Magnetorheological (MR) Jet Finishing Technology

2004 ◽  
Author(s):  
William I. Kordonski ◽  
Aric B. Shorey ◽  
Marc Tricard
Keyword(s):  
High Precision ◽  
Material Removal ◽  
High Speed ◽  
Axial Magnetic Field ◽  
Fundamental Property ◽  
Cfd Modeling ◽  
Surface Shear Stress ◽  
Round Jet ◽  
Mr Polishing Fluid ◽  
The Impact

Conformal (or freeform) and steep concave optics are important classes of optics that are difficult to finish using conventional techniques due to mechanical interferences and steep local slopes. One suitable way to polish these classes of optics is by using a jet of abrasive/fluid mixture. In doing so, the energy required for polishing may be supplied by the radial spread of a liquid jet, which impinges a surface to be polished. Such fluid flow may generate sufficient surface shear stress to provide material removal in the regime of chemical mechanical polishing. Once translated into a polishing technique, this unique tool may resolve a challenging problem of finishing steep concave surfaces and cavities. A fundamental property of a fluid jet is that it begins to lose its coherence as the jet exits a nozzle. This is due to a combination of abruptly imposed longitudinal and lateral pressure gradients, surface tension forces, and aerodynamic disturbance. This results in instability of the flow over the impact zone and consequently polishing spot instability. To be utilized in deterministic high precision finishing of remote objects, a stable, relatively high-speed, low viscosity fluid jet, which remains collimated and coherent before it impinges the surface to be polished, is required. A method of jet stabilization has been proposed, developed and demonstrated whereby the round jet of magnetorheological fluid is magnetized by an axial magnetic field when it flows out of the nozzle. It has been experimentally shown that a magnetically stabilized round jet of MR polishing fluid generates a reproducible material removal function (polishing spot) at a distance of several tens of centimeters from the nozzle. In doing so, the interferometrically derived distribution of material removal for an axisymmetric MR Jet, which impinges normal to a plane glass surface, coincides well with the radial distribution of rate of work calculated using computational fluid dynamics (CFD) modeling. Polishing results support the assertion that the MR Jet finishing process may produce high precision surfaces on glasses and single crystals. The technology is most attractive for the finishing of complex shapes like freeform optics, steep concaves and cavities.

Magnetorheological Jet (MR JetTM) Finishing Technology

2005 ◽  
Vol 128 (1) ◽  
pp. 20-26 ◽  
Author(s):  
William I. Kordonski ◽  
Aric B. Shorey ◽  
Marc Tricard
Keyword(s):  
High Precision ◽  
Material Removal ◽  
High Speed ◽  
Axial Magnetic Field ◽  
Fundamental Property ◽  
Cfd Modeling ◽  
Surface Shear Stress ◽  
Round Jet ◽  
Mr Polishing Fluid ◽  
The Impact

Conformal (or freeform) and steep concave optics are important classes of optics that are difficult to finish using conventional techniques due to mechanical interferences and steep local slopes. One suitable way to polish these classes of optics is by using a jet of abrasive/fluid mixture. The energy required for polishing may be supplied by the radial spread of a liquid jet, which impinges a surface to be polished. Such fluid flow may generate sufficient surface shear stress to provide material removal in the regime of chemical mechanical polishing. Once translated into a polishing technique, this unique tool may resolve a challenging problem of finishing steep concave surfaces and cavities. A fundamental property of a fluid jet is that it begins to lose its coherence as the jet exits a nozzle. This is due to a combination of abruptly imposed longitudinal and lateral pressure gradients, surface tension forces, and aerodynamic disturbance. This results in instability of the flow over the impact zone and consequently polishing spot instability. To be utilized in deterministic high precision finishing of remote objects, a stable, relatively high-speed, low viscosity fluid jet, which remains collimated and coherent before it impinges the surface to be polished, is required. A method of jet stabilization has been proposed, developed, and demonstrated whereby the round jet of magnetorheological fluid is magnetized by an axial magnetic field when it flows out of the nozzle. It has been experimentally shown that a magnetically stabilized round jet of magnetorheological (MR) polishing fluid generates a reproducible material removal function (polishing spot) at a distance of several tens of centimeters from the nozzle. The interferometrically derived distribution of material removal for an axisymmetric MR Jet™ , which impinges normal to a plane glass surface, coincides well with the radial distribution of rate of work calculated using computational fluid dynamics (CFD) modeling. Polishing results support the assertion that the MR Jet finishing process may produce high precision surfaces on glass and single crystals. The technology is most attractive for the finishing of complex shapes like freeform optics, steep concaves, and cavities.

The Mechanisms of Material Removal in the Fluidized Bed Machining of Polyvinyl Chloride Substrates

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
M. Barletta ◽  
V. Tagliaferri ◽  
F. Trovalusci ◽  
F. Veniali ◽  
A. Gisario
Keyword(s):  
Fluidized Bed ◽  
Polyvinyl Chloride ◽  
Process Parameters ◽  
Material Removal ◽  
High Speed ◽  
Mesh Size ◽  
Main Process ◽  
Machining Time ◽  
Polymeric Substrates ◽  
The Impact

In this paper, the mechanisms of material removal during the fluidized bed machining (FBM) of polymeric substrates are analyzed. Cylindrical components composed of polyvinyl chloride (PVC) were exposed to the impact of abrasives while rotating at high speed within a fluidization column. The interaction between the Al2O3 abrasive media and the PVC surfaces was studied to identify the effect of the main process parameters, such as the machining time, the abrasive mesh size, and the rotational speed. The change in the surface morphology as a function of the process parameters was evaluated using field emission gun—scanning electron microscopy (FEG-SEM) and contact gauge profilometry. An improvement in the finishing of the processed surfaces was achieved, and the related mechanisms were identified. The roles of the impact speed and the contact conditions between the abrading particles and the substrate were also investigated.

