Surface enhancement of FDM patterns to be used in rapid investment casting for making medical implants

2019 ◽  
Vol 25 (5) ◽  
pp. 904-914 ◽  
Author(s):  
Vivek Kumar Tiwary ◽  
Arunkumar P. ◽  
Anand S. Deshpande ◽  
Nikhil Rangaswamy
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Surface Finish ◽  
Investment Casting ◽  
Chemical Treatment ◽  
Medical Implants ◽  
Post Processing ◽  
Content Type ◽  
Casting Technique ◽  
Processing Treatment

Purpose Due to intrinsic limitations, fused deposition modelling (FDM) products suffer from the bad surface finish and inaccurate dimensional accuracies restricting its usage in many applications. Hence, there is a need for processing polymer patterns before, during and after their productions. This paper aims to highlight the importance of pre- and post-processing treatments on the FDM-based acrylonitrile butadiene styrene patterns improving its surface quality so, that it can be used in rapid investment casting process for making medical implants and other high precision components. Design/methodology/approach As a part of pre-processing treatment, the machine parameters affecting the surface quality were identified and optimised using design of experiments. The patterns developed after the first stage of optimisation were given different post-processing treatments, which included vapour smoothening, chemical treatment and sand paper polishing. The results were compared and the best ones were used for making patterns for making medical implants via rapid investment casting technique. The surface quality was checked while the dimensional changes happening during the stages of this hybrid technique were recorded using a three-dimensional optical scanner. Findings The surface roughness of the FDM based ABS patterns reduced from 21.63 to 14.40 µm with pre-processing treatments. Chemical treatment (post-processing treatment) turned to be the most suitable technique for reducing the surface roughness further down to 0.30 µm. Medical implants that used these pre- and post-processing treatments gave an average surface roughness of 0.68 µm. Cost and lead time comparisons showed that rapid investment casting technique can be a better method for low volume, customised and with specific requirements. Originality/value FDM parts/medical implants produced by rapid investment casting technique suffer from the inferior surface finish and inaccurate dimensional accuracies limiting its applications. A systematic approach to overcome this issue is presented in this research paper. This will directly help the end users and the manufacturers of medical implants, wherein, better surface finish and dimensionally accurate components are expected.

A multi-criteria decision making method for vapor smoothening fused deposition modelling part

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sugavaneswarn M. ◽  
Prashanthi B. ◽  
John Rajan A.
Keyword(s):  
Decision Making ◽  
Surface Roughness ◽  
Process Parameters ◽  
Surface Finish ◽  
Orientation Angle ◽  
Multi Criteria Decision Making ◽  
Post Processing ◽  
Dimensional Error ◽  
Content Type ◽  
Fused Deposition

Purpose This paper aims to enhance the surface finish of the fused deposition modeling (FDM) part using the vapor smoothening (VS) post-processing method and to study the combined effect of FDM and VS process parameters on the quality of the part. Design/methodology/approach Analysis of variance method is used to understand the significance of the FDM and VS process parameters. Following this, the optimized parameter for multiple criteria response is reported using the technique for order preference by similarity to ideal solution. The process parameters alternatives are build orientation angle, build surface normal and exposure time and the criteria are surface roughness and dimensional error percentage. Findings The result observed contradicts the result reported on the independent parameter optimization of FDM and VS processes. There is a radical improvement in the surface finish on account of the coating process and an increase in the exposure time results in the decrease of the surface roughness. Minimum surface roughness of 0.11 µm is observed at 1,620 build angle and the least dimensional error of 0.01% is observed at build orientation angle 540. The impact of VS on the up-facing surface is different from the down-facing surface due to the removal of support material burrs and the exposure of the surface to vapor direction. Originality/value A study on the multi-criteria decision-making to ascertain the effect of post-processing on FDM component surface normal directed both to downward (build angle 0°–90°) and to upward (build angle 99°–180°) are reported for the first time in this article. The data reported for the post-processed FDM part at the build angle 0°–180° can be used as a guideline for selecting the optimal parameter and for assigning appropriate tolerance in the CAD model.

