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Article
Publication date: 2 November 2020

Alasdair Soja, Jun Li, Seamus Tredinnick and Tim Woodfield

Additive manufacturing (AM) has the potential to revolutionise the fabrication of complex surgical instruments. However, AM parts typically have a higher surface roughness…

Abstract

Purpose

Additive manufacturing (AM) has the potential to revolutionise the fabrication of complex surgical instruments. However, AM parts typically have a higher surface roughness compared to machined or fine cast parts. High surface roughness has important implications for surgical instruments, particularly in terms of cleanliness and aesthetic considerations. In this study, bulk surface finishing methods are described to produce end-use selective laser melting parts.

Design/methodology/approach

The aim was to achieve a surface finish as close as possible to machined parts (Ra = 0.9 µm, Wa = 0.2 µm, Pv = 7.3 µm). A sample coupon was designed to systematically evaluate different finishing techniques. Processes included bulk finishing, blasting and centrifugal finishing methods on individual parts, as well as heat treatment before and after surface finishing.

Findings

Abrasive blasting or centrifugal finishing alone was not adequate to achieve an end-use surface finish. White oxide vapour blasting at high water pressure was the most effective of the abrasive blasting processes. For centrifugal finishing, a 4 h runtime resulted in an acceptable reduction in surface roughness (Ra = 2.9 µm, Wa = 2.0 µm, Pv = 34.6 µm: inclined surface [30°]) while not significantly increasing part radii. The combination of finishing methods resulting in the smoothest surfaces was white oxide blasting followed by 4 h of centrifugal finishing and a final glass bead blast (Ra = 0.6 µm, Wa = 0.9 µm, Pv = 6.9 µm: inclined surface [30°]). The order of these methods was important because white oxide blasting was significantly less effective when applied after the centrifugal finishing.

Originality/value

Collectively, these results describe the development of a practical bulk finishing method for stainless steel surgical instruments produced by AM.

Details

Rapid Prototyping Journal, vol. 27 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 2 January 2018

Jasgurpreet Singh Chohan, Rupinder Singh and Kamaljit Singh Boparai

This paper aims to focus on the changes in thermal and surface characteristics of acrylonitrile butadiene styrene (ABS) material when exposed to chemical vapours for…

Abstract

Purpose

This paper aims to focus on the changes in thermal and surface characteristics of acrylonitrile butadiene styrene (ABS) material when exposed to chemical vapours for surface finishing. The poor surface finish and the dimensional accuracy of the fused deposition modelling parts (of ABS material) because of the stair-stepping hinder their use for rapid tooling applications, which can be improved by vapour finishing process. The differential scanning calorimetry (DSC) tests are performed to investigate the thermal behaviour of ABS thermoplastic after vapour finishing.

Design/methodology/approach

The hip prosthesis replica has been used to highlight the efficacy of chemical finishing process for intricate and complex geometries. The replicas are treated with chemical vapours for different durations. The DSC tests are performed along with surface roughness, surface hardness and dimensional measurements of exposed replicas and compared with unexposed replica.

Findings

The longer finishing time, i.e. 20 s, manifested higher melting peak temperature, higher melting enthalpy and higher heat capacity along with smoother and harder surface as compared with unexposed replica. The finishing process enhanced the bonding strength and the heat-bearing capacity of ABS material. The vapour finishing process enhanced the thermal stability of the material which may extend its sustainability at higher temperatures.

Practical implications

The improved thermal stability of ABS thermoplastic after chemical vapour finishing has been demonstrated. This advancement allows the use of ABS in functional tooling suitable for small production runs with higher flexibility and lead time savings.

Originality/value

The heat effects associated with phase transitions as a function of temperature are studied in case of replicas finished with chemical vapours. The relationship between melting enthalpy and surface characteristics has been ascertained.

Details

Rapid Prototyping Journal, vol. 24 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 31 August 2021

Nitin Dixit, Varun Sharma and Pradeep Kumar

The surface roughness of additively manufactured parts is usually found to be high. This limits their use in industrial and biomedical applications. Therefore, these parts…

Abstract

Purpose

The surface roughness of additively manufactured parts is usually found to be high. This limits their use in industrial and biomedical applications. Therefore, these parts required post-processing to improve their surface quality. The purpose of this study is to finish three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) parts using abrasive flow machining (AFM).

