Single Point Diamond Turning Research Articles

Study of stress-assisted nano-cutting mechanism of gallium arsenide

The high-performance manufacturing of hard-brittle materials by single-point diamond turning (SPDT) is a very active and challenging research area. The stress-assisted nano-cutting is a promising method for improving the machinability of hard-brittle materials. However, the simulation results in the existing stress-assisted nano-cutting model would contradict the actual condition due to the pre-stress being released before tool entry into the workpiece. A modified stress-assisted nano-cutting model with a virtual boundary between the workpiece and tool is proposed for the first time in this paper to investigate the nano-cutting process of GaAs material under different external stresses. The emergence of an atomic flow vortex during stress-assisted nano-cutting significantly enhances the quality of the machined surface, leading to a substantial reduction in both machined surface roughness (34.4 %) and subsurface damage (56.2 %), compared to the normal nano-cutting. By evaluating surface roughness, subsurface damage depth, morphological accuracy, cutting force, and removal efficiency, a pre-strain of 0.06 is determined to be the optimal pre-strain for stress-assisted nano-cutting. Moreover, the selection of optimal pre-strain remains unaffected by variations in the nano-cutting depth. TEM results demonstrate that the nano-cutting mechanism elucidated by the MD analysis accurately reflects the genuine deformation of the GaAs material.

Simplifying tailored generation of complex structured femtosecond pulses with easily fabricated phase plates

This article presents a novel approach to targeted 4f pulse shaping using phase plates fabricated by single-point diamond turning (SPDT) machining. The manufacturing of the phase plates using SPDT is versatile, cost-effective, fast, robust, and applicable across a wide range of optical materials, spanning from visible to far-infrared spectra (e.g., PMMA, ZnSe). Manufactured profiles can be used for phase manipulation and pulse structuring, analogously to programable spatial light modulators (SLM). We demonstrate that the pulse waveforms can be reproduced with high fidelity by simple simulations based on calculating optical path differences induced by the phase plate for each wavelength and taking into account the finite focal spot. The simulated and reconstructed frequency-resolved optical gating spectrograms featured G errors between 1–2% and intensity errors between 0.02–0.06. Even for complex structured pulses with the rms value of the time-bandwidth product reaching 12, our method maintains high precision, in some cases even reaching lower G error compared to simpler waveforms. Finally, we also show that the phase plate can be used to attain a set of uncorrelated pulse waveforms by moving the plate relatively to the dispersed laser spectrum. Overall, this approach bypasses common limitations associated with pulse shaping using SLMs, such as pixelation, pixel cross-talk, and spectral or laser fluences constraints.

Surface and subsurface response to the in-situ laser assistance in ultra-precision diamond turning of SiCp/Al composites

This study focuses on the application of in-situ laser-assisted single-point diamond turning (ILAT) on SiCp/Al metal matrix composites (MMCs), renowned for their exceptional mechanical properties and difficult-to-cut nature. The surface and subsurface response to the in-situ laser assistance under a small uncut chip thickness (UCT) is investigated. The results demonstrate that appropriate laser energy can reduce subsurface crystal defects while maintaining surface quality during machining. As the laser power increases, the surface damage pattern shifts from cut-through to fracture, eventually leading to severe matrix deformation. Slight compressive stress is observed on the Al phase of surfaces machined with either conventional single-point diamond turning (SPDT) or ILAT. Al crystals near the machined surface and SiC particles in the SPDT sample exhibit a notable accumulation of dislocations. Laser assistance is beneficial for mitigating dislocations and improving the crystalline integrity of Al grains, while Al grains close to the machined surface in both SPDT and ILAT samples present comparable amounts of stacking faults. The findings enhance the understanding of surface and subsurface generation of SiCp/Al composites in ILAT, providing a reference for the application of ILAT on other MMCs.

High precision polishing of aluminum alloy mirrors through a combination of magnetorheological finishing and chemical mechanical polishing

