Prediction of Surface Profile Evolution of Workpiece and Lapping plate in Lapping Process

2021 ◽  
pp. 1-34
Author(s):  
Zhichao Geng ◽  
Ping Zhou ◽  
Lei Meng ◽  
Ying Yan ◽  
Dongming Guo
Keyword(s):  
Optical Glass ◽  
Removal Rate ◽  
Surface Profile ◽  
Copper Plate ◽  
Modeling Method ◽  
Plate Interface ◽  
Inclination Angles ◽  
Material Removal Rate Model ◽  
The Right ◽  
Evolution Modeling

Abstract Lapping has a history of hundreds of years, yet it still relies on the experience of workers. To improve the automaticity and controllability of the lapping process, a modeling method of friction and wear is developed to predict the surface profile evolution of the workpiece and lapping plate in the lapping process. In the proposed method, by solving the balance equations of resultant force and moment, the inclination angles of the workpiece can be calculated, thus more accurate contact pressure distribution of the workpiece/lapping plate interface can be calculated. Combined with the material removal rate model, the continuous evolution process of the workpiece and lapping plate can be predicted in the lapping process. The modeling method was validated by a lapping test of a flat optical glass (Φ 100 mm) with a composite copper plate. The results show that the proposed method can predict the evolution of the surface profile of the workpiece and lapping plate with high accuracy. Consequently, the lapping plate can be dressed at the right time point. Benefit from this, in the validation test the PV value of the workpiece (with 5 mm edge exclusion) was reduced from 5.279 μm to 0.267 μm in 30 min. The proposed surface profile evolution modeling method not only improves the lapping efficiency but also provides an opportunity to understand the lapping process.

A Global Correction Process for Flat Optics With Patterned Polishing Pad

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Weisi Li ◽  
Ping Zhou ◽  
Zhichao Geng ◽  
Ying Yan ◽  
Dongming Guo
Keyword(s):  
Optical Glass ◽  
Removal Rate ◽  
Surface Profile ◽  
Prediction Method ◽  
Correction Method ◽  
Polishing Process ◽  
Polishing Pad ◽  
Edge Exclusion ◽  
Optics Fabrication ◽  
Surface Figure

To improve the efficiency of flat optics fabrication, a global correction method with the patterned polishing pad is developed in this paper. Through creating grooves on a polishing pad, the contact pressure distribution on the optics surface can be adjusted to change the material removal rate (MRR) distribution during polishing. Using the patterned pad, the selective removal ability of the polishing process is greatly enhanced. The predictability and stability of the MRR distribution are the preconditions to efficiently implement the proposed global correction method. Relying on the MRR distribution prediction method proposed and validated in this paper, the pad pattern can be designed based on the original surface figure of the workpieces. The designed groove pattern is created on the polishing pad using the custom-developed equipment. Then, the optical glass is polished on the designed pad with the optimized polishing time. A flat optical glass sample (Φ 100 mm) is polished with the global correction method to show its feasibility and advantage. The correction instance shows that the peak-to-valley (PV) value of the surface profile (with 3 mm edge exclusion) dropped from 1.17 µm to 0.2 µm in 14 min using a polyurethane pad with two ring grooves. Comparing with the conventional polishing process, which usually takes hours or days, the global correction method proposed in this paper can improve the efficiency of the optics manufacturing significantly.

scholarly journals Surface Evolution During Semiconductor Processing

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 379-384 ◽  
Author(s):  
Ganesh Rajagopalan ◽  
Vadali Mahadev ◽  
Timothy S. Cale
Keyword(s):  
Riemann Problem ◽  
Surface Profile ◽  
Numerical Implementation ◽  
Jump Conditions ◽  
Semiconductor Processing ◽  
Explicit Integration ◽  
Surface Evolution ◽  
Left And Right ◽  
The Right ◽  
Surface Angle

We discuss our approach to using the Riemann problem to compute surface profile evolution during the simulation of deposition, etch and reflow processes. Each pair of segments which represents the surface is processed sequentially. For cases in which both segments are the same material, the Riemann problem is solved. For cases in which the two segments are different materials, two Riemann problems are solved. The material boundary is treated as the right segment for the left material and as the left segment for the right material. The critical equations for the analyses are the characteristics of the Riemann problem and the ‘jump conditions’ which represent continuity of the surface. Examples are presented to demonstrate selected situations. One limitation of the approach is that the velocity of the surface is not known as a function of the surface angle. Rather, it is known for the angles of the left and right segments. The rate as a function of angle must be assumed for the explicit integration procedure used. Numerical implementation is briefly discussed.