Design/methodology/approach

A hydrogel-based abrasive media has been developed to finish 3D printed parts. The developed abrasive media has been characterized for its rheology and thermal stability using sweep tests, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The ABS and PLA cylindrical parts have been prepared using fused deposition modeling (FDM) and finished using AFM. The experiments were designed using Taguchi (L9 OA) method. The effect of process parameters such as extrusion pressure (EP), layer thickness (LT) and abrasive concentration (AC) was investigated on the amount of material removed (MR) and percentage improvement in surface roughness (%ΔRa).

Findings

The developed abrasive media was found to be effective for finishing FDM printed parts using AFM. The microscope images of unfinished and finished showed a significant improvement in surface topography of additively manufactures parts after AFM. The results reveal that AC is the most significant parameter during the finishing of ABS parts. However, EP and AC are the most significant parameters for MR and %ΔRa, respectively, during the finishing of PLA parts.

Practical implications

The FDM technology has applications in the biomedical, electronics, aeronautics and defense sectors. PLA has good biodegradable and biocompatible properties, so widely used in biomedical applications. The ventilator splitters fabricated using FDM have a profile similar to the shape used in the present study.

Research limitations/implications

The present study is focused on finishing FDM printed cylindrical parts using AFM. Future research may be done on the AFM of complex shapes and freeform surfaces printed using different additive manufacturing (AM) techniques.

Originality/value

An abrasive media consists of xanthan gum, locust bean gum and fumed silica has been developed and characterized. An experimental study has been performed by combining printing parameters of FDM and finishing parameters of AFM. A comparative analysis in MR and %ΔRa has been reported between 3D printed ABS and PLA parts.

Details

Rapid Prototyping Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 9 April 2018

Harlal S. Mali, Bhargav Prajwal, Divyanshu Gupta and Jai Kishan

The purpose of this paper is to study the integration between fused deposition modeling (FDM) technology and abrasive flow machining process to improve the surface quality…

Abstract

Purpose

The purpose of this paper is to study the integration between fused deposition modeling (FDM) technology and abrasive flow machining process to improve the surface quality of FDM printed parts. FDM process has some limitations in terms of accuracy and surface finish. Hence, post-processing operations are essential to increase the quality of the part.

Design/methodology/approach

Initially, a sustainable polymer abrasive gel-based media (SPAGM) using natural polymer and natural additives (waste vegetable oil) was prepared using different combinations of (abrasive mesh size, percentage of abrasives and percentage of liquid synthesizer); then the characterization of media was done to check various properties. As media is an essential part in the process which helps in increase the surface finish, it needs to have some desired characteristics such as the following: the developed SPAG needs to hold the abrasives; its viscosity has to be medium so that it can easily flow through the machine; and its thermal stability caused by the increase in the temperature during various cycles of operation. For that, it is characterized rheologically as well as thermally to find its various properties.

Findings

Experiments were performed on FDM-printed parts using an L9 orthogonal array with different parameters to find their effect on the workpiece. Scanning electron microscope images of SGAPM showed sharp edges of abrasive particles and bonding pattern between polymer chain molecules. Good surface finish and material removal rate (MRR) was observed at high pressure and long finishing time with 50 per cent abrasive concentration.

Originality/value

The authors confirm that this work is original and has neither been published elsewhere nor is it currently under consideration for publication elsewhere.

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Article
Publication date: 18 April 2017

Jasgurpreet Singh Chohan and Rupinder Singh

The purpose of this paper is to review the various pre-processing and post-processing approaches used to ameliorate the surface characteristics of fused deposition…

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1715

Abstract

Purpose

The purpose of this paper is to review the various pre-processing and post-processing approaches used to ameliorate the surface characteristics of fused deposition modelling (FDM)-based acrylonitrile butadiene styrene (ABS) prototypes. FDM being simple and versatile additive manufacturing technique has a calibre to comply with present need of tailor-made and cost-effective products with low cycle time. But the poor surface finish and dimensional accuracy are the primary hurdles ahead the implementation of FDM for rapid casting and tooling applications.

Design/methodology/approach

The consequences and scope of FDM pre-processing and post-processing parameters have been studied independently. The comprehensive study includes dominance, limitations, validity and reach of various techniques embraced to improve surface characteristics of ABS parts. The replicas of hip implant are fabricated by maintaining the optimum pre-processing parameters as reviewed, and a case study has been executed to evaluate the capability of vapour smoothing process to enhance surface finish.

