Form Accuracy of Optical Mould Inserts Made from Rapidly Solidified Aluminium Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 62-68
Author(s):  
Khaled Abou-El-Hossein
Keyword(s):  
High Precision ◽  
Surface Finish ◽  
Single Point ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Parameters ◽  
Optical Surface ◽  
Form Accuracy ◽  
Optical Surfaces ◽  
Rapidly Solidified

Plastic optical components and lenses produced in mass quantities are usually manufactured using high-precision plastic injection technology. For that, high-precision plastic moulds with aluminium optical inserts made with extremely high dimension accuracy and high optical surface quality are used. Ultra-high precision single-point diamond turning have been successfully used in shaping optical mould inserts from various aluminium grades such as traditional 6061. However, extreme care should be taking when selecting machining parameters in order to produce optically valid surfaces before premature tool wear takes place especially when the machined optical materials has inadequate machining database. The current experimental study looks at the effect of cutting conditions on optical surfaces made from aluminium. The study embarks on helping establish some diamond machining database that helps engineers select the most favourable cutting parameters. The papers reports on the accuracy and surface finish quality received on an optical surface made on mould inserts from a newly developed aluminium alloy. Rapidly solidified aluminium (RSA) grades have been developed recently to address the various problems encountered when being cut by single-point diamond turning operation. The material is characterised by its extremely fine grained microstructure which helps extend the tool life and produce optical surfaces with nanometric surface finish. It is found the RSA grades can be successfully used to replace traditional optical aluminium grades when making optical surfaces. Surface finishes of as low as 10 nanometres and form accuracy of less than one micron can be achieved on RSA.

The Cutting Parameter Affecting to Surface Roughness in Single-Point Diamond Turning

2014 ◽  
Vol 887-888 ◽  
pp. 1236-1239
Author(s):  
Wang Hao ◽  
Yu Zhang ◽  
Qi Ming Xie
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Surface Finish ◽  
Diamond Tool ◽  
Single Point ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Process ◽  
Form Accuracy ◽  
Edge Sharpness

Single-point diamond turning (SPDT) is a machining process making use of a monocrystal diamond tool which possesses nanometric edge sharpness, form reproducibility and wear resistance. The process is capable of producing components with micrometre to submicrometre form accuracy and surface roughness in the nanometre range. The cutting parameters that can make an effect on surface finish and form accuracy of SPDT such as spindle speedfeed ratedepth of cut and so on.

Effects of Cutting Fluids on Surface Roughness in Single-Point Diamond Turning of Rapidly Solidified Aluminium (RSA 431)

2020 ◽  
Vol 853 ◽  
pp. 18-23
Author(s):  
F.A Oyekunle ◽  
Khaled Abou-El-Hossein
Keyword(s):  
Surface Roughness ◽  
Metal Removal ◽  
Single Point ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Cutting Fluid ◽  
Depth Of Cut ◽  
Cutting Fluids ◽  
Machining Processes ◽  
Rapidly Solidified

Single-point diamond turning is a technique of ultra-high precision machining that provides excellent quality of surface for mirrors, spherical and aspherical components. In SPDT just like other machining processes, cutting fluid plays an important role in metal removal and tool condition which largely influence the surface of diamond turned surface. In this paper, the surface roughness of diamond turned RSA 431 was studied by investigating the effect of kerosene mist and water as cutting fluids. Higher order response surface of Box-Behnken design was generated using fewer runs than a normal factorial technique. The cutting parameters that were varied for both experiments were depth of cut, feed and, speed. Taylor Hobson PGI Dimension XL surface Profilometer was used to measure the surface roughness after each experimental run. The results show that water when used as cutting fluid during machining, produces better surface roughness than kerosene mist. Predictive models for surface roughness were developed for each experiment. Values from the Mean Absolute Percent Error (MAPE) was used to evaluate and compare the two models to determine the accuracy. RSM also proved to be a better methodology of predicting surface roughness.