The mechanism of process parameters influencing the AlSi10Mg side surface quality fabricated via laser powder bed fusion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shimin Dai ◽  
Hailong Liao ◽  
Haihong Zhu ◽  
Xiaoyan Zeng
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Process Parameters ◽  
Laser Power ◽  
Side Surface ◽  
Laser Powder Bed Fusion ◽  
Scanning Velocity ◽  
Content Type ◽  
Powder Bed

Purpose For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is generally adopted at the parts’ outline to enhance the side surface quality. However, the side surface roughness (Ra) is still larger than 10 microns even with contour in previous studies. The purpose of this paper is to study the influence of contour process parameters, laser power and scanning velocity on the side surface quality of the AlSi10Mg sample. Design/methodology/approach Using L-PBF technology to manufacture AlSi10Mg samples under different contour process parameters, use a laser confocal microscope to capture the surface information of the samples, and obtain the surface roughness Ra and the maximum surface height Rz of each sample after analysis and processing. Findings The results show that the side surface roughness decreases with the increase of the laser power at the fixed scanning velocity of 1,000 mm/s, the side surface roughness Ra stays within the error range as the contour velocity increases. It is found that the Ra increases with the scanning velocity increasing and the greater the laser power with the greater Ra increases when the laser power of contour process parameters is 300 W, 350 W and 400 W. The Rz maintain growth with the contour scanning velocity increasing at constant laser power. The continuous uniform contour covers the pores in the molten pool of the sample edge and thus increase the density of the sample. Two mechanisms named “Active adhesion” and “Passive adhesion” cause sticky powder. Originality/value Formation of a uniform and even contour track is key to obtain the good side surface quality. The side surface quality is determined by the uniformity and stability of the contour track when the layer thickness is fixed. These research results can provide helpful guidance to improve the surface quality of L-PBF manufactured parts.

scholarly journals Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 843 ◽  
Author(s):  
André Reck ◽  
André Till Zeuner ◽  
Martina Zimmermann
Keyword(s):  
Surface Roughness ◽  
Fatigue Strength ◽  
Surface Quality ◽  
Laser Cutting ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Surface Condition ◽  
Mechanical Polishing ◽  
Fatigue Properties ◽  
Post Processing

The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength.

Additive manufacturing using fine wire-based laser metal deposition

2019 ◽  
Vol 26 (3) ◽  
pp. 473-483
Author(s):  
Muhammad Omar Shaikh ◽  
Ching-Chia Chen ◽  
Hua-Cheng Chiang ◽  
Ji-Rong Chen ◽  
Yi-Chin Chou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
High Precision ◽  
Surface Finish ◽  
Dimensional Accuracy ◽  
Laser Metal Deposition ◽  
Cross Sectional ◽  
Content Type ◽  
Fine Wire

Purpose Using wire as feedstock has several advantages for additive manufacturing (AM) of metal components, which include high deposition rates, efficient material use and low material costs. While the feasibility of wire-feed AM has been demonstrated, the accuracy and surface finish of the produced parts is generally lower than those obtained using powder-bed/-feed AM. The purpose of this study was to develop and investigate the feasibility of a fine wire-based laser metal deposition (FW-LMD) process for producing high-precision metal components with improved resolution, dimensional accuracy and surface finish. Design/methodology/approach The proposed FW-LMD AM process uses a fine stainless steel wire with a diameter of 100 µm as the additive material and a pulsed Nd:YAG laser as the heat source. The pulsed laser beam generates a melt pool on the substrate into which the fine wire is fed, and upon moving the X–Y stage, a single-pass weld bead is created during solidification that can be laterally and vertically stacked to create a 3D metal component. Process parameters including laser power, pulse duration and stage speed were optimized for the single-pass weld bead. The effect of lateral overlap was studied to ensure low surface roughness of the first layer onto which subsequent layers can be deposited. Multi-layer deposition was also performed and the resulting cross-sectional morphology, microhardness, phase formation, grain growth and tensile strength have been investigated. Findings An optimized lateral overlap of about 60-70% results in an average surface roughness of 8-16 µm along all printed directions of the X–Y stage. The single-layer thickness and dimensional accuracy of the proposed FW-LMD process was about 40-80 µm and ±30 µm, respectively. A dense cross-sectional morphology was observed for the multilayer stacking without any visible voids, pores or defects present between the layers. X-ray diffraction confirmed a majority austenite phase with small ferrite phase formation that occurs at the junction of the vertically stacked beads, as confirmed by the electron backscatter diffraction (EBSD) analysis. Tensile tests were performed and an ultimate tensile strength of about 700-750 MPa was observed for all samples. Furthermore, multilayer printing of different shapes with improved surface finish and thin-walled and inclined metal structures with a minimum achievable resolution of about 500 µm was presented. Originality/value To the best of the authors’ knowledge, this is the first study to report a directed energy deposition process using a fine metal wire with a diameter of 100 µm and can be a possible solution to improving surface finish and reducing the “stair-stepping” effect that is generally observed for wires with a larger diameter. The AM process proposed in this study can be an attractive alternative for 3D printing of high-precision metal components and can find application for rapid prototyping in a range of industries such as medical and automotive, among others.

