In this research, a one-way abrasive flow machining (AFM) was sketched and built, and the impact of temperature on surface roughness (Ra) values and material removal rate (MRR) before and after each ...test have been investigated considering the SiC. Al2O3, and B2O3 particles as abrasive particles. The abrasive particles were dispersed at 35 wt.% in the prepared media. The findings revealed that the media containing Al2O3 abrasive particles had higher surface roughness compared to the SiC and B2O3 particles. The maximum variation of surface roughness for SiC, Al2O3, and B2O3 particles was observed at −196 °C, which was 2.991, 2.588, and 1.684, respectively. In addition, the material removal rate values decreased for all the prepared samples as the temperature was reduced. At lower temperatures, lower material removal rate values were recorded since the viscosity of the abrasive paste increased.
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•Temperature efficacy on surface roughness and material removal rate were analyzed.•Comparison between SiC, Al2O3, and B2O3 particles as abrasive particle was investigated.•The SEM morphologies of the worn surfaces represented that abrasive particles caused finer surfaces.•Media containing Al2O3 abrasive particles had higher surface roughness.•Material removal rates decreased with the temperature decrement.
•A novel fixture for simultaneous finishing of all surfaces of ring-shaped alloy workpiece is developed.•Different machining parameters have been studied in terms of surface roughness on inner, ...outer, and side surface.•Mechanism of finishing has been explained along with statistical analysis at 95 % confidence level.•Metallurgical examination has been performed to reveal the surface endowment.
The present research investigations are based on the simultaneous finishing of ring-shaped cylindrical aluminium alloy workpiece having utility in multitude areas such as medical, defence, automobile, aerospace, and manufacturing ventures. To accomplish this objective, a novel in-situ fixture is designed and fabricated for simultaneous finishing of the inner, outer, and side surface. The silicone polymer-based abrasive media is prepared and is tested on the workpiece. The effect of different machining parameters is investigated in terms of response characteristics such as a change in surface roughness and percentage improvement. The surface roughness before and after abrasive flow machining has been analyzed under a microscope to reveal surface endowment. It has been pragmatically observed that abrasive mesh size, the concentration of abrasives, and a number of passes has a significant effect on change in surface roughness. The maximum percentage improvement in the surface roughness found to be 35.71 %, 37.89 %. and 27.16 % on the inner, outer, and side surface respectively. The surface micrographs after finishing showed the direction of abrasives, media flow direction, the direction of single point cutting tool, and material removal via ploughing effect owing to the high indentation of abrasive grits.
The components used in aerospace, automotive, and biomedical industries are made up of modern materials like titanium alloys, ceramics, composites etc. However, the complexity in the shape of such ...materials limits the use of conventional processes for their finishing. Abrasive flow machining (AFM) is one such alternative to finish these components. In this review study, a systematic methodology has been used for a data-supported review of AFM. The methodology includes a structured literature search, bibliometric analysis, and text mapping. The development of AFM variants, parametric analysis, abrasive media development, modeling of responses of AFM, and application-based studies are identified as major fields of investigations in AFM. The study of AFM variants includes the development of better versions of AFM using external assistances to improve process performance. The effect of input parameters on process responses is studied for parametric analysis. The development of abrasive media using different base polymers and their use have also been explained. The modeling of process responses of AFM is explicated using mathematical equations. Besides this, the behaviour of abrasive media has been analyzed using mathematical and simulation studies. The details about the use of AFM in finishing of biomedical components, automotive parts, gears, additively manufactured parts, turbine blades, and micro geometries have been provided to understand the practical applications of AFM in the recent past.
•Insights into AFM uniformity for SLM channels are thoroughly examined.•A CFD model considering wall slip and shear thinning behavior in AFM is proposed.•A novel material removal model for AFM is ...established and validated.•The cause of uneven material removal of SLM internal channels in AFM is revealed.