After the aluminum alloy mirror machined by single point diamond turning (SPDT), the residual tool marks and surface accuracy of the aluminum alloy mirror cannot meet the requirements of visible or ultraviolet light system. In this study, a processing method combining magnetorheological finishing (MRF) and chemical mechanical polishing (CMP) is proposed to realize the polishing of aluminum alloy mirrors with high efficiency, high precision and high-quality. Firstly, the properties and composition of passivation layer after MRF were analyzed and the polishing performance of acidic, neutral and alkaline alumina polishing fluid on passivation layer were investigated based on the computer numerical control (CNC) polishing equipment. Based on the experimental results, a new acidic nano-silica polishing fluid which is suitable for the efficient and high-quality removal of passivation layers on aluminum alloy surfaces was developed. Finally, a combined approach of MRF-CMP was used to the directly polishing of a rapidly solidified aluminum mirror (RSA-6061) with a diameter of 100 mm after SPDT. With two iterative of MRF-CMP polishing in 220 minutes, the surface accuracy of the aluminum alloy mirror was improved from 0.1λ (λ=632.8 nm) to 0.024λ, and the surface roughness (Ra) decreased from 3.6 nm to 1.38 nm. The experiment results manifest that high precision, and high-quality aluminum alloy mirror can be achieved by MRF-CMP method with the new developed acid nano-silica polishing fluid and suitable MR polishing fluid. The research results will provide a new strategy for ultra-precision direct polishing of aluminum alloy mirrors and will also give the important technical support for the extensive use of aluminum alloy mirror in visible light and ultraviolet optical systems.

Advancement of Analytical Model for Hydrophobic Rectangular Pillared Array on Al-Surface and Its Experimental Validation

AbstractOver the past few decades, self-cleaning surfaces have been significantly investigated due to their commercial applications in various fields. However, the researchers are still lagging in developing better mathematical models and fabricating hydrophobic surfaces for direct espousal in industry. In this study, a force-balanced system-based mathematical model is modified for a rectangular pillared array-based micro-structure and MATLAB simulations were used to validate it theoretically. The same pattern was developed on Al-surface using a single-point diamond turning (SPDT) machine experimentally. The experimental results were validated using coherence correlation interferometry (CCI), optical microscopy, drop shape analyser (DSA), and field emission scanning electron microscopy (FESEM). The experimentally estimated and theoretically predicted contact angles of the rectangular pillared array are found in close agreement. Further, the advancement in mathematical models and models-based surface manufacturing strategies can boost the research in this domain to develop robust self-cleaning hydrophobic surfaces.

ADVANCES IN ULTRAPRECISION DIAMOND TURNING: TECHNIQUES, APPLICATIONS, AND FUTURE TRENDS

Advances in ultraprecision diamond turning have revolutionized manufacturing processes across various industries, offering unparalleled precision and surface quality in the fabrication of optical components, microfluidic devices, and advanced mechanical parts. This review delves into the techniques, applications, and future trends in ultraprecision diamond turning, highlighting recent advancements and potential trajectories. Techniques in ultraprecision diamond turning have evolved significantly, driven by innovations in machine design, tooling materials, and control systems. Diamond turning machines equipped with ultra-stiff structures, high-speed spindles, and advanced feedback mechanisms enable sub-nanometer level accuracy and surface finishes down to Angstrom levels. Additionally, advancements in single-point diamond turning (SPDT), fast tool servo (FTS), and deterministic microgrinding (DMG) techniques further enhance the versatility and precision of the process. Applications of ultraprecision diamond turning span a wide range of industries, including aerospace, automotive, biomedical, and telecommunications. In optics manufacturing, diamond turning facilitates the production of aspheric lenses, freeform optics, and diffractive optical elements with unprecedented accuracy, contributing to the development of high-performance imaging systems and laser applications. Moreover, in the biomedical field, diamond-turned microfluidic devices enable precise control over fluid flow and particle manipulation, empowering advancements in drug delivery systems and lab-on-a-chip technologies. Future trends in ultraprecision diamond turning are poised to address challenges related to scalability, multi-material processing, and in-situ metrology. Integration of adaptive control algorithms and machine learning techniques promises enhanced process stability and predictive maintenance, optimizing productivity and reducing downtime. Furthermore, the development of hybrid manufacturing approaches, combining diamond turning with additive manufacturing or laser processing, offers novel avenues for fabricating complex, multi-functional components with improved efficiency and cost-effectiveness. The ongoing advancements in ultraprecision diamond turning techniques, coupled with diverse applications across industries, underscore its pivotal role in advancing manufacturing capabilities. Anticipated future trends hold promise for further expanding the scope and impact of this technology, driving innovation and pushing the boundaries of precision engineering.
 Keywords: Ultraprecision, Diamond, Turning, Technique, Review.

