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Article
Publication date: 10 June 2014

Syed Hammad Mian, Mohammed Abdul Mannan and Abdulrahman M. Al-Ahmari

The purpose of this paper is to investigate the influence of surface topology on the performance of laser line scanning probe and to suggest methodology for 3D…

Abstract

Purpose

The purpose of this paper is to investigate the influence of surface topology on the performance of laser line scanning probe and to suggest methodology for 3D digitization of specular surfaces.

Design/methodology/approach

Two different molds, one having milled surface and the other with polished surface, were used to identify effect of surface characteristics on the performance of laser line scanning probe mounted on bridge-type coordinate measuring machine. The point cloud data acquisition of two surfaces was carried out using different combinations of laser scanning parameters. The point cloud sets thus obtained were analyzed in terms of completeness, noise and accuracy. The polished mold which exhibited specular reflection was digitized at different scanning angles of laser line scanning probe using the best combination of scanning parameters.

Findings

Results confirmed that surface characteristics play important role to determine quality of the reverse engineering (RE) process. The results in terms of completeness, accuracy and noise for point cloud sets have successfully been obtained for milled and polished surfaces. Three-dimensional (3D) comparison analysis suggested larger deviation in cases of polished surface as compared to milled surface. The point cloud set acquired with proposed approach was better in terms of both completeness and noise reduction.

Originality/value

There has been an increased demand for measurement of metallic, polished and shiny surfaces in automotive, aerospace and medical industries. These surfaces are very difficult to scan because they exhibit specular reflection instead of diffuse reflection. Laser line scanning probe which is a non-contact method is in great demand for RE. This is due to the fact that it possesses very high data acquisition speed. However, laser scanning is hugely affected by surface characteristics which in turn govern specular reflection.In this paper, it has been shown that a surface that exhibits various degrees of specular reflection can be digitized efficiently if appropriate combination of scanning parameters and positions of laser line scanning probe are used. Also, this paper has attempted to offer a procedure to overcome incompleteness and noise in 3D data as obtained by the laser line scanning probe.

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Article
Publication date: 17 October 2017

Changhui Song, Aibing Huang, Yongqiang Yang, Zefeng Xiao and Jia-kuo Yu

This study aims to achieve customized prosthesis for total joint arthroplasty and total hip arthroplasty. Selective laser sintering (SLS) as additive manufacturing could…

Abstract

Purpose

This study aims to achieve customized prosthesis for total joint arthroplasty and total hip arthroplasty. Selective laser sintering (SLS) as additive manufacturing could enable small-scale fabrication of customized Ultra High Molecular Weight Polyethylene (UHMWPE) components; however, the processes for SLS of UHMWPE need to be improved.

Design/methodology/approach

This paper begins by improving the preheating system of the SLS fabricating equipment and then fabricating cuboids with the same size and cuboids with same volume and different size to study the warpage, demonstrating the effect of the value and uniformity of the preheating temperature on component fabrication. Warpage, density and tensile properties are investigated from the perspective of energy input density. Finally, complicated industrial parts are produced effectively by using optimized technological parameters.

Findings

The results show that components can be fabricated effectively after the optimization of the SLS technological parameters i.e. the preheating temperature the laser power the scanning interval and the scanning speed. The resulting warpage was found to be less than 0.1 mm along with the density as 83.25 and the tensile strength up to 14.1 Mpa. UHMWPE sample parts with good appearance and strength are obtained after ascertaining the effect of each factor on the fabrication of the sample parts.

Originality/value

It is very challenging to fabricate UHMWPE sample parts by SLS. This is a new step in the fabrication of customized UHMWPE sample parts.

