Optimising the Process Conditions in Ultra-Precision Grinding to Achieve Surface Finish of Optical Quality

2006 ◽  
Vol 304-305 ◽  
pp. 8-13 ◽  
Author(s):  
T. Jin ◽  
D.J. Stephenson
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Material Removal ◽  
Removal Rate ◽  
Optical Quality ◽  
Process Conditions ◽  
Low Alloy Steel ◽  
Optical Surface ◽  
Precision Grinding ◽  
Ultra Precision

Optical surface finish below Ra 10nm can be achieved on a ‘Tetraform C’ grinder of ultra-high stiffness, when grinding a low alloy steel with or without the help of ELID (electrolytic in process dressing). Surface roughness generation modelling has been carried out to predict thepossible surface roughness values. Efforts have been made to transfer the process knowledge to different grinding mode using a rigid 5-axis Edgetek CNC grinder. The effects of material removal rate and grit size and also that of spark out passes on the surface roughness generated have been investigated.

High-Throughput Picosecond Laser Machining of Aerospace Nickel Superalloy

2021 ◽  
pp. 095440542110288
Author(s):  
Sundar Marimuthu ◽  
Bethan Smith
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
Thermal Damage ◽  
Removal Rate ◽  
Picosecond Laser ◽  
Nickel Superalloy ◽  
Laser Machining ◽  
Process Conditions ◽  
Machining Performance

This manuscript discusses the experimental results on 300 W picosecond laser machining of aerospace-grade nickel superalloy. The effect of the laser’s energetic and beam scanning parameters on the machining performance has been studied in detail. The machining performance has been investigated in terms of surface roughness, sub-surface thermal damage, and material removal rate. At optimal process conditions, a picosecond laser with an average power output of 300 W can be used to achieve a material removal rate (MRR) of ∼140 mm3/min, with thermal damage less than 20 µm. Shorter laser pulse widths increase the material removal rate and reduce the resultant surface roughness. High scanning speeds improve the picosecond laser machining performance. Edge wall taper of ∼10° was observed over all the picosecond laser machined slots. The investigation demonstrates that high-power picosecond lasers can be used for the macro-machining of industrial components at an acceptable speed and quality.

Comparison of Processing Features between Semi Bonded Abrasive Lapping and Loose Abrasive Lapping

2009 ◽  
Vol 416 ◽  
pp. 439-442
Author(s):  
Xun Lv ◽  
Ju Long Yuan ◽  
Dong Hui Wen
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Processing Parameters ◽  
Good Surface ◽  
Ultra Precision ◽  
New Processing ◽  
Short Time

Semi bonded abrasive lapping is an effective ultra-precision lapping method. It can obtain good surface quality of workpiece in short time. This paper focused on the differences of processing features by comparing semi bonded abrasive lapping and loose abrasive lapping in several groups processing parameters. The results showed that the surface roughness of workpiece in semi bonded abrasive lapping was far superior to that of loose abrasive lapping in same processing parameters. And the MRR (material removal rate) of semi bonded abrasive lapping was slightly lower than that of loose abrasive lapping. For these features of semi bonded abrasive, a new processing flow would also be proposed in this paper.

Grinding of Chromium Carbide Coatings Using Electroplated Diamond Wheels

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Zhongde Shi ◽  
Amr Elfizy ◽  
Helmi Attia ◽  
Gilbert Ouellet
Keyword(s):  
Surface Roughness ◽  
Chromium Carbide ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Depth Of Cut ◽  
Process Conditions ◽  
Carbide Coatings ◽  
Grinding Power ◽  
Chromium Carbide Coatings

This paper reports an experimental study on grinding of chromium carbide coatings using electroplated diamond wheels. The work was motivated by machining carbide coatings in gas turbine engine applications. The objective is to explore the process conditions and parameters satisfying the ground surface quality requirements. Surface grinding experiments were conducted with water-based grinding fluid on chromium carbide coated on flat surfaces of aluminum blocks for rough grinding at a fixed wheel speed vs = 30 m/s, and finish grinding at vs = 30, 60 m/s. The effects of depth of cut and workspeed on grinding power, forces, and surface roughness were investigated for each of the wheel speeds. Material removal rate Q = 20 mm3/s for rough grinding at a grinding width b = 101.6 mm was achieved. It was found that the maximum material removal rate achievable in rough grinding was restricted by chatters, which was mainly due to the large grinding width. The specific energy ranged from 27 to 59 J/mm3 under the tested conditions. Surface roughness Ra = 3.5–3.8 μm were obtained for rough grinding, while Ra = 0.6–1.5 μm were achieved for finish grinding. Surface roughness was not sensitive to grinding parameters under the tested conditions, but was strongly dependent on the diamond grain sizes. Imposing axial wheel oscillations to the grinding motions reduced surface roughness by about 60% under the tested condition. It was proved that it is feasible to grind the chromium carbide coating with electroplated diamond wheels.

