Air-jet Machine Research Articles

Evaluation of the machinability and enhancement of biological response of ZTA-based 13-93 bio-glass composite materials

Besides the exceptional mechanical and biocompatible properties, zirconia toughened alumina (ZTA) has limited biomedical applications due to its bio-inertness properties. The present work examines the effect of 13-93 bio-glass (BG) addition on the machinability and biological responses of ZTA-containing BG composites. The ZTA–xBG (x = 0, 5, 10, 15, and 25 wt%) composites have been synthesized and sintered at 1250°C for 4 h. The machining of composite samples is done on an abrasive air-jet machine (AAJM), and their machinability is studied in terms of surface roughness (SR), material removal rate (MRR), and mechanics of material removal (MMR). The result indicates that MRR decreases and SR enhances with the addition of BG. The MMR is studied using machined surface morphology, and the results confirm that material removal is due to the large erosion crater. The relative density is decreased with enhancing the BG content except for a sample containing a high amount of BG (25 wt%). Mechanical properties such as hardness and flexural strength are enhanced by BG content up to 25 wt%. In-vitro analysis in simulated body fluid (SBF) reveals that both corrosion and bioactivity increase as BG concentrations increase. According to the in-vitro cell culture data, adding BG to ZTA improves cellular viability with BG content up to 25 wt%. The antibacterial result shows that the viability of the bacterial cells on the composites has significantly decreased with BG content. As a result, biomaterials with this architecture may be used as bone implants.

Influence of bioactive glass addition on the machinability, mechanical and biological response of Mg-PSZ-based biocomposites

The incorporation of bioactive glass (BG) into zirconia-based composite materials shows a feasible option to enhance the biological properties, reduce the sintering temperature, and resist the transformation of the tetragonal phase of zirconia. In this present work, the bioceramic composites, having the general formula [(100-x) (8 Mg-PSZ) – x (13–93 BG)] where x = 0 to 25 wt%, have been prepared and evaluated the effect of BG amounts on the machinability, mechanical and biological behavior of the composite material. The machining experiment is performed on an abrasive air jet machine (AAJM), and machinability is evaluated in the form of material removal rate (MRR), surface roughness (SR), and mechanics of material erosion (MME) at room temperature. The machinability results show that MRR decreases with enhancing the BG contents, and the SR follows the opposite trend of MRR. The MME indicates that the material is removed from the surface mainly due to the erosion crater and brittle fracture. Further, mechanical properties are evaluated, and it is found that the inclusion of BG frits and sintering temperature is substantially associated with the relative densities and the mechanical characteristics. Adding BG reinforcements increases the mechanical characteristics at lower sintering temperatures (1250 °C) while reducing the mechanical characteristics except hardness at higher sintering temperatures (1350 °C). Elastic modulus decreases with the addition of BG content up to 15 wt%; after that, it slightly increases up to 25 wt%. The in-vitro bioactivity and bio-degradation are tested in simulated body fluid (SBF), and both are increased by enhancing the BG contents up to 25 wt%. The in-vitro cell culture is performed on the MG-63 cell line. The biocompatibility increases with BG concentration (up to 25 wt%). Based on experimental results, it may be concluded that 8 Mg-PSZ/13-93BG bioceramic composites may be a potential choice for biomedical applications.

Response Optimization of Machining Parameters using MCDA-Vikor Method for Acrylic Glass with AHAJM

Abstract: Abrasive Hot Air Jet Machining (AHJM) is becoming one of the most prominent machining techniques forPolymethyl Methacrylate (PMMA) and other brittle materials. In this attempt has been made to combine abrasive and hot air to form an abrasive hot air jet. Abrasive hot air jet machining can be connected to different tasks, for example, boring, surface scratching, scoring and small scale completing on the glass and its composites. The impact of air temperature onthe material expulsion rate connected to the procedure of glass carving and scoring is talked about in this article. The unpleasantness of the machined surface is additionally investigated. It is discovered that the material removal rate (MRR) increments as the temperature of transporter media (air) is expanded. In the present work to be attempt to investigate machining characteristics of PMMA material on hot air abrasive jet machining. In hot air abrasive jet machining(HAJM) abrasive particles stay on abrasive particle stay molten by compacted air in a closed chamber and are intensive over the objective surface over a nozzle the stream of particles coming out of the nozzle through very high velocity’s (175-300m/s) impacts the objective surface and eliminates the material by destruction. The investigation has to be carried on to study the effect of process parameters as material removal rate(MRR) as surface roughness(SR) with different input parameters like Air Pressure, , Size Of Abrasives , Stand-Off Distance ,Temperature Of Carrier Gas. In this experimental process Tungstencarbide coated nozzles were to be used flow of silicon carbide(sic) particles will be used.The Poly(methyl methacrylate) (PMMA), furthermore saw as acrylic glass, acrylic material, or plexiglass as suitably as by using the change names Plexiglas, Crylux, Lucite, Acrylate. PMMA it is an unquestionable thermoplastic .the creation formula of PMMA is (C5O2H8)n it has incredible properties to, for instance, lightweight, 92% Transparent observable light effect inside 3mm of thick material, extraordinary solidarity to consider another polystyrene. it's for the most part important in these zones, for instance, Because of its direct properties, lightweight and preferable quality took a gander at over glass, It was broadly usedto make aircraft windshields, shades and weapon turrets. After this couple of different business applications were made for PMMA, for instance, glass material, façade arrangement, publicizing, vehicle headlamps, etc.,