Details

Rapid Prototyping Journal, vol. 23 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 2002

K. Dai and L. Shaw

Residual thermal stresses and distortion are frequently present in the parts built using a layer‐by‐layer solid freeform fabrication techniques assisted with a moving laser

Abstract

Residual thermal stresses and distortion are frequently present in the parts built using a layer‐by‐layer solid freeform fabrication techniques assisted with a moving laser source. This study uses finite element analysis to investigate the effect of laser scanning patterns on residual thermal stresses and distortion. It is shown that the out‐of‐plane distortion of a layer, processed by a moving laser beam can be minimized with a proper selection of the laser scanning pattern. A scanning pattern having changes in its scanning direction frequently by 90° at every turn can lead to the cancellation of concave upward and downward distortions. As a result of this cancellation, very small distortion is present in the laser processed plate. It is also found that distortion is mainly caused by transient thermal stresses rather than residual thermal stresses.

Details

Rapid Prototyping Journal, vol. 8 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 25 June 2020

Yang Tian, Dacian Tomus, Aijun Huang and Xinhua Wu

Limited research has attempted to reveal the different modes of the melt pool formation in additive manufacturing. This paper aims to study the mechanisms of surface…

Abstract

Purpose

Limited research has attempted to reveal the different modes of the melt pool formation in additive manufacturing. This paper aims to study the mechanisms of surface roughness formation, especially on the aspect of melt pool formation which determine the surface profile and consequently significantly influence the surface roughness.

Design/methodology/approach

In this study, the conditions under which different modes of melt pool formation (conduction mode and keyhole mode) occur for the case of as-fabricated Hastelloy X using direct metal laser solidification (DMLS) are derived and validated experimentally. Top surfaces of uni-directionally built samples under various processing conditions are cut, grinded, polished and etched to reveal their individual melt pool morphologies. Similarly, up-skin (slope angle < 90°) and down-skin (slope angle > 90°) melt pool morphologies are also investigated to compare the differences. Surface tension gradients and resultant Marangoni flow, which dominate the melt flow in the melt pool, is also calculated to help better evaluate the melt pool shape forming.

Findings

Two types of melt pool formation modes are dominating in DMLS: conduction mode and keyhole mode. Melt pool formed by conduction mode generally has an aspect ratio of 1:2 (depth vs width) and is in elliptical shape. Appropriate selection of scanning laser power and speed are required to maintain a low characteristic length and width ratio to prevent ballings. Melt pool formed by keyhole mode has an aspect ratio of 1:1 or less. High-energy contour promotes formation of key-hole-shaped melt pool which fills the gaps between layers and smoothens the up-skin surface roughness. Low-energy contour scan is necessary for down-skin surface to form small melt pool profiles and achieve low Ra.

Originality/value

This paper provides valuable insight into the origins of surface quality problem of DMLS, which is a very critical issue for upgrading the process for manufacturing real components. This paper helps promote the understanding of the attributes and capabilities of this rapidly evolving three-dimensional printing technology and allow appropriate control of processing parameters for successful fabrication of components with sound surface quality.

Details

Rapid Prototyping Journal, vol. 26 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 30 January 2020

Shugong Wei

In this paper, an experimental apparatus was designed and subsequent theoretical analysis and simulations were conducted on the effectiveness and advantages of a novel…

Abstract

Purpose

In this paper, an experimental apparatus was designed and subsequent theoretical analysis and simulations were conducted on the effectiveness and advantages of a novel laser beam scan localization (BLS) system.

Design/methodology/approach

The system used a moving location assistant (LA) with a laser beam, through which the deployed area was scanned. The laser beam sent identity documents (IDs) to unknown nodes to obtain the sensor locations.

Findings

The results showed that the system yielded significant benefits compared with other localization methods, and a high localization accuracy could be achieved without the aid of expensive hardware on the sensor nodes. Furthermore, four positioning mode features in this localization system were realized and compared.

Originality/value

In this paper, an experimental apparatus was designed and subsequent theoretical analysis and simulations were conducted on the effectiveness and advantages of a novel laser BLS system. The system used a moving LA with a laser beam, through which the deployed area was scanned. The laser beam sent IDs to unknown nodes to obtain the sensor locations.