Sol–gel derived highly hydrophobic Polystyrene/SiO2 spray coatings on polished stainless steel and textured aluminium substrates

ABSTRACT In this study, sol–gel derived spray coatings of highly hydrophobic nature consisting of polystyrene (PS) and SiO2 nanoparticles were developed on polished stainless steel 321 (SS) and textured 6061 aluminium (Al) alloy substrates. The micro-structures on the Al surface were created through ultraprecision machining, known as single-point diamond turning (SPDT) machining. The polished SS and micro-structured Al were coated with PS/SiO2 using a spray coating technique by maintaining a pressure of 4–5 kPa, and positioning the nozzle 20–30 cm away from the substrates. The textured surface of Al was characterised using coherent correlational interferometry (CCI). The PS modified SiO2 nanoparticles and their coatings were characterised using Fourier-Transform Infrared Spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM). The resulting coating exhibited a micro-nano hierarchical roughness due to the presence of SiO2 nanoparticles and their fine size clusters. The polished SS surface showed static water contact angles of 93.3° and 143.5° before and after coating, respectively. Similarly, the polished and coated structured Al surface exhibited water contact angles of 85.6° and 144.3° before and after coatings. Such coatings can exhibit a great potential particularly in the field of self-cleaning technologies.

Machinability and Surface Properties of Cryogenic Poly(methyl methacrylate) Machined via Single-Point Diamond Turning.

Poly(methyl methacrylate) (PMMA), with a glass transition temperature (Tg) over 100 °C, shows good mechanical and optical properties and has broad applications after being machined with single-point diamond turning (SPDT) at room temperature. Because of the high Tg, current efforts mostly focus on optimizing machining parameters to improve workpiece precision without considering the modification of material properties. Cryogenic cooling has been proven to be an effective method in assisting ultra-precision machining for certain types of metals, alloys, and polymers, but has never been used for PMMA before. In this work, cryogenic cooling was attempted during the SPDT of PMMA workpieces to improve surface quality. The machinability and surface properties of cryogenically cooled PMMA were investigated based on the mechanical properties at corresponding temperatures. Nanoindentation tests show that, when temperature is changed from 25 °C to 0 °C, the hardness and Young's modulus are increased by 37% and 22%, respectively. At these two temperature points, optimal parameters including spindle speed, feed rate and cut depth were obtained using Taguchi methods to obtain workpieces with high surface quality. The surface quality was evaluated based on the total height of the profile (Pt) and the arithmetic mean deviation (Ra). The measurement results show that the values of Pt and Ra of the workpiece machined at 0 °C are 124 nm and 6 nm, respectively, while the corresponding values of that machined at 25 °C are 291 nm and 11 nm. The test data show that cryogenic machining is useful for improving the form accuracy and reducing the surface roughness of PMMA. Moreover, the relationship between temperature, material properties and machinability weas established with dynamic mechanical analysis (DMA) data and a theoretical model. This can explain the origin of the better surface quality of the cryogenic material. The basis of this is that temperature affects the viscoelasticity of the polymer and the corresponding mechanical properties due to relaxation. Then, the material property changes will affect surface profile formation during machining. The experimental results and theoretical analysis show that cryogenically cooled PMMA has good machinability and improved surface quality when using SPDT compared to that at ambient temperature.

Topology Optimization of a Single-Point Diamond-Turning Fixture for a Deployable Primary Mirror Telescope

CubeSats, known for their compact size and cost effectiveness, have gained significant popularity. However, their limited size imposes restrictions on the optical aperture and, consequently, the Ground Resolution Distance in Earth Observation missions. To overcome this limitation, the concept of deployable optical payloads with segmented primary mirrors which can unfold like petals has emerged, enabling larger synthetic apertures and enhanced spatial resolution. This study explores the potential benefits of leveraging Additive Manufacturing (AM) and Topology Optimization (TO) in the realm of ultra-precision machining, specifically single-point diamond machining. The goal is to reduce fixture weight while improving stiffness to minimize deformations caused by rotational and cutting forces which compromise optical performance. Through Finite Element Analysis, this research compares conventionally machined fixtures with those produced using AM and TO techniques. The results reveal that concept designs created via TO can achieve a remarkable 68% reduction in weight. This reduction makes the assembly, including the machining fixture and 12 U deployable segments, manageable by a single operator without the need for specialized lifting equipment. Moreover, these innovative designs lead to substantial reductions of up to 86% and 51% in deformation induced by rotational and cutting forces, respectively.