Findings

The pre-processing techniques are quite deficient when different geometries are required to be manufactured within limited time and required range of surface finish and accuracy. The post-processing techniques of surface finishing, being effective disturbs the dimensional stability and mechanical strength of parts thus incapacitates them for specific applications. The major challenge for FDM is the development of precise, automatic and controlled mass finishing techniques with low cost and time.

Research limitations/implications

The research assessed the feasibility of vapour smoothing technique for surface finishing which can make consistent castings of customized implants at low cost and shorter lead times.

Originality/value

The extensive research regarding surface finish and dimensional accuracy of FDM parts has been collected, and inferences made by study have been used to fabricate replicas to further examine advanced finishing technique of vapour smoothing.

Details

Rapid Prototyping Journal, vol. 23 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 5 May 2021

Pedram Parandoush, Palamandadige Fernando, Hao Zhang, Chang Ye, Junfeng Xiao, Meng Zhang and Dong Lin

Additively manufactured objects have layered structures, which means post processing is often required to achieve a desired surface finish. Furthermore, the additive…

Abstract

Purpose

Additively manufactured objects have layered structures, which means post processing is often required to achieve a desired surface finish. Furthermore, the additive nature of the process makes it less accurate than subtractive processes. Hence, additive manufacturing techniques could tremendously benefit from finishing processes to improve their geometric tolerance and surface finish.

Design/methodology/approach

Rotary ultrasonic machining (RUM) was chosen as a finishing operation for drilling additively manufactured carbon fiber reinforced polymer (CFRP) composites. Two distinct additive manufacturing methods of fused deposition modeling (FDM) and laser-assisted laminated object manufacturing (LA-LOM) were used to fabricate CFRP plates with continuous carbon fiber reinforcement. The influence of the feedrate, tool rotation speed and ultrasonic power of the RUM process parameters on the aforementioned quality characteristics revealed the feasibility of RUM process as a finishing operation for additive manufactured CFRP.

Findings

The quality of drilled holes in the CFRP plates fabricated via LA-LOM was supremely superior to the FDM counterparts with less pullout delamination, smoother surface and less burr formation. The strong interfacial bonding in LA-LOM proven to be superior to FDM was able to endure higher cutting force of the RUM process. The cutting force and cutting temperature overwhelmed the FDM parts and induced higher surface damage.

Originality/value

Overall, the present study demonstrates the feasibility of a hybrid additive and subtractive manufacturing method that could potentially reduce cost and waste of the CFRP production for industrial applications.

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Article
Publication date: 17 October 2008

G. Milighetti and H‐B. Kuntze

Autonomous robot‐based finishing of surfaces with a reduction of the programming effort can be achieved by teaching the desired trajectory locally in the object reference…

Abstract

Purpose

Autonomous robot‐based finishing of surfaces with a reduction of the programming effort can be achieved by teaching the desired trajectory locally in the object reference frame. Thus, the flexibility of the programmed task increases and also moving surfaces can be finished. This paper aims to focus on this control concept.

Design/methodology/approach

The developed concept relies both on the use of a new slip sensor which is able to measure relative motion between the robot end‐effector and the machined object surface as well as on a continuous slip and force control algorithm. First experimental results were used to validate the concept.

Findings

The presented results were promising enough to encourage the application of the proposed concept scheme in connection with the slip sensor in industrial finishing applications.

Research limitations/implications

The first investigations provide a basis for the development of more accurate software solutions in order to optimise the performances of the slip sensor.

Practical implications

The developed slip sensor provides a cheap and flexible solution for measuring relative motion between tool and surface. Combined with the use of a force sensor, the proposed scheme can be introduce more autonomy in industrial application like polishing or deburring.

Originality/value

The paper introduces a novel slip and force control concept for coping with the industry requirement of introducing more automation in the finishing of surfaces. Such a control concept allows on one hand the finishing of moving parts and at the same time increases the flexibility of the programming and reduces the user effort.

Details

Industrial Robot: An International Journal, vol. 35 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 1 February 1994

Jurgen Schmidt and Uwe Schauer

Describes a project to develop an intelligent robot system to mechanizethe finishing of dies and moulds. Examines the concept of the finishing ofsurfaces and the…

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163

Abstract

Describes a project to develop an intelligent robot system to mechanize the finishing of dies and moulds. Examines the concept of the finishing of surfaces and the distinction between grinding and polishing.

