scholarly journals Morphological Analysis of KDP-Crystal Workpiece Surfaces Machined by Ultra-Precision Fly Cutting

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 432 ◽  
Author(s):  
Dongju Chen ◽  
Shiwei Zhang ◽  
Jingfang Liu ◽  
Chunqing Zha ◽  
Ri Pan
Keyword(s):  
Influencing Factor ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Machined Surface ◽  
Fractal Method ◽  
Kdp Crystal ◽  
Power Spectral ◽  
Ultra Precision ◽  
The Relationship ◽  
Machined Surfaces

Potassium dihydrogen phosphate crystals exhibit excellent nonlinear optical properties that are significantly affected by the surface morphology of the crystal. To comprehensively examine and characterize the morphological features of these crystals, the machined surfaces of workpieces are analyzed using wavelet, fractal, and power spectral density (PSD) methods. First, the fractal method is employed to analyze the features of the machined surfaces of different materials and examine the relationship between the surface roughness and fractal dimension of different materials. Then, the morphological anisotropy of the machined surfaces is analyzed using the two-dimensional PSD method. Based on the orientation of the machined surfaces of the workpieces, the tangential waves on the surfaces are analyzed using wavelet-transform and PSD methods. From a frequency-domain perspective, the scales of various influencing factor signals are identified. Additionally, the frequency range of the spindle vibration is determined based on the machining experiment. On this basis, the cause of the machined surface waviness errors is revealed.

Investigation on the influence of aerostatic pressure upon surface generation in flycutting

2018 ◽  
Vol 233 (4) ◽  
pp. 1136-1143 ◽  
Author(s):  
Congying Deng ◽  
Chenhui An ◽  
Bo Wei ◽  
Jianguo Miao
Keyword(s):  
Single Point ◽  
Complex Structure ◽  
Pressure Fluctuations ◽  
Potassium Dihydrogen Phosphate ◽  
Axial Direction ◽  
Surface Generation ◽  
Dihydrogen Phosphate ◽  
Machined Surface ◽  
Potassium Dihydrogen ◽  
The Relationship

Single-point diamond flycutting is an important technology for cutting flat KH2PO4 (potassium dihydrogen phosphate) crystals of large size. However, there always exist some undesirable waviness errors on the machined surface, which can directly reduce the optical performance of the potassium dihydrogen phosphate crystals. This article presents a kind of low-frequency waviness errors with wavelength about 26 mm along the feeding direction in single-point diamond flycutting, which has not been described yet. In order to find the main source of the mentioned waviness errors, the relationship between the displacement of the cutting tool and the aerostatic pressure was quantitatively studied for the first time. And then, surface simulation considering the aerostatic pressure fluctuations was carried out based on the relationship. Besides, a novel method that can achieve online submicron feeding along axial direction in single-point diamond flycutting without complex structure was proposed considering the spindle motion errors, the spindle dynamic characteristics and the aerostatic pressure. The experimental results validate that the mentioned waviness errors are mainly generated by the bolt stretched phenomenon and deformation of the big disk flycutting head due to the aerostatic pressure fluctuations. And the proposed method can achieve a cutting depth of about 120 nm when the aerostatic pressure increases from 0.52 to 0.56 MPa, which can reduce the cutting force and is beneficial for the performance of single-point diamond flycutting.

scholarly journals Research on the Relationship between Cutting Force and Machined Surface Quality in Micro Ball End-Milling of Potassium Dihydrogen Phosphate Crystal

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 574
Author(s):  
Ni Chen ◽  
Chunya Wu ◽  
Mingjun Chen ◽  
Liang Li ◽  
Ning He
Keyword(s):  
Cutting Force ◽  
Thrust Force ◽  
End Milling ◽  
Potassium Dihydrogen Phosphate ◽  
Spindle Speed ◽  
Dihydrogen Phosphate ◽  
Dimensional Error ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
The Relationship