scholarly journals Influence of cutting parameters on surface quality when machining a CoCrWNi alloy

2018 ◽  
Vol 178 ◽  
pp. 01009
Author(s):  
Manuela-Roxana Dijmărescu ◽  
Ioan-Cristian Tarbă ◽  
Maria-Cristina Dijmărescu ◽  
Vlad Gheorghiţă
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Quality ◽  
Cutting Parameters ◽  
Medical Applications ◽  
Medical Implants

Due to their excellent biocompatibility and mechanical properties, the use of Co-Cr based alloys in medical applications has increased substantially. An important characteristic of the medical implants is their surface quality, this being a significant constraint when machining this kind of products. The aim of this paper is to present a research conducted in order to determine and expose the influence of turning cutting parameters on the surface roughness of a CoCrWNi alloy.

Fabrication of bulk alumina structures with humidity sensing capabilities using direct ink write technique

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anabel Renteria ◽  
Luisa F. Garcia ◽  
Jorge A. Diaz ◽  
Luis C. Delfin ◽  
Jaime E. Regis ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Post Processing ◽  
Humidity Sensors ◽  
Moisture Sensitivity ◽  
Humidity Sensing ◽  
Content Type ◽  
Lattice Design ◽  
Processing Treatment ◽  
Binder Ratio ◽  
Order Of Magnitude

Purpose The purpose of this study is to evaluate different 3D structures for humidity sensing that will enable the fabrication of complex geometries with high moisture sensitivity. Design/methodology/approach Humidity sensors based on alumina ceramics were fabricated using direct ink write (DIW) technique. Different engineered surface area, polymer binder ratio and post-processing treatment were considered to increase moisture sensitivity. Findings It was found that the binder ratio plays an important role in controlling the rheology of the paste during printing and determining the pore size after post-processing treatment. The sensibility of the fabricated humidity sensor was investigated by measuring its capacitance response toward relative humidity (RH) varying from 40% to 90% RH at 25°C. It is shown that using 3D lattice design, printed alumina humidity sensor could improve sensitivity up to 31.6 pF/RH%, over an order of magnitude higher than solid alumina. Originality/value Most of the alumina humidity sensors available are films in nature because of manufacturing difficulties, which limited its potential of higher sensitivity, and thus broader applications. In this paper, a novel 3D alumina humidity sensor was fabricated using DIW 3D printing technology.

