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Article
Publication date: 1 July 2005

X. Li, J. Wang and L.L. Shaw

To investigate the effect of laser densification parameters on the cross section geometry of the laser‐densified single line, and thus provide guidance for selecting the laser…

Abstract

Purpose

To investigate the effect of laser densification parameters on the cross section geometry of the laser‐densified single line, and thus provide guidance for selecting the laser processing condition to obtain dense shapes with minimum processing defects.

Design/methodology/approach

A range of dental porcelain powder lines with small cross section areas (in the order of 1 × 1 mm2) were extruded from micro‐extruders and laser densified with the systematically changed peak laser power intensity, laser beam diameter, and ratio of the laser beam diameter to the width of the powder line.

Findings

The peak laser power intensity, laser beam diameter, and ratio of the laser beam diameter to the width of the powder line have substantial influence on the cross section geometry. The effects of these laser processing parameters can be explained in terms of minimization of surface energy in both solid and liquid states, volume shrinkage associated with densification, and temperature gradients present in the powder line during laser densification.

Originality/value

For the first time the cross section geometry of single powder lines in response to laser processing conditions has been systematically investigated, and the result offers guidance for obtaining dense shapes with minimum processing defects.

Details

Rapid Prototyping Journal, vol. 11 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 4 January 2021

Andrea Rocio Urbina

This study aims to question the fact that density has been considered only as an instrument of calculation to be used on regulation mechanisms, without taking into consideration…

Abstract

Purpose

This study aims to question the fact that density has been considered only as an instrument of calculation to be used on regulation mechanisms, without taking into consideration other variables related to density. The paper proposes a framework consisting of four determining factors for urban analysis that have to be considered before starting a densification process: connectivity and permeability of network, mixture of uses, relation to urban morphology and public spaces for each district. The methodological analysis was carried out for the case of the district of Gruta de Lourdes, Quinta Normal, located in northwest Santiago, which has started a densification process the recent years.

Design/methodology/approach

The present discussion aims to obtain objective parameters to determine if urban development allows livability and a balanced relationship with actual urban form and diversity. There appear to be four determining factors of urban analysis: connectivity and network permeability, the mixture of uses, public spaces and urban form development. The district of Gruta de Lourdes will be used to delve into these parameters to place the debate around density in objective terms. To look in depth at each of the criteria for evaluating densification processes, various methods were selected for quantifying the observed variables: to evaluate connectivity and integration of a neighborhood with the rest of the city, the spatial configuration analysis “Space Syntax” will be used; to evaluate mix of uses, mixed-use index, or ratio of non-residential use will be used; urban morphology, plot size, housing density (dw/ha), lot coverage and floor area ratio will be used; public spaces, the percentage dedicated to each of these in m2/inhab.

Findings

The results allow us to conclude that it is necessary to plan densification processes via an analysis that promotes connectivity, mixture of uses, urban morphology and the available public spaces to understand density as a multivariable phenomenon. In addition, we conclude that the case study district, Gruta de Lourdes, can withstand greater demand for housing as long as the context is taken into account. A possible option to asset the densification potential could be the “infill” strategy, which aims to be a type of intervention that does not change the structure of the neighborhood as new buildings are positioned among existing ones, maintaining the form of the streets and the structure of plot divisions.

Originality/value

The value of the paper is to contribute to the discussion on how to renovate central areas in Latin American cities looking at variables such as connectivity, mixture of uses, urban morphology and public spaces, which are directly related to density. Moreover, the paper contributes to discuss new ways to analyze and measure densification, toward planning a district’s renovation. In addition, the quantitative methodological approach to the densification processes gives a new understanding of how to determine density. Finally, the paper reveals an opportunity to rethink the inner city toward new approaches to renovation developments.

Article
Publication date: 1 February 2005

Xiaoxuan Li, Jiwen Wang, Leon L. Shaw and Thomas B. Cameron

Commercial dental porcelain powder was deposited via slurry extrusion and laser densified to fabricate dental restorations in a multi‐material laser densification (MMLD) process.