Details

Industrial Robot: An International Journal, vol. 21 no. 1
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 19 October 2015

Alberto Boschetto and Luana Bottini

The purpose of this paper is to study the integration between this technology and barrel finishing (BF) operation to improve part surface quality. Fused deposition…

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1310

Abstract

Purpose

The purpose of this paper is to study the integration between this technology and barrel finishing (BF) operation to improve part surface quality. Fused deposition modeling (FDM) processes have limitation in term of accuracy and surface finishing. Hence, post-processing operations are needed. A theoretical and experimental investigations have been carried out.

Design/methodology/approach

A geometrical model of the profile under the action of machining is proposed. The model takes into account FDM formulation and allows to predict the surface morphology achievable by BF. The MR needed in the model is obtained by a particular profilometer methodology, based on the alignment of Firestone–Abbot (F–A) curves. The experimental performed on a suitable geometry validated geometrical model. Profilometer and dimensional measurements have been used to assess the output of the coupled technologies in terms of surface roughness and accuracy.

Findings

The coupling of FDM and BF has been assessed and characterized in terms of obtained part surfaces and dimension evolution. Deposition angle strongly affects the BF removal speed and alters nominal dimensions of part. The geometric profile model gave interesting information about profile morphology and machining mechanism; moreover, the height prevision allows to estimate BF working time to accomplish part requirements.

Research limitations/implications

The prediction of the geometric profile as a function of FDM fabrication parameters is a powerful tool which permits to investigate surface properties such as mechanical coupling or tribological aspects. The coupling of BF and FDM has been assessed and now optimization of this process can be performed just evaluating effects of parameters.

Practical implications

This research has been focused to an industrial application, and results can be used in a computer-aided manufacturing. The prevision of surface obtainable by this integration is a tool to find the part optimum orientation to accomplish the drawing requirements. Both the experimental findings and the model can guide operator toward a proper process improvement, thus reducing or eliminating expensive trial and error phase in the post-processing operation of FDM prototypes.

Originality/value

In this paper, a novel model has been presented. It allows to know in advance profile morphology achievable by a specific surface of a FDM part after a determined BF working time. A particular application of FA curves gives the MR values.

Details

Rapid Prototyping Journal, vol. 21 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 13 November 2017

Wilian da Silva Labiapari, Henara Lillian Costa and José Daniel Biasoli De Mello

The progressive wear of cutting tools used in industrial cutlery production results in excessive burr formation and reduces tool service life. This paper aims to…

Abstract

Purpose

The progressive wear of cutting tools used in industrial cutlery production results in excessive burr formation and reduces tool service life. This paper aims to investigate the effects of the sheet surface finish on tool wear and service life during blanking.

Design/methodology/approach

Two alternative surface finish techniques were proposed and initially implemented under laboratorial conditions and compared with conventional acid pickling. Those surface finish techniques were then implemented on an industrial scale to improve the service life of cutting tools. Industrial blanking tests characterized the effect of sheet surface finish on tool life.

Findings

In the first technique, called skin pass, an additional mechanical pass under controlled conditions reduced the height of the surface peaks and resulted in partial embedding of the carbides into the surface. The second technique, called electrochemical pickling, removed solely the surface carbides, leaving behind a smoother surface without carbides. Real industrial blanking tests identified that the use of skin pass reduced burr formation and increased tool life by around 300 per cent when compared with conventional acid pickling. With electrochemical pickling, burr formation was further reduced and tool life increased further by 300 per cent when compared with skin pass.

Research limitations/implications

First, this work proposes an alternative surface finishing technique (electrochemical pickling) to be used after annealing of stainless steel. Second, the work clearly shows the presence of protruding surface carbides when conventional surface finishing techniques are used, which do not exist after acid pickling.

Practical implications

When electrochemical pickling is implemented on an industrial scale, the life of blanking tools is substantially improved.

Originality/value

Although the sheet surface finish is widely recognized to affect metalforming processes, the literature lacks studies on the effect of sheet surface finish on tool wear during blanking. First, this work proposes an alternative surface finishing technique (electrochemical pickling) to be used after annealing of stainless steel. Second, the work clearly shows the presence of protruding surface carbides when conventional surface finishing techniques are used, which do not exist after acid pickling. Third, when electrochemical pickling is implemented on an industrial scale, the life of blanking tools is substantially improved.

Details

Industrial Lubrication and Tribology, vol. 69 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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