Enhancement of optical surface quality based on real-time compensation of temperature-driven thermal errors in diamond turning

In diamond turning, thermal error compensation is critical for improving machining accuracy. In the ultra-precision diamond turning of optical devices, fluctuations in room temperature cause periodic waviness on the machined surface, which degrades the optical performance. Surface finishing processes, such as polishing, are generally required to remove surface waviness. However, the materials used in the polishing process can pollute the environment. Moreover, the polishing process produces a large amount of waste, including contaminated alcohol and tissue. This study presents a new method for compensating temperature-driven thermal errors during single-point diamond turning (SPDT) using machine learning. Long short-term memory (LSTM), an artificial recurrent neural network architecture, was used to estimate the thermal error from the temperatures observed at several locations around the SPDT machine. The performance of the proposed method was evaluated by comparing its estimation accuracy with those of other machine learning methods (multiple linear regression and support vector machine). The thermal error was compensated for by controlling the tool position according to the estimated thermal error. To evaluate the results of the thermal error compensation, the intensities of the laser beam profiles reflected from two flat aluminum mirrors with diameters of 100 mm were observed at several propagation distances. The waviness formed on the uncompensated surface resulted in a dramatic increase in intensity owing to the constructive interference caused by Bragg scattering, whereas the intensity of the reflection from the compensated surface did not vary as the waviness was removed.

Online chatter detection for single-point diamond turning based on multidimensional cutting force fusion

Single-point diamond turning (SPDT) is an advanced ultra-precision processing technology that is widely used in machining optical surfaces and microstructures. However, due to insufficient stiffness or damping of the cutting system and the high strength of the workpiece material, chatter inevitably occurs in the machining process, resulting in inferior workpieces and short tool lives. Thus, chatter detection at the early stage is vital to avoid its adverse effects, and a multidimensional cutting force fusion-based online chatter detection method for SPDT is proposed in this work. According to the characteristics of each component of the cutting force in the chatter SPDT process, the stable frequency component is filtered out, and then an artificial constant offset is added. On this basis, the cutting force-based multidimensional information fusion signal and its derivative are set as the detection variables. The chatter detection indicator is developed based on the sum of squares of the detection variable’s frequency spectrum amplitude, with the chatter warning threshold being adaptively determined by the upper limit of the 95% confidence interval of the same indicator obtained from the measurement noises under air cuts. Experiments conducted under various cutting conditions prove that the proposed method can accurately and timely detect weak chatter, thereby preventing further severe chatter and its detrimental effects on the SPDT system.

Design and Analysis of Ultra-Precision Smart Cutting Tool for In-Process Force Measurement and Tool Nanopositioning in Ultra-High-Precision Single-Point Diamond Turning.

Ultra-high-precision single-point diamond turning (SPDT) is the state-of-the-art machining technology for the advanced manufacturing of critical components with an optical surface finish and surface roughness down to one nanometer. One of the critical factors that directly affects the quality of the diamond-cutting process is the cutting force. Increasing the cutting force can induce tool wear, increase the cutting temperature, and amplify the positioning errors of the diamond tool caused by the applied cutting force. It is important to measure the cutting force during the SPDT process to monitor the tool wear and surface defects in real time. By measuring the cutting force in different cutting conditions, the optimum cutting parameters can be determined and the best surface accuracies with minimum surface roughness can be achieved. In this study a smart cutting tool for in-process force measurement and nanopositioning of the cutting tool for compensating the displacements of the diamond tool during the cutting process is designed and analyzed. The proposed smart cutting tool can measure applied forces to the diamond tool and correct the nanometric positioning displacements of the diamond tool in three dimensions. The proposed cutting tool is wireless and can be used in hybrid and intelligent SPDT platforms to achieve the best results in terms of optical surface finish. The simulation results are shown to be almost consistent with the results of the derived analytical model. The preliminary results pave the way for promising applications of the proposed smart cutting tool in SPDT applications in the future.

Reducing the cutting tool wear in diamond turning of Zerodur glass-ceramic by the mechanical cleaning effect of ultrasonic vibration assistance

The effects and mechanisms of using ultrasonic vibration assistance (U.V.-assisted machining) combined with straight-nosed cutting tools on reducing the cutting tool wear in single-point diamond turning (SPDT) of Zerodur glass-ceramic are analysed and experimentally investigated. Aiming at the predominant abrasive wear in machining hard and brittle materials, analyses have shown that applying appropriate ultrasonic vibration to the cutting tool can induce considerable inertial acceleration to the wear particles residing on the tool-work interface for promoting their ejection from the contact area to reduce the abrasion. Meanwhile, the high thermal conductivity of diamond can prevent the possible excessive temperature elevation of the cutting tool surface that may result from the in-plane vibration components. To verify these, a longitudinal ultrasonic vibrator that works together with the Poisson's effect was designed for the SPDT processes with straight-nosed cutting tools. Machining tests on Zerodur optics have shown that the assistant ultrasonic vibration is able to decrease the tool flank wearland width by about 30 %, and the groove-like scratches on the tool flank wearland surface were reduced, which is consistent with the analytical deductions. Besides, no significant traces of structural change, element diffusion, and oxidation were found on the worn cutting tool surfaces under either the assisted or unassisted cutting conditions. The experiments have also shown that the enhanced durability of cutting tools has extended the cutting tool life for maintaining good machined surface quality, which is particularly beneficial to the ultra-precision machining of large-size optical parts.