1982

Abstract

Purpose

Commercial dental porcelain powder was deposited via slurry extrusion and laser densified to fabricate dental restorations in a multi‐material laser densification (MMLD) process.

Design/methodology/approach

A dental porcelain slurry was made from ball milled dental porcelain powders and extruded using the MMLD system. Extruded lines and rings were laser densified under different conditions in order to study how to build fully dense porcelain layers without warping and cracking during the MMLD process.

Findings

The geometric cross section of laser densified porcelain lines were dependent on laser processing parameters. Laser densified single ring showed no warping, and multiple layer body after laser densification showed cracks in the rings. The interface microstructure suggested good bonding between multiple layers. The mechanism to achieve single porcelain ring without warping and cracking is discussed. Alternate ways to build physical tooth layer by layer are proposed.

Originality/value

In the MMLD process, dental porcelain slurry was extruded from a human tooth computer file and laser densified to manufacture dental restorations based on solid freeform fabrication (SFF) principles. The understanding developed will pave the way for fabricating a physical dental restoration unit in the near future.

Details

Rapid Prototyping Journal, vol. 11 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 11 January 2022

Anja Jørgensen and Mia Arp Fallov

There is a growing importance for public facilitation of corporate social responsibility and involvement of civil organizations in securing territorial cohesion and development…

Abstract

Purpose

There is a growing importance for public facilitation of corporate social responsibility and involvement of civil organizations in securing territorial cohesion and development. In the present article, the authors focus on how we are to understand a locally sensitive organization of territorial cohesion in the Danish context. Traditional sociological concepts and standardized area-types used for administrative purposes have turned out not being very helpful in understanding the interrelation between inequality, urbanization and territorial cohesion. The authors argue for a processual and relational approach to urbanization.

Design/methodology/approach

The present article is based on interview material and policy documents from three Danish case studies representing urban, suburban and rural forms of settlement. The case studies are part of a cross-European research project.

Findings

The authors show how territorial governance play a key role in the strategies of densification/de-densification facilitating shielding capacities of collective efficacy, and reversely that bottom-up innovations are crucial for the ability of territorial governance to mobilize territorial capital and mediate in effects of territorial inequality. Spatial imaginaries legitimize these efforts to organize cohesion. The spatial imaginaries work as common frame of references for the interplay between strategies of (de)densification and collective efficacy, and they activate particular balances between growth agendas and everyday life.

Originality/value

These findings represent an original perspective on how and why urbanization impact on places in a more specific and variated way than often portrayed as it highlight how social capacities tied to place might work with or against existing social, economic and cultural structures shaping territorial cohesion.

Details

Journal of Organizational Ethnography, vol. 11 no. 1
Type: Research Article
ISSN: 2046-6749

Keywords

Book part
Publication date: 24 May 2012

Dominique Bessire and Emmanuelle Mazuyer

Corporate social responsibility (CSR) is an emerging field whose norms are still being written and rewritten. The concept of CSR as we know it today1 started in the United States…

Abstract

Corporate social responsibility (CSR) is an emerging field whose norms are still being written and rewritten. The concept of CSR as we know it today1 started in the United States in the 1970s and 1980s and slowly spread to other developed countries in the 1980s and 1990s. The French for corporate social responsibility is Responsabilité sociale de l'entreprise (RSE), a nearly literal translation which however diverges to some extent from the original English. The concept is still unclear despite having been the subject of an increasing number of academic and professional papers, in management as well as in law journals. In the present study, we shall use the definition as set by the European Commission (2001), which defines it as ‘a concept whereby companies integrate social and environmental concerns in their business operations and in their interaction with their stakeholders on a voluntary basis’. The European Commission in its Communication to the Parliament (2006) has stressed the fact that ‘it is about enterprises deciding to go beyond minimum legal requirements and obligations (our emphasis) stemming from collective agreements in order to address societal needs’. The second part of the definition is often omitted, but is at the crux of the problem of determining where CSR begins and ends. Corporate practices which involve ethical, social or environmental problems are defined as CSR practices only if companies go above and beyond their legal obligations. It should also be noted that the definition does not specify which guidelines to take into account in order to identify the standards to be applied in any given circumstances.