Details

Sensor Review, vol. 40 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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Article
Publication date: 13 July 2017

Erika Anneli Pärn and David Edwards

The purpose of this paper is to present a literature review of laser scanning and 3D modelling devices, modes of delivery and applications within the architecture…

Abstract

Purpose

The purpose of this paper is to present a literature review of laser scanning and 3D modelling devices, modes of delivery and applications within the architecture, engineering, construction and owner-operated sector. Such devices are inextricably linked to modern digital built environment practices, particularly when used in conjunction with as-built building information modelling (BIM) development. The research also reports upon innovative technological advancements (such as machine vision) that coalesce with 3D scanning solutions.

Design/methodology/approach

A synthesis of literature is used to develop: a hierarchy of the modes of delivery for laser scan devices; a thematic analysis of 3D terrestrial laser scan technology applications; and a componential cross-comparative tabulation of laser scan technology and specifications.

Findings

Findings reveal that the costly and labour intensive attributes of laser scanning devices have stimulated the development of hybrid automated and intelligent technologies to improve performance. Such developments are set to satisfy the increasing demand for digitisation of both existing and new buildings into BIM. Future work proposed will seek to: review what coalescence of digital technologies will provide an optimal and cost-effective solution to accurately re-constructing the digital built environment; conduct case studies that implement hybrid digital solutions in pragmatic facilities management scenarios to measure their performance and user satisfaction; and eliminate manual remodelling tasks (such as point cloud reconstruction) via the use of computational intelligence algorithms integral within cloud-based BIM platforms.

Originality/value

Although laser scanning and 3D modelling have been widely covered en passant within the literature, scant research has conducted a holistic review of the technology, its applications and future developments. This review presents concise and lucid reference guidance that will intellectually challenge, and better inform, both practitioners and researchers.

Details

Built Environment Project and Asset Management, vol. 7 no. 3
Type: Research Article
ISSN: 2044-124X

Keywords

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Article
Publication date: 28 September 2012

Yongqiang Yang, Jian‐bin Lu, Zhi‐Yi Luo and Di Wang

The purpose of this paper is to investigate the research approach to optimize shape accuracy, dimensional accuracy and density of customized orthodontic production…

Abstract

Purpose

The purpose of this paper is to investigate the research approach to optimize shape accuracy, dimensional accuracy and density of customized orthodontic production fabricated by selective laser melting (SLM).

Design/methodology/approach

A series of process experiments were applied to fabricating customized brackets directly by SLM, using 316L stainless steel. Shape accuracy can be optimized through the study on fabricating characteristics of non‐support overhanging structure. A scanning strategy combining contour scanning with orthogonal scanning, which differ in scanning speed and spot compensations, was proposed to improve dimensional accuracy. Scanning laser surface re‐melting was added to enhance the SLM density.

Findings

Optimized SLM parameters lead to high shape precision of customized brackets, and the average size error of bracket slot is less than 10 μm. The customized brackets density is more than 99 per cent, and the surface quality and mechanical properties meet the requirements.

Originality/value

The paper presents the state of the art in SLM of customized production (especially medical appliances) by optimizing part properties. It is the first time that SLM is employed in the manufacturing of customized orthodontic products. It shows the original research on overhanging structure and compound scanning strategy, approach to optimize SLM part accuracy. An improved laser surface re‐melting is employed in the density optimization.

Details

Rapid Prototyping Journal, vol. 18 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 26 October 2012

O. Momin, S.Z. Shuja and B.S. Yilbas

A model study of laser heating process including phase change and molten flow in the melt pool gives physical insight into the process and provides useful information on…

Abstract

Purpose

A model study of laser heating process including phase change and molten flow in the melt pool gives physical insight into the process and provides useful information on the influence of melting parameters. In addition, the predictions reduce the experimental cost and minimize the experimental time. Consequently, investigation into laser control melting of the titanium alloy becomes essential. The purpose of this paper is to do this.