A new elastic abrasive jet machining method for post–treatment of tool coatings: A case study on TiAlN coated tools for titanium machining

This paper investigates the effect of post–treatment by a newly–developed elastic abrasive jet machining (EAJM) method on the TiAlN coated tools. It employs the self–developed multi–element polymer beads as abrasives in air jet machining. The results indicate that post–treatment with EAJM can prominently improve the coating properties. Additionally, the wear resistance is improved as the tool wear is reduced up to 19%. While the wear resistance can be improved with increasing EAJM parameters, it can be diminished if the EAJM parameters exceed a proper range. Statistical analysis shows that the effect of EAJM on tool performance depends on the product of jetting time and pressure. The proper selection should range from 0.56 × 104 kPa·s to 2.96 × 104 kPa·s.

Numerical and experimental investigations on the effect of particle properties on the erosion behavior of aluminum alloy during abrasive air jet machining process

Numerical and experimental investigations on the effect of particle properties on the erosion behavior of aluminum alloy during abrasive air jet machining process

Reduction of Friction Using Microabrasive Air Jet Machining

In this paper, we introduce a microabrasive air jet (micro-AAJ) machining system and describe machining results obtained while using it. Our research activities have focused on the development of micro-AAJ machining methods for friction reduction without requiring a mask. Through this study, we want to show that such processing is possible without a mask when using the AAJ method. In this paper, a micro-AAJ machining system is introduced, and the processing results are described. By comparing the friction coefficient of texturing under various conditions, the relative relationship between the surface shape and the friction coefficient can be identified. We investigated the effect of the relationship between rotating velocity, traverse speed, density of the patterned area and injection pressure on friction. The friction is decreased with a low traverse speed and high-density patterned area under high-speed driving conditions, as verified by experiments using a friction test system.

Experimental study on the influence mechanism of micro-abrasive air jet machining on the surface quality of Ti-6Al-4V titanium alloy formed by selective laser melting

This experiment studied the effect and mechanism of micro-abrasive air jet machining (AAJ) on the surface quality of SLM-formed TC4 titanium alloy specimens under different air pressures and jet angles. The results showed that the width of the AAJ processing area increased with the increase of air pressure but decreased with the increase of the injection angle. The surface quality of SLM samples could be improved effectively by AAJ processing. The optimized percentage of surface roughness value (Sa) was the largest, reaching 54% when the injection angle was 60ᵒ and the air pressure was 0.5 MPa; The surface hardness of the sample increased the maximum percentage, reaching 22% when the injection angle was 75ᵒ, and the air pressure was 0.5 MPa. The initial abrasive grains mainly had three shapes: flake, block, and column. The flaky abrasive grains had sharp edges, a good effect on matrix removal, large processing area but shallow depth of action; The block abrasive particles were mainly removed by extrusion and accompanied by severe friction with the substrate, and layered chips were generated; The columnar abrasive grains mainly scratched the surface of the substrate to generate scratches. The material's erosion rate (ER) was the largest, reaching 1.3%, and the processing efficiency was the highest when the injection angle was 60ᵒ and the air pressure was 0.4 MPa. The α′ martensite near the sample’s surface was elongated by AAJ processing, and the direction was parallel to the sample's surface. The depth of processing influence was the largest, reaching about 30 μm when the injection angle was 75ᵒ and the air pressure was 0.5 MPa.