Effect of cold vapour treatment on geometric accuracy of fused deposition modelling parts

2017 ◽  
Vol 23 (6) ◽  
pp. 1226-1236 ◽  
Author(s):  
Ashu Garg ◽  
Anirban Bhattacharya ◽  
Ajay Batish
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Fused Deposition Modelling ◽  
Curved Surfaces ◽  
Geometric Accuracy ◽  
Content Type ◽  
Fused Deposition ◽  
Cold Vapour ◽  
Side Face ◽  
Functional Components

Purpose The purpose of this paper is to investigate the influence of low-cost chemical vapour treatment process on geometric accuracy and surface roughness of different curved and freeform surfaces of fused deposition modelling (FDM) specimens build at different part building orientations. Design/methodology/approach Parts with different primitive and curved surfaces are designed and modelled to build at three different part orientations along X orientation (vertical position resting on side face), Y orientation (horizontal position resting on base) and Z orientation (upright position). Later, the parts are post-processed by cold vapours of acetone. Geometric accuracy and surface roughness are measured both before and after the chemical treatment to investigate the change in geometric accuracy, surface roughness of FDM parts. Findings The results indicate that surface roughness is reduced immensely after cold vapour treatment with minimum variation in geometric accuracy of parts. Parts build vertically over its side face (X orientation) provides the overall better surface finish and geometric accuracy. Originality/value The present study provides an approach of post-built treatment for FDM parts and observes a significant improvement in surface finish of the components. The present approach of post-built treatment can be adopted to enhance the surface quality as well as to achieve desired geometric accuracy for different primitive, freeform/curved surfaces of FDM samples suitable for functional components as well as prototypes.

scholarly journals Impact of vapor polishing on surface quality and mechanical properties of extruded ABS

2018 ◽  
Vol 24 (2) ◽  
pp. 501-508 ◽  
Author(s):  
Clayton Neff ◽  
Matthew Trapuzzano ◽  
Nathan B. Crane
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Quality ◽  
Complex Geometry ◽  
Substantial Impact ◽  
Solvent Vapor ◽  
Content Type ◽  
Minimal Impact ◽  
End Use ◽  
Traditional Manufacturing

Purpose Additive manufacturing (AM) is readily capable of producing models and prototypes of complex geometry and is advancing in creating functional parts. However, AM processes typically underperform traditional manufacturing methods in mechanical properties, surface roughness and hermeticity. Solvent vapor treatments (vapor polishing) are commonly used to improve surface quality in thermoplastic parts, but the results are poorly characterized. Design/methodology/approach This work quantifies the surface roughness change and also evaluates the effect on hermeticity and mechanical property impacts for “as-printed” and acetone vapor-polished ABS tensile specimens of 1-, 2- and 4-mm thicknesses produced by material extrusion (FDM). Findings Vapor polishing proves to decrease the power spectral density for surface roughness features larger than 20 µm by a factor of 10× and shows significant improvement in hermeticity based on both perfluorocarbon gross leak and pressure leak tests. However, there is minimal impact on mechanical properties with the thin specimens showing a slight increase in elongation at break but decreased elastic modulus. A bi-exponential diffusion decay model for solvent evaporation suggest a thickness-independent and thickness-dependent time constant with the latter supporting a plasticizing effect on mechanical properties. Originality/value The contributions of this work show vapor polishing can have a substantial impact on the performance for end-use application of ABS FDM components.

Magnetorheological finishing of silicon for nanometric surface generation: An experimental and simulation study

2018 ◽  
Vol 29 (11) ◽  
pp. 2456-2464 ◽  
Author(s):  
Neha Khatri ◽  
Suman Tewary ◽  
Xavier J Manoj ◽  
Harry Garg ◽  
Vinod Karar
Keyword(s):  
Molecular Dynamics ◽  
Surface Roughness ◽  
Surface Quality ◽  
Surface Finish ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Surface Generation ◽  
Magnetorheological Finishing ◽  
X Ray ◽  
Finishing Process

Silicon mirrors are essential for guiding the X-ray beam and focusing it to a specific location. These mirrors using total internal reflection require super smooth surface finish due to small wavelength of X-ray. Magnetorheological finishing is a computer-controlled technique used in the production of high-quality optical lenses. This process utilizes polishing slurries based on magnetorheological fluids, whose viscosity changes with the change in magnetic field. In this work, polishing potential of silicon mirrors by magnetorheological finishing process is examined to achieve nanometric surface finish for X-ray applications. The individual effect of parameters such as magnetizing current, working gap, rotational speed on surface roughness is investigated, and optimized parameters are identified. To investigate the physical essence underlying magnetorheological finishing process, the molecular dynamics simulations are used. Molecular dynamics simulation is used to study the atomic-scale removal mechanism of single-crystalline silicon in magnetorheological finishing process and attention is paid to study the effect of gap between the tool and the workpiece on surface quality. The outcome is promising and the final surface roughness achieved is as low as 6.4 nm. The surface quality is analyzed in terms of arithmetic roughness, power spectral density, and image analysis of scanning electron microscopy for uniform evaluation.

