Optical Effects of Surface Finish by Ultraprecision Single Point Diamond Machining

Author(s):  
Lei Li ◽  
Stuart A. Collins ◽  
Allen Y. Yi

The single point diamond turning process has been used extensively for direct optical surface fabrication. However, the diamond machined surfaces have characteristic periodic tool marks, which contribute to reduced optical performance such as scattering and distortion. In this paper, studies of the characteristics of diamond machined surface and scattering from the diamond machined surfaces are presented. Four different parameters, the first order optical diffraction, the zero order reflection, the surface roughness, and the residual tool mark depth, are used as indicators for the machined surface quality. Four sets of tests are presented showing the relationship between machined surface quality and machining conditions such as spindle speed, feedrate, and machining process. Finally, an empirical model is given based on the measurements.

2007 ◽  
Vol 364-366 ◽  
pp. 544-549
Author(s):  
Ming Chu Kong ◽  
Wing Bun Lee ◽  
Chi Fai Cheung ◽  
Suet To

The formation of tool marks in single-point diamond turning is a fundamental study of the effect of materials swelling and recovery on surface roughness on a machined surface. A series of orthogonal face cutting tests has been conducted among plate aluminum alloy, oxygen-free high conductivity copper and electroless nickel phosphorus under the same cutting conditions by the use of facet tools with different front clearance angles. The results show that the regular width of the undulating pattern in tool marks could be explained by side swelling and the micro-waviness within a tool mark is caused by burnishing and recovery.


Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1110
Author(s):  
Menghua Zhou ◽  
Jianpeng Wang ◽  
Guoqing Zhang

In the field of single-point diamond turning (SPDT), machining ferrous metal is an important research topic with promising application. For SPDT of ferrous metal, the influence of lubricant on the workpiece surface morphology remains to be studied. In this study, three lubricant machining environments were selected to carry out specific control experiments. The machined surface morphology and cutting force in different lubricant machining environments were analyzed. The experiment results showed that the lubricant environment will have significant impacts on the quality of the machined surface morphology of ferrous metal. In the environment of minimum quantity lubrication machining (MQLM-oil), better machined surface quality can be obtained than that in ordinary dry machining (ODM) and high-pressure gas machining (HGM). Furthermore, the cutting force captured in the ODM and HGM environment increased with the increase of the cutting depth, while the cutting force in the MQLM-oil environment remained almost unchanged. That indicates MQLM-oil can suppress the formation of hard particles to improve the machining quality.


2018 ◽  
Vol 8 (8) ◽  
pp. 1353
Author(s):  
Tao Chen ◽  
Fei Gao ◽  
Suyan Li ◽  
Xianli Liu

Carbon fiber reinforced plastic (CFRP) is typically hard to process, because it is easy for it to generate processing damage such as burrs, tears, delamination, and so on in the machining process. Consequently, this restricts its wide spread application. This paper conducted a comparative experiment on the cutting performance of the two different-structure milling cutters, with a helical staggered edge and a rhombic edge, in milling carbon fiber composites; analyzed the wear morphologies of the two cutting tools; and thus acquired the effect of the tool structure on the machined surface quality and cutting force. The results indicated that in the whole cutting, the rhombic milling cutter with a segmented cutting edge showed better wear resistance and a more stable machined surface quality. It was not until a large area of coating shedding occurred, along with chip clogging, that the surface quality decreased significantly. At the stage of coating wear, the helical staggered milling cutter with an alternately arranged continuous cutting edge showed better machined surface quality, but when the coating fell off, its machined surface quality began to reveal damage such as groove, tear, and fiber pullout. Meanwhile, burrs occurred at the edge and the cutting force obviously increased. By contrast, for the rhombic milling cutter, both the surface roughness and cutting force increased relatively slowly.


Author(s):  
Tao Chen ◽  
Weijie Gao ◽  
Guangyue Wang ◽  
Xianli Liu

Torus cutters are increasingly used in machining high-hardness materials because of high processing efficiency. However, due to the large hardness variation in assembled hardened steel workpiece, the tool wear occurs easily in machining process. This severely affects the machined surface quality. Here, we conduct a research on the tool wear and the machined surface quality in milling assembled hardened steel mold with a torus cutter. The experimental results show the abrasive wear mechanism dominates the initial tool wear stage of the torus cutter. As the tool wear intensifies, the adhesive wear gradually occurs due to the effect of alternating stress and impact load. Thus, the mixing effect of the abrasive and adhesive wears further accelerates tool wear, resulting in occurrence of obvious crater wear band on the rake face and coating tearing area on the flank face. Finally, the cutter is damaged by the fatigue wear mechanism, reducing seriously the cutting performance. With increase of flank wear, moreover, there are increasingly obvious differences in both the surface morphology and the cutting force at the two sides of the joint seam of the assembled hardened steel parts, including larger height difference at the two sides of the joint seam and sudden change of cutting force, as a result, leading to decreasing cutting stability and deteriorating seriously machined surface quality.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5943
Author(s):  
Arminder Singh Walia ◽  
Vineet Srivastava ◽  
Mayank Garg ◽  
Nalin Somani ◽  
Nitin Kumar Gupta ◽  
...  