Investigation on the ultra-precision diamond turning of ZnSe aspheric surfaces using straight-nosed cutting tools

Theoretical and experimental investigations on the machining performance and mechanisms in single-point diamond turning (SPDT) of ZnSe aspheric surfaces using straight-nosed cutting tools have been carried out. Analyses of the chip formation process have shown that using straight-nosed cutting tools can significantly reduce the cut thickness by about 60 % compared with using round-nosed cutting tools for facilitating the ductile-mode material removal and reducing surface damages. The analyses have also shown that the height of residual feed marks can be reduced by using the straight-nosed cutting tools by about 80 %, which can further improve the machined surface integrity. Experiments on the machining performance of using straight-nosed and round-nosed cutting tools were conducted to verify the analytical deductions. It has been shown that nano-scale surface finish with surface roughness Ra ∼ 1.5 nm can be achieved by using straight-nosed cutting tools, which is significantly improved comparing with that by the round-nosed cutting tools (Ra ∼ 7.8 nm) and is consistent with the analytical results. Needle-like chip with periodical layered structure was collected from the SPDT processes using straight-nosed cutting tools, indicating a relatively continuous chip formation process under the ductile-mode material removal. Raman spectroscopy has shown increased metallization of ZnSe occurred during the machining with straight-nosed cutting tools, which is considered to reduce the brittle fractures along with the chip formation process. It has been further found that the straight-nosed cutting tool can reduce work adhesion and micro-edge chipping of cutting tools for extending the cutting tool life.

A single point diamond turning and integrated sensory system in nano machining: A survey, research issues and challenges

The modernization in the Nano machining field is increasing rapidly because of the monetary benefits and applications of Nano size product features. Scientists have made fewer attempts to do research in the field of Nano-turning, such as material removal at the Nano-scale. The principles of Nano-scale turning were discussed, as well as contemporary breakthroughs in sensory systems. Surface finishing of Nano-turned components is required due to material anisotropy, tool geometry, and machining settings, as surface finishing is a critical performance aspect.This article discusses Nano-turning advancements, with a focus on Single Point Diamond Turning (SPDT). This article focuses on Integrated Sensory Systems for SPDT as well as nanoscale computer modelling of cutting mechanics. Future research areas in Nano scale turning and machining include active control and in-process adjustments of sensors and automated systems for Nano-turning.

INVESTIGATION OF 3D SURFACE TOPOGRAPHY FEATURES ON THE POLYCRYSTALLINE DIAMOND TURNING OF ALUMINA

The product’s surface quality and service performance depend on the surface integrity features formed by the machining process. Surface integrity consists of many features including surface topography and others. In this work, 3D (areal) surface topography features, particularly height variations, were investigated on the polycrystalline diamond (PCD) turning of alumina. Variations of the areal unevenness and height distribution parameters, namely arithmetic mean deviation (Sa), maximum peak height (Sz), skewness (Ssk) and kurtosis (Sku), with respect to turning parameters such as spindle speed (1000, 2000 n 3000 rpm), feed rate (0.05, 0.075 & 0.1 mm/rev) and depth of cut (1, 3 & 5 [Formula: see text]m) were studied. The Taguchi technique was carried out in this study based on the L9 standard orthogonal array for optimizing the turning parameters for the generation of better topography features. The error analysis was done with the experimental results and the error variations were noticed to be less than 10%. Based on the experimental results, the best surface figure combination of Sa 0.67 [Formula: see text]m, Sz 3.18 [Formula: see text]m, Ssk 0.0039 and Sku 3.06 was found at the employment of spindle speed of 1500 rpm, feed rate of 0.1 mm/rev, and depth of cut of 1 [Formula: see text]m. The distribution of peaks and valleys formed over the PCD-turned alumina surfaces may influence the different functional properties such as fatigue, friction, wear, etc. Besides, the results were examined through means of responses and analysis of variance (ANOVA). The test results also reported that the depth of cut outperforms other hard turning parameters over the surface topography features of the turned alumina ceramics. At a lower depth of cut, the cutting tool is involved in the shearing action which causes the stable material removal of alumina ceramics through an appreciable chip formation.