Effect of process parameters on Mg/Gr (MMC) and GFRP by using abrasive air jet machine

Conventional methods are difficult to use for machining hard materials. The non-conventional techniques like Abrasive Air Jet Machine (AAJM) are suitable for machining hard materials. The main objective is to evaluate and optimize the machining parameters of Magnesium alloy (AZ91D) / Graphene (MMC) and Glass fiber reinforced polymer (GFRP) using Abrasive air jet machine. In this study, we examined the influence of multiple process parameters on the predominant machining criteria for metal removal rate (MRR), including air pressure, stand-off distance and time. Sic particles were used as an abrasive particle during machining process. In addition to analyzing and optimizing the machining parameters of an abrasive jet machine, Taguchi's L9 is used to determine the Material Removal Rate (MRR) and the kerf taper angle (θ) during the machining process. Based on the experimental results, the machining parameters like pressure and stand of distance influenced the material removal rate.

Improvement of process repeatability and resolution in abrasive air jet machining via viscous slurry entrainment

The unsteady powder mass flowrate of the available feeding systems and the bad control of the areas being eroded have been often noticed in the abrasive air jet machining process. In addition to the delivery of dry powder, the powder can be evenly mixed with liquid to form a slurry, and then sent to the mixing chamber of an air jet machine; i.e., multiphase jet machining (MJM) was proposed in this paper. The method whereby using the viscous water to suspend the abrasives was found to enhance the stability of powder mass flowrate, thereby decreasing the fluctuation in the machining depth. Whereafter, five types of liquid-based slurries were prepared and their effects on the jet erosion zone were investigated. It was found that the control of the erosion zone was improved to varying degrees when the abrasives were transported into the air jet by viscous liquid as the carrier fluid due to the two roles: reducing the occurrence of third and/or second particle impacts; inducing a viscous boundary layer that could reduce the negative effect of the divergence of jet beam and particle rebounding. In particular, the use of an oil-based slurry could completely eliminate the unwanted frosted zone around the machined features. CFD simulations were used to understand the mechanisms causing these effects. Overall, it is shown that the abrasive air jets can be designed to have a good resolution, so it is feasible to mill or polish surface without the need for a mask to define the edges.

Characteristics of cryogenic abrasive air-jet direct-write machining: A comparison with abrasive air-jet direct-write machining at oblique angles

• The velocity model of abrasive particles in the radial direction is modified. • Abrasive air-jet (AAJ) direct-writing of PDMS at 15° is presented. • Cryogenic abrasive air-jet (CAAJ) direct-writing of PDMS is presented. • CFD models of AAJ and CAAJ direct-writing are established. • "U"-shaped micro-channels are obtained by CAAJ and compared against AAJ at 15°. Cryogenic abrasive air-jet (CAAJ) machining technology is performed simultaneously with the occurrence of the glass transition for PDMS material. However, the mask material is also cooled with cryogenic PDMS cooling. Then, they both show significant brittle characteristics. Therefore, this leads to very poor selectivity between the mask and the PDMS. To solve this problem, CAAJ direct-write machining under unmasking conditions are proposed based on the modified velocity model of abrasive particles in the radial direction. This technique was used to direct-write machined the PDMS materials under small SOD. Then, the effect of cryogenic conditions on machining characteristics of PDMS micro-channels was studied by comparing the abrasive air-jet direct-write machining at oblique angles and CAAJ direct-write machining technologies through a series of experimental studies and CFD simulations. The results show that the material removal mode is transformed to a semi-brittle one, which greatly improves erosion removal efficiency, aspect ratio and bottom surface roughness of the micro-channel. On the other hand, the change in the viscosity of the jet medium has a crucial influence on the geometry of the micro-channel. The rebound direction of abrasive particles changes, and the sidewall of micro-channels is secondarily eroded due to an increase in jet medium viscosity in CAAJ. This, in turn, leads to a micro-channel with "U"-shaped profile. In addition, during CAAJ direct-write machining, sliding, scratching, and rolling of abrasive particles caused by bubble bursting can effectively reduce the bottom surface roughness of the micro-channel.

Effect of nozzle pressure ratios on the flow and distribution of abrasive particles in abrasive air jet machining

Effect of nozzle pressure ratio (NPR) on the flow and distribution of abrasive particles was investigated to improve supersonic abrasive air jet machining (AAJM) effect. The supersonic air-particle flow was simulated via CFD-DEM modeling, which was verified by AAJM experiments. It was concluded that NPR determined the acceleration and distribution of particle flow by controlling the structure and turbulent kinetic energy of the air jet free-flow field. When NPR = 1.12, the particle flow field had a longer stable region and a higher particle velocity, and the radial distribution resembled an n-shape. Further, in AAJM experiments, when the material was fixed in the stable region of particle flow field, the impact stresses were relatively high and uniformly distributed. Thus, when NPR = 1.12, the target material is fixed in the stable region of the abrasive particle flow, and the target material can obtain a better machining effect in the AAJM.

