A novel approach of jet polishing for interior surface of small-grooved components using three developed setups

It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanwhile keeping the structure intact.To overcome this challenge,small-grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer.A novel approach to multi-phase jet(MPJ)polishing is proposed,utilizing a self-developed polisher that incorporates solid,liquid,and gas phases.In contrast,abrasive air jet(AAJ)polishing is recommended,employing a customized polisher that combines solid and gas phases.After jet polishing,surface roughness(Sa)on the interior surface of grooves decreases from pristine 8.596μm to 0.701μm and 0.336μm via AAJ polishing and MPJ polishing,respectively,and Sa reduces 92%and 96%,correspondingly.Furthermore,a formula defining the relationship between linear energy density and unit defect volume has been developed.The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 J mm^(-1)to 0.22 J mm^(-1).The unit area defect volume achieved via the optimized parameters decreases to 1/12 of that achieved via non-optimized ones.Computational fluid dynamics simulation results reveal that material is removed by shear stress,and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove,resulting in uniform material removal.This is in good agreement with the experimental results.The novel proposed setups,approach,and findings provide new insights into manufacturing complex-structured components,polishing the small-grooved structure,and keeping it unbroken.

Modeling and analysis for material removal and surface roughness in fluid jet polishing of optical glass

luid jet polishing(FJP)is a non-contact polishing technology that can fabricate free-form optical surfaces with sub-micron-level form accuracy and nano-level surface roughness,especially for hard and brittle materials.The surface generation model of FJP can be used to guide the determination and optimization of process parameters and is of great significance for understanding the evolution mechanism of surface microtopography.However,predictive models for the microscopic topography of polished surfaces are still lacking.This study established a macroscopic surface profile model for predicting 3D material removal characteristics and surface texture by combining the 3D computer fluid dynamics(CFD)simulation model and single-particle erosion mechanism.A fractal theory-based erosion model has been built to calculate the material removal caused by the erosion of a single abrasive particle on the rough surface;thus,it predicts the micro-topography and surface roughness of the polished samples.A series of polishing experiments were conducted to analyze the feasibility and accuracy of the model quantitatively and study the influence mechanism of process parameters on the material removal characteristics and surface quality.Results indicated that the models could well predict material removal and surface roughness.The prediction accuracy of the surface roughness Ra and maximum removal depth is better than 91.6%and 90%,respectively.It is also found that the material removal rate of FJP could reach 0.517 mm3/min,and the surface roughness convergence rate could reach 62.9%.

Mode transition from adsorption removal to bombardment removal induced by nanoparticle-surface collisions in fluid jet polishing

The effects of impacting particles from a jet of liquid on the removal of a surface material(on the impacted workpiece)were investigated.Experimental observations show that the cross section of the material removed changed fromʹWʹ‐shaped toʹUʹ‐shaped as the size of abrasive particles was increased.Comparisons between removed material profiles and particle collision distributions indicate that the particle-surface collisions are the main reason for the material removal.The deduced number of atoms removed by a single collision implies that a transition occurs in the removal mode.For nanoscale particles,the polished surface is likely to be removed in an atom‐by‐atom manner,possibly due to the chemisorption of the impacting particles on the impacted surface.Contrarily,for the case of microscale particles,bulk material removal produced by particle bombardment is more likely to occur.The present mechanism of material removal for particle-surface collisions is further corroborated experimentally.

An Investigation of Effect of Stand-Off Distance on the Material Removal Characteristics and Surface Generation in Fluid Jet Polishing

Fluid jet polishing(FJP)is a versatile polishing process that has many advantages compared to other polishing processes.Stand-off distance(SOD)is one of the key parameters in flu id jet polishi ng.However,relatively little research work has been carried out to investigate its effect of SOD on material removal characteristics and surface generation in FJP.In this paper,a systematic investigation of the effect of SOD on the tool influence function and surface topography in FJP was conducted.Experiments were designed for FJP two kinds of materials corresponding to ductile and brittle materials.They are nickel copper(NiCu)alloy and BK7 optical glass,respectively.In this study,the SOD was varied from 2 to 35 mm.Analysis and discussions were made on its effect on the shape of TIF,material removal rate,and surface topography.It is interesting to note that the TIF shape becomes a Gaussian-like shape with large SOD both on NiCu and BK7,which provides a novel way to optimize the TIF in FJP.The variation of the material removal rate and surface roughness versus SOD on NiCu and BK7 were also determined from the experimental results.Moreover,the surface topography of NiCu and BK7 were characterized from the results measured from the white light interferometer and scan electron microscope.The outcome of the study provides a better understanding of the material removal characteristics and surface generation mechanism in FJP.

Experimental Study of Material Removal Process of Fused Silica Glass Using MR Jet Polishing System

Recently,there has been an investigation of polishing processes that has considered new ultra-precision polishing technology for micro parts and optical parts such as those with aspheric and complex shapes.One suitable means of polishing complex shapes is to use a jet of abrasive fluid.However,aerodynamic disturbances and radial spreading are generated by the unstable polishing process of the jet on the surface of the workpiece when it is being polished.A method of jet stabilization has been proposed in which the original nozzle form of a jet of magnetorheological(MR)fluid contains abrasive particles that are magnetized using a magnetic.This paper details the design of an MR jet polishing system that uses an electromagnet,a nozzle,and a hydraulic unit to stabilize a slurry jet based on MR fluid, Second,for silica glass,the polishing spot and section profile are analyzed and the effect of the MR fluid jet polishing process is evaluated.The results of the experiment show that the removal profile is W-shaped and that,in this case,a stable can be proof of a distance of several tens of millimeters from the nozzle.Such results show the possibility of applying the proposed polishing method using MR fluids in ultra-precision micro and optical parts production processes. MR jet polishing shows great potential for use as a new type of precision surface polishing technology.In particular,this is a highly valuable process for the polishing of complex shapes such as micro parts,concaves parts,and cavities.

Defect-free surface of quartz glass polished in elastic mode by chemical impact reaction

Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.