Investigations for partial denture casting by fused deposition modelling-assisted chemical vapour smoothing

2020 ◽  
Vol 40 (5) ◽  
pp. 745-754
Author(s):  
Gurpartap Singh ◽  
Rupinder Singh ◽  
S.S. Bal

Purpose The purpose of this study is to investigate dimensional accuracy (Δd), surface roughness (Ra) and micro hardness (HV) of partial dentures (PD) prepared with synergic combination of fused deposition modelling (FDM) assisted chemical vapour smoothing (CVS) patterns and conventional dental casting (DC) from multi-factor optimization view point. Design/methodology/approach The master pattern for PD was prepared with acrylonitrile butadiene styrene (ABS) thermoplastic on FDM set-up (one of the low cost additive manufacturing process) followed by CVS process. The final PD as functional prototypes was casted with nickel–chromium-based (Ni-Cr) alloy by varying Ni% (Z). The other input parameters were powder to water ratio P/W (X) and pH value (Y) of water used. Findings The results of this study suggest that for controlling the Δd and Ra of the PD, most important factor is X, followed by Z. For hardness of PD, the most important factor is Z. But from overall optimization viewpoint, the best settings are X-100/12, Y-10 and Z-61% (in Ni-Cr alloy). Further, based upon X-bar chart (for HV), the FDM-assisted DC process used for preparation of PD is statistically controlled. Originality/value This study highlights that PD prepared with X-100/12, Y-10 and Z-61% gives overall better results from multi-factor optimization view point. Finally, X-bar chart has been plotted to understand the statistical nature of the synergic combination of FDM, CVS and DC.

2018 ◽  
Vol 2 (2) ◽  
pp. 115-137 ◽  
Author(s):  
Ranvijay Kumar ◽  
Rupinder Singh ◽  
Ilenia Farina

Purpose Three-dimensional printing (3DP) is an established process to print structural parts of metals, ceramic and polymers. Further, multi-material 3DP has the potentials to be a milestone in rapid manufacturing (RM), customized design and structural applications. Being compatible as functionally graded materials in a single structural form, multi-material-based 3D printed parts can be applied in structural applications to get the benefit of modified properties. Design/methodology/approach The fused deposition modelling (FDM) is one of the established low cost 3DP techniques which can be used for printing functional/ non-functional prototypes in civil engineering applications. Findings The present study is focused on multi-material printing of primary recycled acrylonitrile butadiene styrene (ABS), polylactic acid (PLA) and high impact polystyrene (HIPS) in composite form. Thermal (glass transition temperature and heat capacity) and mechanical properties (break load, break strength, break elongation, percentage elongation at break and Young’s modulus) have been analysed to observe the behaviour of multi-material composites prepared by 3DP. This study also highlights the process parameters optimization of FDM supported with photomicrographs. Originality/value The present study is focused on multi-material printing of primary recycled ABS, PLA and HIPS in composite form.


2018 ◽  
Vol 24 (6) ◽  
pp. 921-934 ◽  
Author(s):  
Mohammad Abu Hasan Khondoker ◽  
Asad Asad ◽  
Dan Sameoto

Purpose This paper aims to target to print functionally gradient materials (FGM) devices made of immiscible polymers in multi-material fused deposition modelling (FDM) systems. The design is intended to improve adhesion of dissimilar thermoplastics without the need for chemical compatibilization so that filaments from many different sources can be used effectively. Therefore, there is a need to invent an alternative solution for printing multiple immiscible polymers in an FDM system with the desired adhesion. Design/methodology/approach In this study, the authors have developed a bi-extruder for FDM systems which can print two thermoplastics through a single nozzle with a static intermixer to enhance bonding between input materials. The system can also change the composition of extrudates continuously. Findings The uniqueness of this extruder is in its easy access to the internal channel so that a static intermixer can be inserted, enabling deposition of mechanically interlocked extrudates composed of two immiscible polymers. Without this intermixer, the bi-extruder extrudes with simple side-by-side co-extrusion having no mechanical interlocking. The bi-extruder was characterized by printing objects using pairs of materials including polylactic acid, acrylonitrile butadiene styrene and high impact polystyrene. Microscope images of the cross-sections of the extrudates confirm the ability of this bi-extruder to control the composition as desired. It was also found that the mechanically interlocked extrudates composed of two immiscible polymers substantially reduces adhesion failures within and between filaments. Originality/value In this study, the first-ever FDM extruder with a mechanical blending feature next to the nozzle has been designed and used to successfully print FGM objects with improved mechanical properties.