Parametric Study of Micro Machining Three Dimensional Microstructure with the Tiny-Grinding Wheel Based on the EMR Effect

2010 ◽  
Vol 447-448 ◽  
pp. 193-197
Author(s):  
Wei Qiang Gao ◽  
Qiu Sheng Yan ◽  
Yi Liu ◽  
Jia Bin Lu ◽  
Ling Ye Kong
Keyword(s):  
Magnetic Field ◽  
Material Removal Rate ◽  
Feed Rate ◽  
Material Removal ◽  
Rotation Speed ◽  
Optical Glass ◽  
Removal Rate ◽  
Grinding Wheel ◽  
Machining Time ◽  
Fluctuation Phenomenon

Electro-magneto-rheological (EMR) fluids, which exhibit Newtonian behavior in the absence of a magnetic field, are abruptly transformed within milliseconds into a Bingham plastic under an applied magnetic field, called the EMR effect. Based on this effect, the particle-dispersed EMR fluid is used as a special instantaneous bond to cohere abrasive particles and magnetic particles together so as to form a dynamical, flexible tiny-grinding wheel to machine micro-groove on the surface of optical glass. Experiments were conducted to reveal the effects of process parameters, such as the feed rate of the horizontal worktable, feeding of the Z axis, machining time and machining gap, on material removal rate of glass. The results indicate that the feed rate of the worktable at horizontal direction has less effect on material removal rate, which shows a fluctuation phenomenon within a certain range. The feed rate of the Z axis directly influences the machining gap and leads to a remarkable change on material removal rate. Larger material removal rate can be obtained when the feeding frequency of Z direction is one time per processing. With the increase of rotation speed of the tool, material removal rate increases firstly and decreases afterwards, and it gets the maximum value with the rotation speed of 4800 rev/min. The machining time is directly proportional to material removal amount, but inversely proportional to material removal rate. Furthermore, material removal rate decreases with the increase of the machining gap between the tool and the workpiece. On the basis of above, the machining mode with the tiny-grinding wheel based on the EMR effect is presented.

Numerical Simulation and Experimental Validation of Pure Water Jet Machining of Ti-6Al-4V

2020 ◽  
Author(s):  
Greg Pasken ◽  
J. Ma ◽  
Muhammad P. Jahan ◽  
Shuting Lei
Keyword(s):  
Predictive Modeling ◽  
Metal Cutting ◽  
Removal Rate ◽  
Pure Water ◽  
Surface Profile ◽  
Predictive Modelling ◽  
Water Jet ◽  
The Other ◽  
Orifice Diameter ◽  
Cutting Processes

Abstract The most common problem when machining titanium using traditional metal cutting processes is that tools rapidly wear out and need to be replaced. This study examines the ability of a pure water jet to machine Ti-6Al-4V via simulations using ABAQUS’s Smoothed Particle Hydrodynamics (SPH). These simulations are then validated experimentally at two pressures, 138 MPa and 317 MPa. Using a Maxiem water jet built by Omax, experiments are conducted by creating a series of 5 lines that are 5 inches (127 mm) long placed 0.5 inches (12.7 mm) apart on a 1 mm thick Ti-6Al-4V workpiece. Predictive modeling is also conducted using the two additional pressures 400 MPa and 621 MPa as well as three orifice diameters 0.254 mm, 0.3556 mm, and 0.4572 mm. The simulations are validated at both pressures and had a percent error less than 2.6% which were within the standard deviation of the experimental results. The predictive modeling indicates that the pressures above 317 MPa create a near identical percent increase from the orifice diameter but the kerf has a more noticeable decrease in width of cut as the pressure increases. The 138 MPa has the smoothest surface profile compared to the other pressures. The volume of removed material decreases as the pressure increases but the material removal rate (MRR) increases as the pressure increases. This is due to the velocity of the water increasing as the pressure increases causing a lower run time. The 621 MPa is the best pressure to machine Ti-6Al-4V as it has a better MRR than the other pressures used in the predictive modelling.

Effects of the Profile of Workpiece Surface on Material Removal Rate Distribution in Polishing Process

2016 ◽  
Vol 851 ◽  
pp. 149-154
Author(s):  
Zhen Gang Wu ◽  
Dong Shan He ◽  
Ping Zhou ◽  
Dong Ming Guo
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Surface Profile ◽  
Prediction Method ◽  
Quantitative Prediction ◽  
Polishing Process ◽  
Workpiece Surface ◽  
Coefficient Distribution ◽  
Polishing Pad