Selective laser melting (SLM) has emerged as a transformative technology for fabricating intricate parts. However, a deteriorated as-built surface remains an Achilles’ heel due to the inherent layer-wise building features, driving the demand for post-finishing processes like abrasive flow machining (AFM) for internal channel refinement. Despite AFM's potential to improve surfaces, a significant research gap exists in ensuring uniform material removal and consistent surface quality. This challenge is accentuated by the complex geometry of SLM channels and the lack of a detailed material removal model considering wall slip velocity and interaction forces. To address this challenge, this study delves deep into the post-finishing process uniformity of AFM for internal channels made by SLM. Investigating the impacts of building orientation angle, abrasive media viscosity, and internal channel geometry on finishing uniformity, the nuances of material removal, surface morphology, and roughness were explored with specially designed rectangular right-angle tubes as samples. The proposed method introduced a CFD simulation model that captures complex abrasive media behaviors, including wall slip and shear thinning. Furthermore, the innovative approach of the study is highlighted by the development of a modified Preston material removal model, which for the first time utilizes the concentrated suspensions theory to reveal the physical mechanisms underlying material removal in AFM. Our exhaustive research demonstrates that experimental outcomes harmoniously resonated with our modified Preston model's predictions, offering robust validation. This significant finding reveals a direct positive correlation between material removal and several parameters, notably particle phase normal stress but not pressure effects. Moreover, geometric variations in the flow channel significantly impact non-uniform removal in AFM, with the challenge escalating as abrasive media viscosity increases. Contrarily, the role of the building orientation angle is less pronounced. Insights into surface quality indicate that a steeper build orientation angle diminishes the initial surface quality of SLM channels. However, this disparity lessens as AFM progresses, underscoring AFM's potential to achieve uniform surfaces of high quality. Therefore, this study offers exceptional insights into AFM uniformity for SLM channels, highlighting pivotal parameters and their effects.
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Abrasive flow machining (AFM) process, as a widely known technique for finishing internal surfaces of complex parts, can significantly improve the performance and reliability of components in ...numerous industries. Prediction of material removal rate (MRR) is a vital task in AFM process because it significantly affects the efficiency and cost-effectiveness of the process. In-depth studies about the influence of input parameters on material removal in AFM process, however, are limited. In this paper, the mechanism of material removal was investigated, and a MRR modelling was then established in which viscoelastic extrusion modelling with wall slip conditions was employed in AFM process. A novel fixture with gradient shear flow channel was designed. MRR obtained by simulations and experiment showed a reasonable agreement. Finally, parameters, including abrasive media pressure, velocity and shape geometry of flow channel, were identified as key factors affecting MRR in AFM process. Established computational fluid dynamics (CFD) analysis and MRR modelling can be a powerful tool to determine MRR in future AFM process.
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•Viscoelastic MRR modelling was established based on mechanism of indentation and wall slip interactions.•Novel designed fixture formed various values of media pressure, velocity and shear rate in one single extrusion.•Experiments and simulation saw well a agreement in abrasive media extrusion profiles with an error of below 10 %.•Predicted MRR model and experiments both proved the most influential factor was pressure, followed by velocity and shear rate.
A new precision finishing process for complex internal geometries using smart magnetorheological polishing fluid is developed. Magnetorheological abrasive flow finishing (MRAFF) process provides ...better control over rheological properties of abrasive laden magnetorheological finishing medium. Magnetorheological (MR) polishing fluid comprises of carbonyl iron powder and silicon carbide abrasives dispersed in the viscoplastic base of grease and mineral oil; it exhibits change in rheological behaviour in presence of external magnetic field. This smart behaviour of MR-polishing fluid is utilized to precisely control the finishing forces, hence final surface finish. A hydraulically powered experimental setup is designed to study the process characteristics and performance. The setup consists of two MR-polishing fluid cylinders, two hydraulic actuators, electromagnet, fixture and supporting frame. Experiments were conducted on stainless steel workpieces at different magnetic field strength to observe its effect on final surface finish. No measurable change in surface roughness is observed after finishing at zero magnetic field. However, for the same number of cycles the roughness reduces gradually with the increase of magnetic field. This validates the role of rheological behaviour of magnetorheological polishing fluid in performing finishing action.
Additively manufactured metallic parts compete with casted and forged parts in physical and mechanical properties. However, the presence of various surface defects, such as balling and staircase ...effects, lack of fusion, surface undulations, etc., hinders the direct functional application of the as-built part and demands further post-processing. Abrasive flow finishing (AFF) is an extensively employed post-processing technique to finish additively manufactured parts. This process uses polymer rheological abrasive medium (abrasive medium) to finish internal and external surfaces. Even though significant research has been carried out on the surface finishing of selective laser melted metallic parts, the mechanism of material removal and surface finish improvement is not explored much. In the present work, the mechanism of deballing and surface finish improvement on selective laser melted 18Ni300 steel using the AFF process is studied. A newly developed polysaccharide-based abrasive media with monomodal and bimodal abrasive particle distribution are employed for finishing. At an extrusion pressure of 7.5 MPa, the influence of abrasive particle distribution and the number of finishing cycles on the amount of material removed and percentage change in surface roughness (% ΔRa) is observed. It was found that the abrasive medium with bimodal abrasive particle distribution resulted in more material removal and % ΔRa than monomodal. Surface roughness reduction of up to 93% was obtained using the abrasive medium with bimodal abrasive particle distribution. It was noticed that the loosely adhered powder particles were removed within the initial 15 cycles, and the balling effect was completely eliminated within 75 cycles. After 375 cycles, the as-built side surface was free from all other surface defects, such as micro-cracks, shallow pits, material ridges etc. Based on the obtained results, a suitable material removal mechanism in selective laser melting parts using the AFF process was proposed.