2019 ◽  
Vol 26 (2) ◽  
pp. 288-298 ◽  
Author(s):  
Oğuzhan Emre Akbaş ◽  
Onur Hıra ◽  
Sahar Zhiani Hervan ◽  
Shahrad Samankan ◽  
Atakan Altınkaynak

Purpose This paper aims to analyze experimentally and numerically the effect of the nozzle temperature and feed rates on the dimensions of the fused deposition modeling (FDM) polymer parts. Design/methodology/approach In total, 30 strips per sample were printed with the same width as the nozzle diameter. The strips were printed with one vertical movement of the nozzle head. The width of the strips was measured with a caliper at five locations. A linear regression model was created based on the experimental data to understand the correlation between the strip width deviation and the parameters of interest. Numerical simulations were performed to predict the swell of the polymer exiting the nozzle using finite element method combined with level set method. The experimental results were then used to validate the models. Findings The average accuracy of polylactic acid (PLA) samples was better than that of acrylonitrile butadiene styrene (ABS) samples. The average strip width had a tendency to increase with increasing temperature for PLA samples, whereas ABS samples showed mixed behavior. The strip width decreased with increasing feed rate for most cases. The measurement positions had a major effect on strip width when compared to nozzle temperature and feed rate. The numerical model predictions were in good agreement with the experimental data. A few discrepancies were observed at high feed rates and nozzle temperatures. Originality/value This study will contribute to gaps in knowledge regarding the effect of processing conditions on dimensional accuracy of FDM-printed parts. The developed numerical model can be efficiently used to predict the dimensional accuracy of FDM-printed parts.


Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 651 ◽  
Author(s):  
David Moises Baca Lopez ◽  
Rafiq Ahmad

The application of single homogeneous materials produced through the fused deposition modelling (FDM) technology restricts the production of high-level multi-material components. The fabrication of a sandwich-structured specimen with different material combinations using conventional thermoplastics such as poly (lactic acid) (PLA), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) through the filament-based extrusion process can demonstrate an improvement on its properties. This paper aims to assess among these materials, the best material sandwich-structured arrangement design, to enhance the mechanical properties of a part and to compare the results with the homogeneous materials selected. The samples were subjected to tensile testing to identify the tensile strength, elongation at break and Young’s modulus of each material combination. The experimental results demonstrate that applying the PLA-ABS-PLA sandwich arrangement leads to the best mechanical properties between these materials. This study enables users to consider sandwich structure designs as an alternative to manufacturing multi-material components using conventional and low-cost materials. Future work will consider the flexural tests to identify the maximum stresses and bending forces under pressure.


2019 ◽  
Vol 48 (1) ◽  
pp. 18-23
Author(s):  
Nishant Ranjan ◽  
Rupinder Singh ◽  
IPS Ahuja

Fused deposition modelling (FDM) is one of the low cost additive manufacturing (AM) process. The feed stock filament of FDM is the only consumable in the process and by preparing (in-house) bio compatible feed stock filament the application domain can be increased. Some studies have reported the use of twin screw extrusion (TSE) process for preparation of bio compatible feed stock filament (comprising of polyvinyl chloride (PVC) and polypropylene (PP) and hydroxyapatite (HAp) particles) with improved mechanical, dimensional and thermal properties, for commercial FDM setup. But hitherto very less has been reported on process capability of in-house prepared biocompatible feed stock filament. In the present work statistical analysis (for tensile strength, hardness and dimensional accuracy) has been performed for investigations of process capability. The results have been also supported by control charts (X-chart and R-chart) based upon the best feedstock filament wire.


2019 ◽  
Vol 821 ◽  
pp. 174-180
Author(s):  
Ramil Kesvarakul ◽  
Khompee Limpadapun

Fused Deposition Modelling (FDM) has been extensively used in low-cost printers. However, the fundamental working principle (layered manufacturing) is resulted in the poor quality of the surface texture, the dimensional inaccuracy of fabricated parts, the limits its domain all issues often take place in precision industrial applications. In this paper, initially FDM based acrylonitrile butadiene styrene (ABS) model have been fabricated. In the post-processing stage, the vapor of acetone has been applied to the specimen. Then the changes in the surface finish and surface roughness have been investigated. The study highlighted that the post-processing of ABS specimen with acetone vapor treatment resulted in dramatic improvement of surface finish. Finally, parameter setting that gave the acceptable results while considering all the responses simultaneously.


2019 ◽  
Vol 25 (4) ◽  
pp. 765-774 ◽  
Author(s):  
Prithvirajan R. ◽  
Sugavaneswaran M. ◽  
Sathishkumar N. ◽  
Arumaikkannu G.