Study on Precision Polishing of a Mini Roller Mold

2010 ◽  
Vol 126-128 ◽  
pp. 551-556
Author(s):  
Choung Lii Chao ◽  
Ying Ching Hsiao ◽  
Wen Chen Chou ◽  
Chia Wei Kuo ◽  
Wen Lang Lai ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Surface Finish ◽  
Empirical Model ◽  
Material Removal ◽  
Removal Rate ◽  
Surface Condition ◽  
Microscopic Analysis ◽  
Semi Empirical ◽  
Better Than

This research aimed to design and develop a polishing system for precision polishing mini roller mold to nanometer surface finish. An experimental polishing system was built in the present study to polish nickel plated specimens with various polishing compounds. The polished specimens were subsequently examined by Alfa-step, OM and SEM for surface finish, morphology and microscopic analysis respectively. The obtained surface condition and material removal rate were correlated to the polishing parameters such as spindle speed, abrasive concentration, and abrasive grit size for the improvement of the polishing effect. Mini-rollers of 5mm in diameter, 50mm in length were successfully polished to a surface roughness better than 2nm Ra in several hours without damaging the roundness and cylindricalness using abrasive of 0.3μm, 10,000rpm polishing speed and 0.5mm gap distance between polisher and the specimen. A semi-empirical model of polishing was also developed in the study for predicting the materials removal rate.

scholarly journals Effect of the Lapping Platen Groove Density on the Characteristics of Microabrasive-Based Lapping

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 775
Author(s):  
Taekyung Lee ◽  
Haedo Jeong ◽  
Sangjik Lee ◽  
Doyeon Kim ◽  
Hyoungjae Kim
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Material Removal ◽  
Removal Rate ◽  
High Surface ◽  
Abrasive Particle ◽  
Process Conditions ◽  
Abrasive Particles ◽  
Oil Film ◽  
Process Characteristics

Microabrasive-based lapping is widely used in the manufacturing of single-crystal substrates such as sapphire, SiC, and GaN. Although many studies have been conducted to improve the lapping process characteristics, most of them focused on process conditions or consumables. In this study, the effect of the lapping platen groove density on the lapping characteristics was studied using a sapphire substrate. Groove density was defined as the ratio of groove width to groove pitch, and the displacement of the lapping head was measured to calculate the oil film thickness. It was confirmed that, for groove densities below 0.30, hydroplaning occurs when the oil film thickness increases. When the oil film thickness is larger than the abrasive particle size, the material removal rate is low because the abrasive does not participate in the lapping process. When the oil film was developed, the experimental results showed a high surface roughness and poor flatness of the substrate, as only large abrasive particles participated in the lapping process. Therefore, to improve the lapping characteristics, it is important to reduce the groove density by reducing the groove pitch, which prevents the development of the oil film.

Dressing of Monolayer Brazed Diamond Wheel for Grinding Li-Ti Ferrite

2010 ◽  
Vol 126-128 ◽  
pp. 995-1000 ◽  
Author(s):  
Hong Hua Su ◽  
Yu Can Fu ◽  
Jiu Hua Xu ◽  
Wen Feng Ding ◽  
Hong Jun Xu
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Removal Rate ◽  
Ground Surface ◽  
Diamond Wheel ◽  
Substantial Improvement ◽  
Precision Grinding ◽  
High Roughness ◽  
Grinding Operations ◽  
Ground Surface Roughness

The monolayer brazed diamond tools have recently been used increasingly in hard-brittle materials grinding because of their excellent grinding performances as long tool life, high material removal rate and large inter-grit chip space, etc. However, they possess an inherent shortcoming of the high roughness of the grinding surface. This work is an attempt to reduce the over-protruded grits of the monolayer brazed diamond wheel so that precision grinding operations can be executed effectively. In this investigation, the monolayer brazed diamond wheels with regular distribution pattern of grit have been dressed by a special conditioning process and used in precision grinding experiments on Li-Ti ferrite. The outcome of this attempt appeared highly encouraging. A substantial improvement of the ground surface roughness could be achieved with the dressed monolayer brazed diamond wheels.

Genetic Programming for Grinding Surface Roughness Modelling

2012 ◽  
Vol 565 ◽  
pp. 183-189
Author(s):  
Xun Chen ◽  
Asma Alabed
Keyword(s):  
Surface Roughness ◽  
Genetic Programming ◽  
Material Removal Rate ◽  
Surface Finish ◽  
Material Removal ◽  
Removal Rate ◽  
High Accuracy ◽  
Grinding Process ◽  
Reliable Prediction ◽  
Modelling Process

Grinding process is commonly selected for finishing operation because grinding has high accuracy and surface finish with a relatively high material removal rate. One of the most common issues in grinding process planning is to determine grinding condition for required surface roughness. This paper presents a feasibility study on grinding surface roughness modelling using genetic programming (GP) method. It has successfully demonstrated that GP could provide reliable prediction and has advantages over other established methods in terms of dealing with missing data during modelling process.