•Developed a polysaccharide-based polymer rheological abrasive medium for finishing.•Abrasive particle distribution in abrasive medium has a significant effect on % ΔRa.•Adhered powder particles responsible for 45–65% of initial surface roughness.•Particle distribution in the abrasive medium could affect critical surface roughness.•Material removal mechanism in abrasive flow finishing of SLM part was proposed.
•Novelly developed shear-thickening guar gum hydrogel based media for AFM is proposed in this paper.•A new model for the calculation of shear rate under shear-thickening condition is established and ...validated.•Surface roughness in terms of Ra using this media reduces from 120.12 nm to 6.48 nm, with a mirror surface obtained.•The conclusions show that shear thickening in AFM is an efficient way to develop the polishing efficiency and quality.
Abrasive flow machining (AFM) is a non-traditional finishing method by extruding abrasive media through workpieces’ surfaces. In AFM process, the machining capacity of traditional shear-thinning media will be reduced with the decline of viscosity at high shear rate condition. Additionally, the environmental-friendly property of traditional oil-soluble media is poor as the recycling of the media is difficult. In this paper, with an attempt to apply shear thickening to AFM, a novel type of guar gum hydrogel based media with shear-thickening property is proposed. To investigate its shear-thickening and finishing performance, a model of identifying the shear-thickening behavior in AFM is established. Results of the validation experiment show that the model can identify and predict the experimental conditions accurately, and the simulation results are approximately some with the model results. Results of AFM experiments show that finely polished surface can be obtained in the AFM process utilizing this new media. Compared with styrene-butadiene rubber based media (traditional shear-thinning media for AFM), guar gum hydrogel based media can obtain a better finished surface under shear-thickening condition. With shear rate increasing from shear-thinning phase to shear-thickening phase, material removal rate for AISI316 stainless steel in the experiment utilizing this new media increases from 69 mg/h to 351 mg/h, and surface roughness in terms of Ra under shear-thickening condition reduces from 120.12 nm to 6.48 nm.
Abrasive flow machining (AFM) is a non-traditional surface finishing method by extruding abrasive media through workpieces' surfaces. It is difficult to implement uniformity and controllability for ...material removal in AFM, which makes predictions of material removal and its distribution along media flow direction significantly imperative. In this paper, a new predictive model for material removal in AFM is proposed based-on combination of material removal model for single abrasive and statistics model of active abrasives. To validate its applicability, two experiments are conducted to calibrate the material removal model, and another two experiments are carried out to validate the calibrated material removal model. Results show that this model can predict material removal in terms of profile height variation ΔH and variation trend of mass variation ΔM precisely, with predictive error (δerror) of 6.4% and 6.9% achieved in the validation experiments. In the case that the workpiece and flow channel are given, the variation of profile height ΔH on the workpiece surface shows consistent distribution trend with the distribution of the pressure and media flow velocity on the workpiece surface.
•A material removal model is proposed to predict distribution of material removal along flow direction in AFM process.•A repositioning method is proposed to gauge material removal by measuring profiles before and after AFM process.•Predictions of material removal distribution in terms of profile height variation ΔH are justified by validation experiments.•Relationship between distribution of material removal and pressure field of abrasive media flow is established.
•Abrasive flow machining (AFM) has been applied on SLM produced channels.•Investigation of the influence of AFM on the surface roughness and on the residual stress state of channels.•An original ...testing method to characterise the fatigue resistance of internal channels.•AFM is able to improve significantly the fatigue strength of channels.
Conformal cooling channel technology is becoming a common practice in the design of injection moulds made of maraging steel thanks to additive processes such as selective laser melting (SLM). However, the rough surface created by SLM can have an adverse effect on the fatigue life of the mould because of the rough channel surfaces that induce stress concentrations in the valleys of the roughness. So as to overcome this problem, abrasive flow machining (AFM) has been applied on SLM produced channels. This paper investigates the influence of this superfinishing technique on the surface roughness and on the residual stress state of channels. It is shown that AFM is capable of improving the surface roughness and inducing compressive residual stresses. Then, this work proposes an original testing method to characterise the fatigue resistance of internal channels, that reveal that AFM is able to improve significantly the fatigue strength of channels and to recover the fatigue strength commonly obtained with electrical discharge machining (EDM).