In electrical discharge machining (EDM), the machined surface quality can be affected by the excessive temperature generation during the machining process. To achieve a longer life of the finished part, the machined surface quality plays a key role in maintaining its overall integrity. Surface roughness is an important quality evaluation of a material’s surface that has considerable influence on mechanical performance of the material. Herein, a sintered cermet tooltip with 75% copper and 25% titanium carbide was used as tool electrode for processing H13 steel. The experiments have been performed to investigate the effects of EDM parameters on the machined surface roughness. The findings show that, as the pulse current, pulse length, and pulse interval are increased, the surface roughness tends to rise. The most significant determinant for surface roughness was found to be pulse current. A semi-empirical surface roughness model was created using the characteristics of the EDM technique. Buckingham’s theorem was used to develop a semi-empirical surface roughness prediction model. The semi-empirical model’s predictions were in good agreement with the experimental studies, and the built empirical model based on physical features of the cermet tooltip was tested using dimensional analysis.


2013 ◽  
Vol 748 ◽  
pp. 56-60 ◽  
Author(s):  
M. Sayuti ◽  
Ahmed A.D. Sarhan ◽  
S. Salem

In recent years, the energy efficiency improvement has become significant due to rapid consumption of world's energy resources. Particularly in manufacturing industry, hard turning process is one of the most fundamental metal removal processes that require huge power consumption and it could be improved in term of energy usage by many alternatives. At the same time, the improvement in term of machined surface quality is become a need since it would reflect appearance, performance and reliability of the products. As for example in the CNC machining field, one of the solution for this issue is by increasing the effectiveness of the existing lubrication systems as it could improve the machined surface quality, reduce the power required to overcome the friction component in batch production of machining process and reduce the oil consumption. The effectiveness of the lubrication system could be improved by introducing the nanobase lubrication system for much less power consumption as the rolling action of billions units of nanoparticle in the tool chip interface could reduce the cutting forces significantly. In this research work, the possibility of using SiO2 nanobase lubrication system is investigated to reduce the machining power consumption as well as improving surface quality in hard turning process of AISI4140.


2011 ◽  
Vol 314-316 ◽  
pp. 984-987
Author(s):  
Qing Liang Zhao ◽  
Jun Yun Chen ◽  
Jian Luo

The swelling effect is an important factor to affect surface generation in SPDT. Face cutting experiments are conducted for copper, aluminum alloy and electroless nickel phosphorus to analyze the swelling effect including the relationship between it and cutting parameters as well as effect of material property. How the material swelling affects surface roughness is also studied in this paper. The results indicate that the swelling effect is influenced by spindle speed and material property more remarkably when compared to feed rate and depth of cut. In addition, a softer and more ductile material will lead to a stronger material recovery, a lower swelling proportion, a lower tool mark height and a smoother machined surface. The result reveals that the swelling effect must be considered when predicting surface roughness in SPDT


2012 ◽  
Vol 500 ◽  
pp. 82-88 ◽  
Author(s):  
Cai Xu Yue ◽  
Xian Li Liu ◽  
Da Wei Sun ◽  
Ming Yang Wu

For its good processing flexible, economic and environmental protection performance, hardened steel GCr15 is used widely in car and energy industry. Although surface quality in machining process is not controlled well, that restricts application of hardened steel GCr15 extensive to a certain degree. Therefore, this study revealed the effect of cutting parameters on surface roughness. Also influence of cutting conditions on surface morphology and organization generation mechanism of subsurface were stuied for high-speed cutting hardened steel GCr15. Appear reasons of plastic side flow on surface was researched. Also, effect of tool wear on surface quality was studied as well. The research results provided theoretical basis for rational choice for high speed hardened steel cutting process.


Author(s):  
Pavel Polák ◽  
Petr Dostál ◽  
Katarína Kollárová

This article describes the evaluation of machined material roughness in speed turning on a machining centre Doosan Puma 700 LY. The machined surface of semi-finished products from steel 14 260 was compared at selected cutting conditions. A half of compared samples from steel 14 260 was in the original, thermally untreated condition (mild steel), and the second half of samples was thermally treated (hardened steel, with a hardness of samples 50 HRC). The experiment focused on turning the selected samples in order to evaluate the roughness of machined surfaces. Cutting tool shift was variable during individual measurements. This experiment contributes to a quick orientation in the given issue and points out to optimisation of cutting conditions.


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