Optimization of process parameters on machining of graphene reinforced with magnesium based composite using abrasive jet machine

The abrasive air machine has been used widely to machine the hard materials and making the complex shapes. The main objective of this work is to evaluate and optimize the machining parameters of the Abrasive air jet machine. The machining parameters are air pressure, abrasive flow rate, and stand off distance. The Silicon carbide particles were used as an abrasive particle. The Taguchi’s L27 used to analyze and optimize the machining parameters of the abrasive jet machine, and used to determine Material Removal Rate (MRR) and kerf taper angle (θ) during the machining process. The experimental results revealed that the material removal rate was influenced by the machining parameters. The machining surfaces were evaluated by the scanning electron microscope.

Experimental investigations of machining characteristics on polydimethylsiloxane (PDMS) by cryogenic abrasive air-jet machining

Experimental investigations of machining characteristics on polydimethylsiloxane (PDMS) by cryogenic abrasive air-jet machining

A theoretical and experimental investigation of particle embedding and erosion behaviour of PDMS in micro-abrasive air-jet machining

Embedding of abrasive particles can be an unwanted consequence of micro-abrasive air-jet machining (MAJM) of polydimethylsiloxane (PMDS). In this work, the extent to which the abrasive is embedded is analyzed quantitatively by a modeling analysis involving the impact velocity, impact force, and erosion depth of the single abrasive particle on PDMS combined with the change in the material erosion removal rate. In addition, the surface morphology of PDMS was characterized under different erosion processing. The results show that the wear mechanisms is characterized by a transition from microcutting to indentation and surface fatigue, with increasing impact angle. In general, small impact angle and high air pressures are recommended to avoid embedding of abrasive particles, and the appearance of metamorphic layer. The theoretical analysis and experimental results provide potential benefits in predicting the erosion depth of the single abrasive particle and controlling the embedding of abrasive particles during machining of PDMS.

Effect of Harnesses Crossing Angle and Shed Size on Yarn Stops during Weaving on an Air Jet Machine.(Dept.T)

Effect of Harnesses Crossing Angle and Shed Size on Yarn Stops during Weaving on an Air Jet Machine.(Dept.T)

PDMS material embrittlement and its effect on machinability characteristics by cryogenic abrasive air-jet machining

Abstract The use of cryogenic abrasive jet machining (CAJM) technology for polydimethylsiloxane (PDMS) materials is increasing rapidly due to its high material removal rate and high surface quality. However, how the material properties of PDMS affect the machining properties under cryogenic conditions is still an unsolved problem. Firstly, the thermodynamic and mechanical properties of PDMS materials are studied by dynamic thermo-mechanical analysis and universal material testing. The results show that the PDMS material’s embrittlement temperature is 126 K. Secondly, evaluation of cooling temperature of PDMS during CAJM shows that the machined area has reached embrittled state. Thirdly, the effect of PDMS material’s embrittlement on the machining behaviour is studied. The experimental results show that the PDMS material exhibit increased abrasive erosion at medium-angle under cryogenic conditions and shows a semi-brittle wear mechanism. Furthermore, the erode surface’s roughness is evaluated. The result shows that the roughness decreases with decreasing air pressure at the same impact angle; with increasing impact angle, the roughness shows a trend of increase initially and then decreases. This work shows that the PDMS material’s embrittlement and the erosion response behaviour during CAJM are due to the combined effects of thermo-mechanical properties and material removal mechanisms, providing a better understanding of CAJM technology.

Thermo-physiological comfort of half bleached woven fabrics made from different cotton yarns parameters

ABSTRACT Thermo-physiological comfort of apparel clothing must be suitable for the wearer both in winter and summer seasons. Poor thermo-physiological properties can lead to discomfort, fluctuation in body temperature, poor sweat management during wear and can affect human health as well as work efficiency. For this reason, optimum thermo-physiological comfort of clothing is a prerequisite by users for any given weather. The aim of this study was to investigate the effect of cotton yarn parameters on the thermo-physiological comfort of woven fabrics. Four types of woven fabrics were developed from cotton yarn with different counts, twist, coefficient of variation of mass (CVm), neps, hairiness, thin places, thick places, strength, and elongation. Yarn samples were produced separately by carding and rotor span before they were woven on an air jet machine with the same settings. Finally, the woven fabrics were finished in a combined finishing treatment process. Thermo-physiological properties of fabrics were measured and analyzed. Statistically analyzed results showed that thermal resistance, thermal conductivity, thermal absorptivity, and air permeability of fabrics had statistically significant change with P values of 0.029, 0.035, 0.005, and 0.000, respectively. Model equations were developed based on the results to predict the comfort of the fabric.