Purpose Custom-designed metal bellows require alternate ways to produce the die to shorten lead time. The purpose of this study is to explore the possibility of using Additive Manufactured (AM) polymer die as direct rapid tool (RT) for metal bellow hydroforming. Design/methodology/approach Finite element analysis (FEA) was used to simulate bellow forming and to evaluate the compatibility of AM die. Fused deposition modelling (FDM) technique is used to fabricate die with Acrylonitrile Butadiene Styrene (ABS) material. To validate, the width of the metal bellow convolutions obtained from the FEA simulation is compared with convolution formed during the experiment. Findings FDM-made die can be used for a short production run of bellow hydroforming. FEA simulation shows that stress developed in some regions of die is less and these regions have potential for material reduction. Use of RT for this particular application is limited by the die material, forming pressure, width, convolution span and material of bellow. This supports the importance of FEA validation of RT before fabrication to evaluate and redesign die for the successful outcome of the tool. Research limitations/implications The given methodology may be followed to design a RT with minimum material consumption for bellow forming application. Whenever there is a change in bellow design or the die material, simulation has to be done to evaluate the capability of the die. As this study was focused on a short production run for manufacturing one or few bellows, the die life is not a significant factor. Originality/value This paper demonstrates about rapid tooling for metal bellow manufacturing using FDM technique for low volume production. Further, FEA is used to identify low stress regions and redesign the die for material reduction before die manufacturing. AM die can be used for developing customized metal bellow for applications such as defense, aerospace, automobiles, etc.


2018 ◽  
Vol 24 (3) ◽  
pp. 615-622 ◽  
Author(s):  
Piotr Wolszczak ◽  
Krystian Lygas ◽  
Mateusz Paszko ◽  
Radoslaw A. Wach

Purpose The paper aims to investigate the problem of heat distribution in FDM 3D printing. The temperature distribution of the material is important because of the occurrence of shrinkage and crystallization phenomena that affect the dimensional accuracy and strength of the material. Design/methodology/approach The study uses a thermoplastic material (polylactide) and a test stand equipped with a 3D printer adapted to perform thermographic observations. The main source of heat in the study was a molten laminate material and a hot-end head. Findings When the material is molten at the temperature of 190°C, the temperature of a previous layer increases above the glass transition point (Tg = 64.8°C) and reaches to about 80°C. In addition, at the boundary of the layers, there occurs a permanent bonding of the consecutive layers because of their partial melting. The paper also reports the results of porosity of PLA samples printed at the temperature ranging between 205 and 255°C. The degree of porosity depends on the temperature of the extruded material. Practical implications The results may be helpful for designers of various printed parts and construction engineers of printing heads and 3D printer chambers. Originality/value Thermograms of material layers with a height of 0.3 mm are obtained using a thermal imaging camera with a lens for macro magnification (43 pixels/mm).


2020 ◽  
Vol 26 (10) ◽  
pp. 1733-1738
Author(s):  
André Luiz Alves Guimarães ◽  
Vicente Gerlin Neto ◽  
Cesar Renato Foschini ◽  
Maximiliano dos Anjos Azambuja ◽  
Luiz Antonio Vasques Hellmeister

Purpose The purpose of this paper is to investigate and discuss the influence of printing parameters on the mechanical properties of acrylonitrile butadiene styrene (ABS) print by fused deposition modelling (FDM). The mechanical properties of ABS are highly influenced by printing parameters, and they determine the final product quality of printed pieces. Design/methodology/approach For the paper’s purpose, five main parameters (extrusion temperature, infill pattern, air gap, printing speed and layer thickness) were selected and varied during ABS printing on an open-source and self-replicable FDM printer. Three different colors of commercially available ABS were also used to investigate color and printing parameter’s influence on the tensile strength. Findings The research results suggest that two parameters (infill pattern and layer thickness) were most influential on the mechanical properties of print ABS, being able to enhance its tensile strength. Another key influential factor was material color selected prior to printing, which influenced the tensile strength of the print specimen. Originality/value This study provides information on print parameters’ influence on the tensile strength of ABS print on replicable open-source three-dimensional (3D) printers. It also suggests the influence of materials’ color on print pieces’ tensile strength, indicating a new parameter for materials selection for 3D printing.


2017 ◽  
Vol 23 (6) ◽  
pp. 1043-1050 ◽  
Author(s):  
Sergio Pietanza ◽  
Donato Sorgente ◽  
Gianluca Percoco

Purpose In this paper, the authors propose an experimental set-up to study the chemical vapour polishing technique confining pure dimethylketone atmosphere at a fixed temperature in a vacuum chamber. The purpose of this paper is to improve conventional vapour treatments lowering the amount of solvent, lowering time and temperature needed and improving the environmental impact of the technique. Design/methodology/approach A factorial design of experiments is adopted to understand the effect of the treatment on roughness and on the surface morphology of treated specimens. Findings The proposed method improves several aspects of well-known methods based on water–dimethylketone liquid solution such as: no interaction between water and workpiece and higher capability of process management. It also improves several aspects of well-known methods based on vapour, lowering the amount of solvent, time and temperature compared to conventional vapour treatments. Originality/value Chemical vapour polishing is a well-known technique for smoothing additive manufactured acrylonitrile butadiene styrene (ABS) parts. Several data and users' experiences are available on the Web about this topic. In recent scientific literature, a few papers are available about this topic, dealing with how process parameters affect the final surface roughness. In the present paper, the authors propose to improve the process performing the process using dimethylketone into a vacuum chamber. The main advantages are the significant reduction of the solvent needed to perform the process and lower time needed to obtain same results as atmospheric pressure treatments.


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