Details

Business Strategy and Sustainability
Type: Book
ISBN: 978-1-78052-737-6

Article
Publication date: 29 April 2014

R.X. Cheng

This paper developed a new method of making floor from poplar using glued technology and densification technology. This paper aimed to use fast-grown poplar wood to produce floor…

Abstract

Purpose

This paper developed a new method of making floor from poplar using glued technology and densification technology. This paper aimed to use fast-grown poplar wood to produce floor to expand material supply range of floor in order to solve problem of material supply shortage for floor industry.

Design/methodology/approach

Densification technology and gluing technology were used to obtain high-density surface materials of floor under high pressure, meanwhile in order to reduce loss of poplar wood caused by compressing, high-density surface materials floor and substrate are glued and pressed under low pressure.

Findings

The method of compressing poplar wood under high pressure can improve poplar's physical and mechanical properties. Adopting densification technology and gluing technology can produce the poplar laminated composite floor which meets the requirements of Chinese standard GB/T 18103.

Research limitations/implications

This method of producing floor by compression densification technology would cause wood loss from reduction in thickness because poplar was pressed under high pressure.

Practical implications

This method of making floor from poplar wood concerned in this study allows the floor making industry to eliminate its dependence on precious wood resource, expand supply range of floor material, and then solve problem of wood supply shortage of floor industry.

Originality/value

This study may help solve the difficult problem that poplar cannot directly be used to produce floor because of its softness, low density and low strength. Through densification technology, great improvement in strength and hardness of poplar had been made.

Details

Pigment & Resin Technology, vol. 43 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 25 January 2022

Tobia Romano, Emanuele Migliori, Marco Mariani, Nora Lecis and Maurizio Vedani

Binder jetting is a promising route to produce complex copper components for electronic/thermal applications. This paper aims to lay a framework for determining the effects of…

Abstract

Purpose

Binder jetting is a promising route to produce complex copper components for electronic/thermal applications. This paper aims to lay a framework for determining the effects of sintering parameters on the final microstructure of copper parts fabricated through binder jetting.

Design/methodology/approach

The knowledge gained from well-established powder metallurgy processes was leveraged to study the densification behaviour of a fine high-purity copper powder (D50 of 3.4 µm) processed via binder jetting, by performing dilatometry and microstructural characterization. The effects of sintering parameters on densification of samples obtained with a commercial water-based binder were also explored.

Findings

Sintering started at lower temperature in cold-pressed (∼680 °C) than in binder jetted parts (∼900 °C), because the strain energy introduced by powder compression reduces the sintering activation energy. Vacuum sintering promoted pore closure, resulting in greater and more uniform densification than sintering in argon, as argon pressure stabilizes the residual porosity. About 6.9% residual porosity was obtained with air sintering in the presence of graphite, promoting solid-state diffusion by copper oxide reduction.

Originality/value

This paper reports the first systematic characterization of the thermal events occurring during solid-state sintering of high-purity copper under different atmospheres. The results can be used to optimize the sintering parameters for the manufacturing of complex copper components through binder jetting.

Details

Rapid Prototyping Journal, vol. 28 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 16 November 2018

Robert Fleischhauer, Jens U. Hartig, Peer Haller and Michael Kaliske

The purpose of this study is the numerical investigation of densification and molding processes of wood. Providing theoretical and numerical approaches with respect to a…

Abstract

Purpose

The purpose of this study is the numerical investigation of densification and molding processes of wood. Providing theoretical and numerical approaches with respect to a consistent multi-physical finite element method framework are further goals of this research.

Design/methodology/approach

Constitutive phenomenological descriptions of the thermo-mechanical and moisture-dependent material characteristics of wood are introduced. Special focus is given to a consistent hygro-thermo-mechanical modeling at finite deformations to capture the realistic material behavior of wood, especially when it is subjected to densification and molding processes.