Effect of machining parameters and vibration on polymethylmethacrylate curved surface in single-point diamond turning

2020 ◽  
pp. 251659842094172
Author(s):  
Kuldeep A. Mahajan ◽  
Raju Pawade
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Feed Rate ◽  
Single Point ◽  
Optical Devices ◽  
Diamond Turning ◽  
Curved Surface ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Workpiece Material

Single-point diamond turning (SPDT) is an emerging process for achieving nanometric surface finish, required in various optical devices made from metals like aluminum, copper, and nonmetals like polymers. The optical devices are manufactured in different shapes and profiles, preferably flat and curved surfaces. During the manufacturing of optical devices, controllable and noncontrollable parameters affect the desired surface finish. In this article, controllable machining parameters such as the incremental distance of X slide, feed rate, spindle speed, and depth of cut are selected to study their effect on surface finish and vibration generation of the curved surface. The chosen workpiece material is polymethylmethacrylate (PMMA). Design of experiment (DoE) is used to find out the optimum parameters of surface finish and infeed vibration responses. According to the Taguchi and analysis of Variance (ANOVA) analysis, the feed rate is the most influencing parameter for surface roughness, and incremental distance is for infeed vibration. A confirmation test is carried out to verify the experimental responses with a mathematical regression model, and it shows a close difference within 2.7 percent. Further, minimum surface roughness is perceived as 12.4 nm, corresponding to an infeed vibration amplitude of 4.9 µm/s2, which is signified at a lower frequency.

Diamond Insert Wear when Turning Rapidly Solidified Aluminium RSA 443 of High-Silicon Content

2015 ◽  
Vol 828-829 ◽  
pp. 265-271 ◽  
Author(s):  
Zwelinzima Mkoko ◽  
Khaled Abou-El-Hossein
Keyword(s):  
Tool Wear ◽  
Diamond Tool ◽  
Natural Diamond ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Edge Wear ◽  
Rapidly Solidified

Rapid solidification of molten metals has been recently used to generate a new group of alloys having ultra-fine microstructures and high end mechanical properties. Therefore, such alloys can be successfully used in the optics industry to produce diamond machined mirrors and mould inserts for plastic lens injection. Rapidly solidified aluminium grades characterised by their ultra-fine grains can be used to replace traditional optical aluminium such as 6061-T6 which has coarse microstructure when making optics. However, there is currently no data available on the performance of these new grades in terms of diamond tool wear when machined in single-point diamond turning operation. This paper reports on the wear mechanisms of natural diamond tools when turning RSA 443 which is a new aluminium grade produced by rapid cooling process. Although this new aluminium grade enjoys fine microstructure, it is harder than traditional optical aluminium because of its increased content of silicon (about 40%). Therefore, there is a need to establish a deeper understanding of diamond tool performance when using diamond turning of optical components from this material. In this study, three machining parameters, namely cutting speed, feed rate, and depth of cut, were varied at three levels and the edge wear of the diamond inserts was observed using scanning electron microscopy after 4 km of cutting distance. The first observations from this preliminary study show that tool wear of diamond is more sensitive to the change in cutting speed than it is for other cutting parameters. Wear is relatively high (12 µm) at the lowest cutting speed (500 rpm). However, at high cutting speed (3000 rpm) the edge wear was small (3 µm). This could be attributed to the increased impacts of cut the material on the cutting edge. The study also reports on the surface finish obtained at the different combinations of cutting parameters.

scholarly journals Effect of Nose Radius on Surface Roughness of Diamond Turned Germanium Lenses

2021 ◽  
Author(s):  
Adeniyi Adeleke ◽  
Abou-El-Hossein Khaled ◽  
Odedeyi Peter
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Single Point ◽  
Absolute Error ◽  
Diamond Turning ◽  
Machining Process ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Nose Radius

Abstract The desire for quality infrared lens with better surface finish has brought about the usage of brittle materials like germanium to be machined via a single point diamond turning machining process. However, achieving the required surface finish is complex if special machining techniques and approaches are not employed. In this paper, the effect of two different tool nose radius parameters on surface roughness of single point diamond turned germanium workpiece were studied and analyzed. The machining parameters selected for this experiment were feed, speed and depth of cut. Box-Behnken design was adopted to optimally create a combination of cutting parameters. Measurement of surface roughness after each run in both experiments was achieved using a Taylor Hobson PGI Dimension XL surface Profilometer. The resulting outcomes show that at most experimental runs, the surface roughness value decreased with an increase in nose radius. Mean absolute error was also used to compare the accuracy validation of the two models.