Analysis and Prediction of Image Quality Degradation Caused by Diffraction of Infrared Optical System Turning Marks

This paper addresses the issue of reduced image quality due to annular turning marks formed by single-point diamond turning (SPDT) during the processing of metal-based mirrors and infrared lenses. An ideal single-point diamond turning marks diffraction action model to quantitatively analyze the impact of turning marks diffraction on imaging quality degradation is proposed. Based on this model, a fast estimation algorithm for the optical modulation transfer function of the system under turning marks diffraction (TMTF) is proposed. The results show that the TMTF algorithm achieves high computational accuracy, with a relative error of only 3% in diffraction efficiency, while being hundreds of times faster than rigorous coupled wave analysis (RCWA). This method is significant for reducing manufacturing costs and improving production efficiency, as it avoids the problem of being unable to compute large-size optical systems due to computational resource and time constraints.

Sub-nanometer finishing of polycrystalline tin by inductively coupled plasma-assisted cutting

Polycrystalline tin is an ideal excitation material for extreme ultraviolet light sources. However, the existence of grain boundary (GB) limits the surface roughness of polycrystalline tin after single-point diamond turning (SPDT). In this work, a novel method termed inductively coupled plasma (ICP)-assisted cutting was developed for the sub-nanometer finishing of polycrystalline tin. The relationship between ICP power, processing time, and modification depth was established by thermodynamic simulation, and the fitted heat transfer coefficient of polycrystalline tin was 540 W/(m2·K). The effects of large-thermal-gradient ICP treatment on the microstructure of polycrystalline tin were studied. After 0.9 kW ICP processing for 3.0 s, corresponding to the temperature gradient of 0.30 K/µm, the grain size of polycrystalline tin was expanded from a size of approximately 20–80 µm to a millimeter scale. The Taguchi method was used to investigate the effects of rotational speed, depth of cut, and feed rate on SPDT. Experiments conducted based on the ICP system indicated that the plasma-assisted cutting method promoted the reduction of the influence of GB steps on the finishing of polycrystalline tin, thereby achieving a surface finish from 8.53 to 0.80 nm in Sa. The results of residual stress release demonstrated that the residual stress of plasma-assisted turning processing after 504 h stress release was 10.7 MPa, while that of the turning process without the ICP treatment was 41.6 MPa.

Nano-Precision Processing of NiP Coating by Magnetorheological Finishing.

NiP coating has excellent physicochemical properties and is one of the best materials for coating optical components. When processing NiP coatings on optical components, single-point diamond turning (SPDT) is generally adopted as the first process. However, SPDT turning produces periodic turning patterns on the workpiece, which impacts the optical performance of the component. Magnetorheological finishing (MRF) is a deterministic sub-aperture polishing process based on computer-controlled optical surface forming that can correct surface shape errors and improve the surface quality of workpieces. This paper analyzes the characteristics of NiP coating and develops a magnetorheological fluid specifically for the processing of NiP coating. Based on the basic Preston principle, a material removal model for the MRF polishing of NiP coating was established, and the MRF manufacturing process was optimized by orthogonal tests. The optimized MRF polishing process quickly removes the SPDT turning tool pattern from the NiP coating surface and corrects surface profile errors. At the same time, the surface quality of the NiP coating has also been improved, with the surface roughness increasing from Ra 2.054 nm for SPDT turning to Ra 0.705 nm.

저마늄 소재의 초정밀가공공정을 통한 표면특성분석 및 스포크형상 결함제거

Germanium, an optical material, has high transmittance and refractive index and low light scattering in the infrared region, and research is being conducted to utilize it in various industrial fields. Various forms of optical lenses can be subjected to ultra-precision machining with high quality surface roughness, and they form accuracy through single point diamond turning (SPDT). In particular, the diamond tool with a negative rake angle and the u-LAM process that applies a 1,064 nm laser to the material have been studied to fabricate brittle materials into optical lenses. In this study, the effects of process parameters, such as laser power (W), spindle speed (RPM), feed rate (mm/min), and depth of cut (μm), on the surface roughness of a sub-nanometer scale and the occurrence of defects during the machining process were analyzed for Germanium materials. The process of removing these defects was also analyzed.