Potassium dihydrogen phosphate (KDP or KH2PO4) crystal is widely used as terminal frequency converters in inertial confinement fusion (ICF). However, KDP crystal is a typical difficult-to-cut optical crystal with the characteristic of soft-brittle. In this work, the relationship between cutting force and processed surface quality in micro ball end-milling of KDP crystal with various depth of cut and spindle speed is studied by carried out the micro-milling experiments. Fast Fourier Transform (FFT) algorithm is used to diagnose the recorded cutting force. The periodic change of cutting force and the cutting force after filtering noises can be got through FFT analysis. Through calculating the correlation coefficients between the static component of thrust force and roughness value Ra of machined grooves, as well as the peak-valley (P-V) value of thrust force and dimensional error of machined grooves, the roughness value Ra and dimensional error of machined grooves would be predicted by monitoring the static component and P-V value of the thrust force, respectively. The relatively large spindle speed helps to reduce the roughness value Ra. The spindle speed with moderate value is recommended to reduce the dimensional error of machined groove because the dimensional error of machined groove will increase when the spindle speed is small enough (causing brittle cutting) or large enough (reducing cutting stability).

Experimental Study on Micro-Deliquescence Ultra-Precision Polishing with Fine Water Mist for KDP Crystal

2013 ◽  
Vol 797 ◽  
pp. 423-427 ◽  
Author(s):  
Xu Wang ◽  
Hang Gao ◽  
Dong Ming Guo ◽  
Y.C. Chen ◽  
C.P. Song
Keyword(s):  
Experimental Study ◽  
Potassium Dihydrogen Phosphate ◽  
Water Mist ◽  
Precision Machining ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Ultra Precision ◽  
Polishing Tool

KDP crystal (Potassium dihydrogen phosphate single crystal) is extremely difficult to obtain flawless surface because of its soft, brittle, and hygroscopic. And a large amount of time has been spend on obtaining flawless surface with ultra-precision machining methods. In order to quickly reduce surface roughness on KDP crystal, a new micro-deliquescence polishing method with fine water mist was proposed, the polishing tool with fine water mist was designed, and the polishing experiment was carried out. The micro-deliquescence polishing with fine water mist can improve the surface quality of KDP crystal quickly, so it is an effective preprocessing before ultra-precision machining.

scholarly journals Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals: characterization by nanoindentation

2020 ◽  
Vol 8 (4) ◽  
pp. 447-456
Author(s):  
Yong Zhang ◽  
Ning Hou ◽  
Liang-Chi Zhang ◽  
Qi Wang
Keyword(s):  
Plastic Deformation ◽  
Brittle Fracture ◽  
Optical Switching ◽  
Potassium Dihydrogen Phosphate ◽  
Machining Process ◽  
Fracture Mechanisms ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Kdp Crystals

AbstractPotassium dihydrogen phosphate (KDP) crystals are widely used in laser ignition facilities as optical switching and frequency conversion components. These crystals are soft, brittle, and sensitive to external conditions (e.g., humidity, temperature, and applied stress). Hence, conventional characterization methods, such as transmission electron microscopy, cannot be used to study the mechanisms of material deformation. Nevertheless, understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process. This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations. The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals, and dislocation pileup leads to brittle fracture during nanoindentation. Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals, and plastic deformation and brittle fracture are related to the material’s anisotropy. However, the effect of loading rate on the KDP crystal deformation is practically negligible. The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.

scholarly journals Novel abrasive-free jet polishing mechanism for potassium dihydrogen phosphate (KDP) crystal

2018 ◽  
Vol 8 (4) ◽  
pp. 1012 ◽  
Author(s):  
Wei Gao ◽  
Lili Wang ◽  
Lunfu Tian ◽  
Pengfei Sun ◽  
Hui Dong ◽  
...  
Keyword(s):  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Free Jet

A Study of Potassium Dihydrogen Phosphate (KDP) Crystal Surfaces by XPS

2001 ◽  
Vol 8 (1) ◽  
pp. 56-80 ◽  
Author(s):  
Mark Engelhard ◽  
Cheryl Evans ◽  
T. A. Land ◽  
A. J. Nelson
Keyword(s):  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Crystal Surfaces ◽  
Kdp Crystal ◽  
Potassium Dihydrogen