Surface quality optimization of CFRP plates drilled with standard and step drill bits using TAGUCHI, TOPSIS and AHP method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gökhan Sur ◽  
Ömer Erkan
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Thrust Force ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Tool Geometry ◽  
Ahp Method ◽  
Content Type ◽  
Delamination Factor ◽  
Drill Bits

Purpose Drilling of carbon fiber reinforced plastic (CFRP) composite plates with high surface quality are of great importance for assembly operations. The article aims to optimize the drill geometry and cutting parameters to improve the surface quality of CFRP composite material. In this study, CFRP plates were drilled with uncoated carbide drill bits with standard and step geometry. Thus, the effects of standard and step drill bits on surface quality have been examined comparatively. In addition, optimum output parameters were determined by Taguchi, ANOVA and multiple decision-making methods. Design/methodology/approach Drill bit point angles were selected as 90°, 110° and 130°. In cutting parameters, three different cutting speeds (25, 50 and 75 m/min) and three different feeds (0.1, 0.15 and 0.2 mm/rev) were determined. L18 orthogonal sequence was used with Taguchi experimental design. Three important output parameters affecting the surface quality are determined as thrust force, surface roughness and delamination factor. For each output parameter, the effects of drill geometry and cutting parameters were evaluated. Input parameters affecting output parameters were analyzed using the ANOVA method. Output parameters were estimated by creating regression equations. Weights were determined using the analytic hierarchy process (AHP) method, and multiple output parameters were optimized using technique for order preference by Similarity to An ideal solution (TOPSIS). Findings It has been determined from the experimental results that step drills generate smaller thrust forces than standard drills. However, it has been determined that it creates greater surface roughness and delamination factor. From the Taguchi analysis, the optimum input parameters for Fz step tool geometry, 90° point angle, 75 m/min cutting speed and 0.1 mm/rev feed. For Fd, are standard tool geometry, 90° point angle, 25 m/min cutting speed and 0.1 mm/rev feed and for Ra, are standard tool geometry, 130° point angle, 25 m/min cutting speed and 0.1 mm/rev feed. ANOVA analysis determined that the most important parameter on Fd is the tip angle, with 56.33%. The most important parameter on Ra and Fz was found to be 40.53% and 77.06% tool geometry, respectively. As a result of the optimization with multiple criteria decision-making methods, the test order that gave the best surface quality was found as 4–1-9–5-8–17-2–13-6–16-18–15-11–10-3–12-14. The results of the test number 4, which gives the best surface quality, namely, the thrust force is 91.86 N, the surface roughness is 0.75 µm and the delamination factor is 1.043. As a result of experiment number 14, which gave the worst surface quality, the thrust force was 149.88 N, the surface roughness was 3.03 µm and the delamination factor was 1.163. Practical implications Surface quality is an essential parameter in the drilling of CFRP plates. Cutting tool geometry comes first among the parameters affecting this. Therefore, different cutting tool geometries are preferred. A comparison of these cutting tools is discussed in detail. On the other hand, thrust force, delamination factor and surface roughness, which are the output parameters that determine the surface quality, have been optimized using the TOPSIS and AHP method. In this way, this situation, which seems complicated, is presented in a plain and understandable form. Originality/value In the experiments, cutting tools with different geometries are included. Comparatively, its effects on surface quality were examined. The hole damage mechanism affecting the surface quality is discussed in detail. The results were optimized by evaluating Taguchi, ANOVA, TOPSIS and AHP methods together.

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