scholarly journals Mathematical modeling of high-precision surfaces finishing in elastic plates with surface-active matters

2016 ◽  
Vol 1 (10) ◽  
pp. 26-32
Author(s):  
Владимир Богуцкий ◽  
Vladimir Bogutskiy ◽  
С. Братан ◽  
S. Bratan ◽  
А. Колесов ◽  
...  
Keyword(s):  
High Precision ◽  
Material Removal ◽  
Elastic Plates ◽  
Stochastic Nature ◽  
Manufacturing Operations ◽  
Current State ◽  
Operations Control ◽  
Surface Active ◽  
The Impact ◽  
A Current

At present a significant problem at the production of high-precision machinery and devices is the ensuring of stability of quality specified parameters and increase of working productivity. The simultaneous achievement of these values may be obtained only at the expense of the destination of optimum modes and methods of manufacturing operations control for that there were necessary adequate mathematical models. The existing engineering processes are formed on determined procedures without taking into account a stochastic nature of a process and the interference of chemical and mechanical phenomena in the area of working. In the paper the mechanism of allowance removal at finishing with abrasive pastes having in their composition as fillers the surface-active matters as a factor defining the effectiveness of a finishing procedure is investigated. A process mathematical model is developed allowing the computation of material removal at any time at different algorithms of modes changes including parameters of a contact area, a current state of a surface layer in a blank. A model formed taking into account the process of passivation, machine cutting, takes into account a stochastic character of a process and allows estimating differentially the impact of separate factors upon material removal.

Vibration Tests of the Processing Shaft Cascading Structure in High Speed and High Precision PCB Drilling Machine

2012 ◽  
Vol 246-247 ◽  
pp. 1263-1267
Author(s):  
Feng Gong ◽  
Yan Ping Tan ◽  
Ji Bin Li
Keyword(s):  
High Precision ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Drilling Machine ◽  
Guide Rail ◽  
Basic Part ◽  
Free Mode ◽  
Set Up ◽  
Vibration Tests ◽  
The Impact

It is necessary to study the dynamic characteristics of the structure of processing shaft cascade in high speed and high precision PCB drilling machine because of its great impact on the drilling precision. As a basic part, the dynamic characteristics of the structure of cascade depend on the dynamic characteristics of the Z-axis floor. Based on it, firstly, the free mode test is conducted on the Z-axis floor, the same as the modes that it is just set up on the guide rail, the cascade is added and the motor spindle has been added on the Z-axis floor. From the four situations, the modal pa-rameters are gained in the tests. Then the ODS test is carried out and the vibration is analyzed in the real situation. The vibration tests of the cascade comprehensively acquire dynamic characteristics from the Z-axis floor before being assembled to the Z-axis floor which is entirely cascaded on the Z axis. Acknowledge of the impact that the vibrations bring to the drilling precision of the drilling machine provides the direction of improving the structure.

CFD Modeling Effects on Unsteady Multistage Simulation for a Transonic Axial Compressor

2011 ◽  
Author(s):  
Mai Yamagami ◽  
Hidekazu Kodama ◽  
Dai Kato ◽  
Naoki Tsuchiya ◽  
Yasuo Horiguchi ◽  
...  
Keyword(s):  
Performance Prediction ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Path Model ◽  
Cfd Modeling ◽  
Geometry Modeling ◽  
The Impact

Unsteady three-dimensional multistage calculations are performed for a highly loaded, high-speed axial compressor to investigate the impact of real geometry modeling and different numerical approaches on the accuracy of the performance prediction. First, two features of the real geometries are separately compared with the calculation which consists of a pure flow path model except that rotor tip clearances are considered. One treats leakage generated by part gaps between variable stator vanes and the annulus lines. Another incorporates seal cavities to model leakage underneath the shrouded stators. Then, the influence of different numerical approach with different turbulence models is also investigated. Discussion on the impact of the CFD modeling on the performance prediction focuses on the prediction accuracies of stage operating points and spanwise mixing. It is suggested that a realistic simulation of turbulent-type flow unsteadiness in a multistage machine is important for an accurate prediction of spanwise mixing phenomena.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Enhancement of EDM Performance by Using Copper-Silver Composite Electrode

2020 ◽  
Vol 38 (9A) ◽  
pp. 1352-1358
Author(s):  
Saad K. Shather ◽  
Abbas A. Ibrahim ◽  
Zainab H. Mohsein ◽  
Omar H. Hassoon
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
High Speed ◽  
Composite Electrode ◽  
Removal Rate ◽  
Pure Copper ◽  
High Speed Steel ◽  
Pulse On Time ◽  
Pulse Off Time

Discharge Machining is a non-traditional machining technique and usually applied for hard metals and complex shapes that difficult to machining in the traditional cutting process. This process depends on different parameters that can affect the material removal rate and surface roughness. The electrode material is one of the important parameters in Electro –Discharge Machining (EDM). In this paper, the experimental work carried out by using a composite material electrode and the workpiece material from a high-speed steel plate. The cutting conditions: current (10 Amps, 12 Amps, 14 Amps), pulse on time (100 µs, 150 µs, 200 µs), pulse off time 25 µs, casting technique has been carried out to prepare the composite electrodes copper-sliver. The experimental results showed that Copper-Sliver (weight ratio70:30) gives better results than commonly electrode copper, Material Removal Rate (MRR) Copper-Sliver composite electrode reach to 0.225 gm/min higher than the pure Copper electrode. The lower value of the tool wear rate achieved with the composite electrode is 0.0001 gm/min. The surface roughness of the workpiece improved with a composite electrode compared with the pure electrode.

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