The influence of yarn parameters on thermo-physiological comfort of cotton woven fabrics

As the global temperature increases over time due to different environmental pollutions, apparel clothing with excellent thermo-physiological comfort needs to be developed to improve human health and comfort. Thermo-physiological comfort of apparel clothing must be suitable for the wearer both in winter and summer seasons. Poor thermo-physiological properties can lead to discomfort, fluctuation in body temperature, poor sweat management during wear and can affect human health as well as work efficiency. For this reason, optimum thermo-physiological comfort of clothing is a prerequisite for users at any given weather. The aim of this study was to investigate the effect of cotton yarn parameters on thermo-physiological comfort of woven fabrics. Four types of woven fabrics were developed from cotton yarn with different counts, twist, coefficient of variation of mass (CVm), neps, hairiness, thin places, thick places, strength and elongation. Yarn samples were produced separately by carding and rotor spun before they were woven on an air jet machine with same settings. Finally, the woven fabrics were finished in a combined finishing treatment process. Thermal resistance, thermal conductivity, thermal absorptivity, thermal diffusivity, air permeability and relative water vapor permeability of the woven fabrics were measured and analyzed. Statistically analyzed results showed that thermal resistance, thermal conductivity, thermal absorptivity and air permeability of fabrics had statistically significant change with P-values of .029, .035, .005 and .000, respectively. However, from the results, the yarn parameters did not affect thermal diffusivity and water vapor permeability of fabrics. Model equations were developed based on the results to predict the comfort of the fabric from the yarn parameters.

Semi-resolved CFD-DEM modeling of gas-particle two-phase flow in the micro-abrasive air jet machining

Abrasive air jet (AAJ) machining is attractive for micromachining hard and brittle materials, while it is usually a big challenge to numerically investigate the particle velocity and concentration distribution in the particle erosion process in the AAJ. In this work, a recently developed semi-resolved CFD-DEM approach which bridges the simulation gap between the resolved and unresolved CFD-DEM, is further improved to reconstruct the background information with a double cosine kernel function. The semi-resolved CFD-DEM is then employed to numerically investigate the gas-particle two-phase flow in the AAJ and numerical results show that this semi-resolved CFD-DEM is more accurate in modeling particulate flow in the fine AAJ nozzle than the conventional unresolved CFD-DEM. We further conduct mechanism investigations on the AAJ micromachining process including particle flow characteristics inside the cylindrical nozzle, velocity, and concentration distribution over the nozzle exit, which are essential jet characteristic features. We identified the particle flow patterns, analyzed the particle distribution, and its correlation with air pressure, abrasive mass flow rate, and turbulence effects. The present simulation results and analyses can be great helpful in understanding the erosion mechanism and optimizing the setting parameters to improve the cutting performance of AAJ.

Sensitivity analysis of abrasive air-jet machining parameters on machinability of carbon and glass fiber reinforced hybrid composites

Carbon and glass fiber reinforced epoxy polymer hybrid composites facilitate to tailor the mechanical properties of the composites. However, the machining of hybrid fiber reinforced polymer composite is a challenge by conventional processes due to the different types of fiber reinforcements and anisotropic nature of composites. Researchers and scientists have evaluated the machinability of plain or single fiber reinforced polymer composites through abrasive water jet machining and abrasive air jet machining. Therefore, the present investigation emphasizes on the development of symmetrical hybrid composites, evaluation of mechanical properties and machining of the hybrid composites through abrasive air jet machining (AAJM). There are three types of hybrid composites such as C2G3]S, [CG3C]S and [CG2CG]S along with plain glass ([G]10) and carbon ([C]10) fiber reinforced polymer composites fabricated by hand lay-up technique. It is observed that the [CG2CG]S type hybrid composite has the optimum tensile and flexural strength as compared to other composites. Hence, [CG2CG]S type hybrid composites along with plain glass and carbon fiber reinforced polymer composites was considered for the machinability study. The sensitivity of AAJM process parameters on material removal rate (MRR), depth of cut (DOC) and surface roughness (Ra) are investigated and optimized through response surface methodology (RSM). The optimum machining process output predicted by the RSM model for [CG2CG]S type hybrid composite is MRR = 3.26 × 10−3 g/sec, DOC = 1.48 mm and surface roughness (Ra) = 1.48 μm. The predicted model results compared with the experimental values and found a good agreement between them. The surface morphology of the drilled composite sample is investigated under scanning electron microscope. It is observed that the surface damage of the drilled surface of the composites is minimal. Thus, the abrasive air jet machining process can be employed for drilling of polymer matrix composites to overcome the conventional machining issues.