Measurement of quadratic electrogyration effect in KDP crystals for light propagating along the optical axis

2019 ◽  
Vol 52 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Marek Izdebski
Keyword(s):  
Optical Axis ◽  
Potassium Dihydrogen Phosphate ◽  
High Sensitivity ◽  
Measurement Procedure ◽  
Measuring System ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Electro Optic ◽  
Lock In

In this paper, a method of measuring the β31 coefficient of the quadratic electrogyration effect in potassium dihydrogen phosphate (KDP)-type crystals is proposed. It is shown that this very weak effect can be decoupled from other stronger effects occurring simultaneously in the real measuring system, even when small inaccuracies in crystal cutting and alignment are taken into account. Theoretical and numerical analyses are illustrated by experimental data obtained for the KDP crystal. High sensitivity, which is required for successful measurements at room and higher temperatures, has been achieved by using the polarimetric method for a light beam propagating along the optical axis of the crystal in combination with the lock-in technique and a new measurement procedure that compensates for the contribution of other effects such as electro-optic effects, natural birefringence and dichroism. It was found that the β31 coefficient measured at a wavelength of 632.8 nm decreases linearly from 2.53 × 10−21 m2 V−2 at a temperature of 298 K to 2.08 × 10−21 m2 V−2 at 343 K.

Research on Deliquescent Polishing Fluid for KDP Crystals

2009 ◽  
Vol 626-627 ◽  
pp. 53-58 ◽  
Author(s):  
Shao Long Guo ◽  
Fei Hu Zhang ◽  
Yong Zhang ◽  
Dian Rong Luan
Keyword(s):  
Removal Rate ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Performance Requirements ◽  
Stability Experiment ◽  
Main Components ◽  
Polishing Fluid ◽  
Kdp Crystals

The characteristics and principle of deliquescent polishing technology for potassium dihydrogen phosphate (KDP) crystals are introduced, and the performance requirements of deliquescent polishing fluid for KDP crystals are proposed. The main components of the deliquescent polishing fluid for KDP crystals were selected according to these performance requirements. Through uniformity experiment, stability experiment and fluidity experiment, uniformity, stability and fluidity of deliquescent polishing fluid for KDP crystals prepared using the selected components were tested. Through deliquescent polishing experiment of KDP crystal, polishing performance of deliquescent polishing fluid compounded using the selected components was tested. The material removal rate of the KDP crystal in the deliquescent polishing experiment was 6.03μm/min, and the surface roughness of the KDP crystal after deliquescent polishing was 4.857nm. The experimental results show that the compounded deliquescent polishing fluid for KDP crystals has good polishing performance and can reach the requirements.

Research on Influence of Crystal KDP Anisotropy on Critical Condition of Brittle-Ductile Transition in Ultra-Precision Cutting

2006 ◽  
Vol 315-316 ◽  
pp. 725-730 ◽  
Author(s):  
Ming Jun Chen ◽  
Ying Chun Liang ◽  
Jing He Wang ◽  
Shen Dong
Keyword(s):  
Surface Quality ◽  
Critical Condition ◽  
Influence Factors ◽  
Potassium Dihydrogen Phosphate ◽  
Experimental Results ◽  
Depth Of Cut ◽  
Dihydrogen Phosphate ◽  
Brittle Ductile Transition ◽  
Ultra Precision

In order to machine high accuracy Potassium Dihydrogen Phosphate (KDP) crystal part, the indentation experiments are carried out with various loads and various orientation angles. The experimental results show that the critical condition of brittle-ductile transition of KDP has strong anisotropy. Therefore, the influence factors on the surface quality of crystal KDP was discussed, it is shown that influences of the tool's geometry parameter, feed rate and Nominal depth of cut etc on the surface quality of KDP are main. Afterwards the cutting experimental study on crystal KDP material is carried out. The experimental results show that the super-smooth surface quality only can be obtained while KDP is ultra-precision machined in ductile mode.

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