Accurate prediction of the material removal rate (MRR) distribution is very important for the control of the polishing process. However, the widely used prediction method of MRR based on the Preston equation is still incapable of predicting the roll-off phenomenon in polishing process. One of the reasons is that many of the researchers’ neglected the effect of the surface profile of the workpiece on the MRR. In this paper, the evolutionary process of MRR distribution with the change of surface profile using two different polishing pad is studied, it is found that MRR varies gradually with the change of surface profile and tends to be uniform finally. Based on the analysis of contact pressure considering the actual surface profile of workpiece and modified Preston equation, the distribution of MRR is analyzed. It is found that the Preston coefficient distribution on workpiece surface is stable when the surface profile variation is small and shows obvious differences from the center to the edge of the workpiece. Through the comparison it is found that correlation between the regularities of Preston coefficient distribution and the type of polishing pad is significant. The research results in this paper will play an important guiding role in the quantitative prediction method research of polishing process.

Material Removal Model and Experimental Verification for Abrasive Jet Precision Finishing with Wheel as Restraint

2006 ◽  
Vol 304-305 ◽  
pp. 555-559 ◽  
Author(s):  
Chang He Li ◽  
Guang Qi Cai ◽  
Shi Chao Xiu ◽  
Q. Li
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Experimental Results ◽  
Grinding Wheel ◽  
Rate Model ◽  
Material Removal Model ◽  
Material Removal Rate Model ◽  
Three Body ◽  
Precision Finishing

The material removal rate (MRR) model was investigated in abrasive jet precision finishing (AJPF) with wheel as restraint. When abrasive wore and workpiece surface micro-protrusion removed, the size ratio for characteristic particle size to minimum film thickness gradually diminishing, the abrasive machining from two-body lapping to three-body polishing transition in AJPF with grinding wheel as restraint. In the study, the material removal rate model was established according to machining mechanisms and machining modes from two-body to three-body process transition condition, and active number of particles in grinding zone were calculated and simulated. Experiments were performed in the plane grinder for material removal mechanism and academic models verification. It can be observed from experimental results that the surface morphology change dramatically to a grooved or micro-machined surface with all the grooves aligned in the sliding direction in two-body lapping mode. On the other hand, the surface is very different, consists of a random machining pits with very little sign of any directionality to the deformation in the three-body machining mode. Furthermore, the material removal rate model was found to give a good description of the experimental results.

Influence of Abrasive on Planarization Grinding Based on the Cluster Magnetorheological Effect

2011 ◽  
Vol 325 ◽  
pp. 542-547
Author(s):  
Qiu Sheng Yan ◽  
Jie Wen Yan ◽  
Jia Bin Lu ◽  
Wei Qiang Gao ◽  
Min Li
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Optical Glass ◽  
Removal Rate ◽  
Mr Fluid ◽  
Grinding Method ◽  
Magnetorheological Effect ◽  
The Difference ◽  
Mr Effect

A new planarization grinding method based on the cluster magnetorheological (MR) effect is presented to grind optical glass in this paper. Some process experiments were conducted to reveal the influence of the species and granularity and content of the abrasive materials in the MR fluid on the machining effect, furthermore, the machining characteristic of grinded surface was studied. The results indicate that the abrasive influences definitively on machining effect of this planarization grinding method based on the cluster MR-effect. Under the certain experiment condition, with the content of the abrasive 10% and grain size 800# of SiC, best machining effect can be achieved. The difference species of abrasive results in various machining effects. As for the removal rate of K9 optical glass: abrasive CeO2 is the best, the Al2O3 is the second and the SiC is the worst. While the surface roughness: abrasive SiC is the lowest，the Al2O3 is the second and CeO2 is the highest.

The Experimental Study on Mechanical Polishing on Materials with Hydrolysis Reaction

2017 ◽  
Vol 739 ◽  
pp. 182-186
Author(s):  
Hung Jung Tsai ◽  
Pay Yau Huang ◽  
Chung Ming Tan ◽  
Tang Feng Chang
Keyword(s):  
Experimental Study ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Hydrolysis Reaction ◽  
Polishing Process ◽  
Surface Polishing ◽  
Material Removal Rate Model

The hydrolytic properties of LiAlO2 (LAO) are important factors for its applications on LED fabrication. During soft pad polishing process, the H2O in the slurry is deleterious for LAO surface polishing results. The current study develops a material removal rate model for materials with hydrolysis reaction to predict the result of polishing process.The current research conducts the experimental studies to investigate the material removal rate and its mechanism during the soft pad polishing process. In the experimental study, the hydrolytic properties of LAO have been tested to understand the hydrolysis speed with different operation parameters to assist the development of the theoretical model. Also the material removal rates of LAO with hydrolytic property have been measured under different soft pad polishing operating conditions. The experimental results provide the hydrolytic properties of LiAlO2 to understanding of the mechanism on polishing process.

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