Research of Surface Generation Mechanisms in Single-Point Diamond Turning

2007 ◽  
Vol 364-366 ◽  
pp. 1296-1301
Author(s):  
Chi Fai Cheung ◽  
Wing Bun Lee ◽  
Suet To ◽  
Ling Bao Kong
Keyword(s):  
Surface Roughness ◽  
High Precision ◽  
Single Point ◽  
Diamond Turning ◽  
Surface Generation ◽  
Optical Surfaces ◽  
Surface Finishes ◽  
Generation Mechanisms

One of the remarkable achievements of nanotechnology is the ability to achieve nanometric surface finishes in single-point diamond turning of high-precision components for complex optical surfaces. A better understanding of the surface generation mechanisms is of prime importance for the development for the prediction of the surface roughness. This paper presents a study of mechanisms of nano-surface generation in single-point diamond turning of various types of materials.

Modelling of Electrostatic Charge in Ultra-High Precision Diamond Turning of Contact Lens Polymer

2019 ◽  
Vol 298 ◽  
pp. 135-140
Author(s):  
Muhammad Mukhtar Liman ◽  
Khaled Abou El Hossein
Keyword(s):  
High Precision ◽  
Contact Lens ◽  
Feed Rate ◽  
Contact Lenses ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Electrostatic Charge ◽  
Diamond Turning ◽  
Depth Of Cut ◽  
Electrostatic Charges

The electrostatic charges encountered by a cutting tool when turning advanced contact lenses are important as they reflect the quality and condition of the tool, machine, fixture, and sometimes even the surface finished which is responsible for tool wear and poor surface quality. This study investigates the influence of cutting parameters namely cutting speed, feed rate and depth of cut on electrostatic charge (ESC) which play the leading role in determining the machine economics and quality of machining contact lens polymers. An electrostatic charge model based on response surface statistical method is developed for reliably predicting the values of static charging based on its relationship to cutting parameters in ultra-high precision diamond turning of contact lenses. It is clearly seen that all the model terms are significant with cutting speed having the highest degree of significance followed by feed rate and the interaction of speed and feed. However, depth of cut has the lowest degree of significance on the electrostatics charge.

Effects of Machining Parameters on Surface Roughness when Ultra-High Precision Diamond Turning RSA443 Optical Aluminum

2019 ◽  
Vol 287 ◽  
pp. 30-34
Author(s):  
Zwelinzima Mkoko ◽  
Khaled Abou-El-Hossein
Keyword(s):  
Surface Roughness ◽  
Silicon Content ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Parameters ◽  
Turning Process ◽  
Optical Components ◽  
Box Behnken Design ◽  
Factors Influencing

In the globally competitive environment, surface roughness and finer tolerances are becoming stringent and certainly most critical for optical components. The aim of this study is to determine the effects of diamond turning process parameters on surface finish when diamond turning RSA 443 alloy having high silicon content. This alloy is a new grade of aluminum that has a potential to be used for production of various optical components. The experiments were conducted based on the Box-Behnken design with three diamond-turning parameters varied at three levels. A mathematical regression model was developed for predicting surface roughness. Further, the analysis of variance was used to analyze the influence of cutting parameters and their interaction in machining. The developed prediction model reveals that cutting speed and feed rate are the most dominant diamond turning factors influencing surface roughness.

Experiment and Discussion on Ultrasonic Vibration-Assisted Single Point Diamond Turning of Die Steels

2012 ◽  
Vol 497 ◽  
pp. 1-5
Author(s):  
Xiao Dan Xie ◽  
Yong Li ◽  
Cam Vinh Duong ◽  
Ahmed Al-Zahrani
Keyword(s):  
Tool Wear ◽  
Ultrasonic Vibration ◽  
Single Point ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Process ◽  
Die Steels ◽  
Ultra Precision ◽  
Promising Solution ◽  
Vibration Parameters

Traditionally, single point diamond turning (SPDT) can not process ferreous metals because of acute tool wear. Ultrasonic vibration-assisted cutting(UVC) provides a promising solution for the problem. In this paper, for the aim of directly obtaining mirror surface on die steels, UVC method was used combining with SPDT process. Experiments were carried out on an ultra precision turning machine, cutting parameters and vibration parameters were well-chosen, and two kind of feed rates, two kinds of prevailing die steels were experimented. Mirror surfaces were successfully achieved on face turning, with the best roughness of Ra16.6nm. And the surface roughness, surface texture and tool wear in machining process were discussed.

Sign in / Sign up

Export Citation Format

Share Document