Findings

Realistic theoretical formulations of different hygro-thermo-mechanical processes are provided. A successful numerical modeling is demonstrated for beech wood by validation at experimental findings.

Originality/value

The constitutive laws and numerical findings are new, as they govern a multi-physical large deformation framework and are applied to the advanced technology of densification and molding of wood.

Details

Engineering Computations, vol. 36 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 6 November 2017

Seishiro Matsubara, Kenjiro Tarada, Takaya Kobayashi, Toshiyuki Saitou, Manabu Umeda, Yasuko Mihara, Kai Oide, Hiroto Shin and Yasuhiro Katsuda

The purpose of this paper is to propose a set of constitutive functions for dried bodies for accurate prediction of the entire deformation process of ceramic products during…

Abstract

Purpose

The purpose of this paper is to propose a set of constitutive functions for dried bodies for accurate prediction of the entire deformation process of ceramic products during firing and to present relevant methods for determining their coefficients from a series of respective thermo-mechanical analysis (TMA) tests.

Design/methodology/approach

The function forms of the sintering-induced strain rate, viscoplastic multiplier and elastic modulus are formulated in order with reference to empirical data of relative densities. Separate TMA tests are conducted to identify their coefficients, while a stairway thermal cycle test is carried out to identify the parameters in the densification rate. Then, various finite element analyses (FEA) are performed for accuracy confirmation.

Findings

The performances of the present constitutive functions along with the identified material parameters were validated in comparison with the relevant test results. It has then been confirmed that these functions enable us to some extent to accurately estimate the non-mechanical and mechanical deformations of dried bodies during firing. Also, by performing FEA of an actual sanitary ware product, the applicability and capability of the proposed set of constitutive functions could be demonstrated.

Practical implications

The present methodology with the proposed constitutive functions is a simple, but reliable and practical approach for simulating the deformation process of arbitrary ceramic products subjected to firing and applicable for practical applications in various engineering fields.

Originality/value

The constitutive functions of the viscoplastic multiplier and elastic modulus, which enable us to properly characterize the mechanical behavior of dried bodies subjected to firing, are originally formulated in analogy with that of the sintering-induced strain.

Details

Engineering Computations, vol. 34 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 11 January 2013

Haihong Zhu, Linda Ke, Wenjuan Lei, Cheng Dai and Baijin Chen

The purpose of this paper is to investigate the effect of the Q‐switching parameters on the sintering behavior of laser micro sintering Cu‐based metal powder, using Q‐switched…

Abstract

Purpose

The purpose of this paper is to investigate the effect of the Q‐switching parameters on the sintering behavior of laser micro sintering Cu‐based metal powder, using Q‐switched 1064 nm Nd‐YAG laser.

Design/methodology/approach

An experimental study has been performed. Metal powder mixture with Cu and Cu‐P alloy powders has been utilized. Q‐switching duration of 15 μs∼25 μs, rate of 25 kHz∼45 kHz have been used.

Findings

The results show that as the Q‐switching rate and duration increases, the peak laser power decreases and the densification enhances. However, an optimal peak laser power exists and if the peak laser power is too low, the density of the sample is also low. The densification regime of laser micro‐sintering is not only caused by the liquid phase filling the pores, but is also caused by the Cu powder migrating and by coalescence, e.g. including initial stage and intermediate stage of the traditional furnace liquid phase sintering. However, the degree of these stages depends on the peak power and input laser energy.

Originality/value

The effect of the Q‐switching parameters on sintering behavior of laser micro sintering Cu‐based metal powder using Q‐switched 1064 nm Nd‐YAG laser has been obtained. It is found that the densification behavior is Q‐switching parameters dependent, although the average laser power is same. The densification regime of laser micro‐sintering includes initial stage and intermediate stage of the traditional furnace liquid phase sintering, but the degree is Q‐switching parameters dependent.

Details

Rapid Prototyping Journal, vol. 19 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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