Study of the Cutting Parameters on Surface Roughness and Material Removal Rate in Hard Turning of UHMWPE

2020 ◽  
Author(s):  
César Oswaldo Aguilera-Ojeda ◽  
Alberto Saldaña-Robles ◽  
Agustín Vidal-Lesso ◽  
Israel Martínez-Ramírez ◽  
Eduardo Aguilera-Gómez
Keyword(s):  
Surface Roughness ◽  
Predictive Model ◽  
Material Removal Rate ◽  
Surface Finish ◽  
Material Removal ◽  
Removal Rate ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Turning Process

Abstract The surface finish of industrial components has an important role in their performance and lifetime. Therefore, it is crucial to find the cutting parameters that provide the best surface finish. In this work, an experimental study of the effect of cutting parameters on ultra-high molecular weight polyethylene (UHMWPE) by a turning process was carried out. Today, the UHMWPE polymer continues to find applications mainly in the automotive industry and biomechanics because it is resistant to impact and corrosive materials to use. A face-centered Central Composite Design (CCD) and Response Surface Methodology (RSM) were applied to evaluate the influence of the cutting speed (Vc), feed rate (f) and depth of cut (ap) of the turning operation on the Average Surface Roughness (Ra) and Material Removal Rate (MRR). Results allowed obtaining an adjusted multivariable regression model that describes the behavior of the Ra that depends on the cutting parameters in the turning process. The predictive model of Ra showed that it fits well with a correlation coefficient (R2) around 0.9683 to the experimental data for Ra. The ANOVA results for Ra showed that the feed is the most significant factor with a contribution of 42.3 % for the term f 2, while the speed and depth of cut do not affect Ra with contributions of 0.19% and 0.18%, respectively. A reduction of feed from 0.30 to 0.18 mm·rev−1 produces a decrease in surface roughness from 6.68 to 3.81 μm. However, if the feed continued to reduce an increase in surface roughness, a feed of 0.05 mm·rev−1 induces a surface roughness of 14.93 μm. Feeds less than 0.18 mm·rev−1 cause a heat generation during turning that increases the temperature in the process zone, producing surface roughness damage of the UHMWPE polymer. Also, the results for MRR demonstrated that all of the cutting parameters are significant with contributions of 31.4%, 27.4% and 15.4% to feed, speed, and depth of cut, respectively. The desirability function allowed optimizing the cutting parameters (Vc = 250 m·min−1, ap = 1.5 mm y f = 0.27 mm·rev−1) to obtain a minimum surface roughness (Ra = 4.3 μm) with a maximum material removal rate (MMR = 97.1 cm3·min−1). Finally, the predictive model of Ra can be used in the industry to obtain predictions on the experimental range analyzed, reducing the surface roughness and the manufacturing time of UHMWPE cylindrical components.

New Tool Concepts for Ultra-Precision Grinding

2012 ◽  
Vol 516 ◽  
pp. 287-292 ◽  
Author(s):  
Ekkard Brinksmeier ◽  
Yildirim Mutlugünes ◽  
Grigory Antsupov ◽  
Kai Rickens
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Surface Finish ◽  
Cvd Diamond ◽  
Coarse Grained ◽  
Grinding Wheels ◽  
Precision Grinding ◽  
Diamond Grinding ◽  
Ultra Precision ◽  
Sharp Edges

This paper presents advanced tools for ultra precision grinding which offer a high wear resistance and can be used to generate high-quality parts with an ultraprecise surface finish. The first approach features defined dressed, coarse-grained, single layered, metal bonded diamond grinding wheels. These grinding wheels are called Engineered Grinding Wheels and have been dressed by an adapted conditioning process which leads to uniform abrasive grain protrusion heights and flattened grains. This paper shows the results from grinding optical glasses with such Engineered Grinding Wheels regarding the specific forces and the surface roughness. The results show that the cutting mechanism turns into ductile removal and optical surfaces are achievable. On the other hand, the specific normal force F´n increases due to increased contact area of the flattened diamond grains. It is shown that the topography of the Engineered Grinding Wheels has a strong beneficial influence on surface roughness. The second new tool for ultra precision grinding is made of a CVD (Chemical Vapour Deposition) poly-crystalline diamond layer with sharp edges of micrometre-sized diamond crystallites as a special type of abrasive. The sharp edges of the crystallites act as cutting edges which can be used for grinding. It is shown that by using CVD-diamond-coated grinding wheels a high material removal rate and a high surface finish with surface roughness in the nanometre range can be achieved. The CVD-diamond layers exhibit higher wear resistance compared to conventional metal and resin bonded diamond wheels. In conclusion, this paper shows that not only conventional fine grained, multi-layered resinoid diamond grinding wheels but also coarse-grained and binderless CVD-coated diamond grinding wheels can be applied to machine brittle and hard materials by ultra precision grinding.

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