Design/methodology/approach

Laser repetitive pulse heating of titanium surface is investigated and temperature field as well as Marangoni flow in the melt pool is predicted using finite volume approach. The influence of laser scanning speed and laser pulse parameter (defining the laser pulse intensity distribution at the workpiece surface) on temperature distribution and melt size is examined. The experiment is carried out to validate temperature predictions for two consecutive laser pulses.

Findings

The influence of laser scanning speed is significant on the melt pool geometry, which is more pronounced for the laser pulse parameter β=0. Temperature predictions agree with the thermocouple data obtained from the experiment.

Research limitations/implications

Although temperature dependent properties are used in the simulations, isotropy in properties may limit the simulations. The laser canning speed is limited to 0.3 m/s, which is good for surface treatment process, but it may slow for annealing treatments.

Practical implications

The results are very useful to capture insight into the melting process. In addition, the influence of laser scanning speed and laser pulse intensity distribution on the melt formation in the surface vicinity is well presented, which will be useful for those working on laser surface treatment process.

Originality/value

The work is original and findings are new, which demonstrate the influence of laser parameters on the melt pool formation and resulting Marangoni flow.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 29 March 2021

Kamel Ettaieb, Sylvain Lavernhe and Christophe Tournier

This paper aims to propose an analytical thermal three-dimensional model that allows an efficient evaluation of the thermal effect of the laser-scanning path. During…

Abstract

Purpose

This paper aims to propose an analytical thermal three-dimensional model that allows an efficient evaluation of the thermal effect of the laser-scanning path. During manufacturing by laser powder bed fusion (LPBF), the laser-scanning path influences the thermo-mechanical behavior of parts. Therefore, it is necessary to validate the path generation considering the thermal behavior induced by this process to improve the quality of parts.

Design/methodology/approach

The proposed model, based on the effect of successive thermal flashes along the scanning path, is calibrated and validated by comparison with thermal results obtained by FEM software and experimental measurements. A numerical investigation is performed to compare different scanning path strategies on the Ti6Al4V material with different stimulation parameters.

Findings

The simulation results confirm the effectiveness of the approach to simulate the thermal field to validate the scanning strategy. It suggests a change in the scale of simulation thanks to high-performance computing resources.

Originality/value

The flash-based approach is designed to ensure the quality of the simulated thermal field while minimizing the computational cost.

Details

Rapid Prototyping Journal, vol. 27 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 12 April 2018

Abdul Fatah Firdaus Abu Hanipah and Khairul Nizam Tahar

Laser scanning technique is used to measure and model objects using point cloud data generated laser pulses. Conventional techniques to construct 3D models are time…

Abstract

Purpose

Laser scanning technique is used to measure and model objects using point cloud data generated laser pulses. Conventional techniques to construct 3D models are time consuming, costly and need more manpower. The purpose of this paper is to assess the 3D model of the Sultan Salahuddin Abdul Aziz Shah Mosque’s main dome using a terrestrial laser scanner.

Design/methodology/approach

A laser scanner works through line of sight, which indicates that multiple scans need to be taken from a different view to ensure a complete data set. Targets must spread in all directions, and targets should be placed on fixed structures and flat surfaces for the normal scan and fine scan. After the scanning operation, point cloud data from the laser scanner were cleaned and registered before a 3D model could be developed.

Findings

As a result, the reconstruction of the 3D model was successfully developed. The samples are based on the triangle dimension, curve line, horizontal dimension and vertical dimension at the dome. The standard deviation and accuracy are calculated based on the comparison of the 21 samples taken between the high-resolution and low-resolution scanning data.

Originality/value

There are many ways to develop the 3D model and based on this study, the less complex ways also produce the best result. The authors implement the different types of dimensions for the 3D model assessment, which have not yet been considered in the past.

Details

International Journal of Building Pathology and Adaptation, vol. 36 no. 2
Type: Research Article
ISSN: 2398-4708

Keywords

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