Ductile Mode ◽  
Ultra Precision ◽  
Main Factors

This paper proposed a new approach to control the micro-quality of sapphire substrate, in order to grow GaN on substrate. The main factors that influence macro-quality are the method of slicing, grinding and polishing. Thread speed of slicing is less than 0.5m/s. Ductile mode grinding of substrate is achieved by #3000 diamond wheel and feed of 1μm/r. The suitable polishing conditions are that the SiO2 grain size is less than 10nm, the concentration SiO2 is 3％, pH value of polishing liquid is 10.5 and polishing stress is 190Pa. The undamaged substrates have been obtained steadily. The surface roughness RMS is less than 0.4 nm.

A novel anisotropic assessment method for nanometric surface roughness of ultra-precision diamond milling

2021 ◽  
pp. 095440622110028
Author(s):  
Pan Guo ◽  
Zhiwen Xiong ◽  
Shaojian Zhang
Keyword(s):  
Surface Roughness ◽  
Probability Distribution ◽  
Assessment Method ◽  
Precision Machining ◽  
Noise Effects ◽  
Ultra Precision ◽  
Effective Assessment ◽  
Diamond Milling

Ultra-precision diamond milling (UPDM) is one of ultra-precision machining approaches, providing nanometric surface roughness (NSR). The NSR exhibits rich anisotropic features, which is very sensitive to noise. However, there is lack of effective assessment of the anisotropic NSR. Therefore, the study proposed surface difference and surface curvatures as extra parameters to estimate the anisotropic NSR of UPDM. Moreover, noise effects were reduced by probability distribution with the 95–99 rule. Significantly, the proposed method effectively represents the anisotropic assessment of the NSR of UPDM.

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.

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