Search results

1 – 10 of 84
To view the access options for this content please click here
Article
Publication date: 18 April 2016

Jan Patrick Deckers, Khuram Shahzad, Ludwig Cardon, Marleen Rombouts, Jozef Vleugels and Jean-Pierre Kruth

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential…

Abstract

Purpose

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential to rapidly shape ceramic parts with an almost unlimited shape freedom. In this paper, alumina (Al2O3) parts are produced, as Al2O3 is currently the most commonly used ceramic material for technical applications.

Design/methodology/approach

Variants of the following PM route, with indirect selective laser sintering (indirect SLS) as the AM shaping step, are explored to produce ceramic parts: powder synthesis, indirect SLS, binder removal and furnace sintering and alternative densification steps.

Findings

Freeform-shaped Al2O3 parts with densities up to approximately 90 per cent are obtained.

Research limitations/implications

The resulting Al2O3 parts contain inter-agglomerate pores. To produce higher-quality ceramic parts through indirect SLS, these pores should be avoided or eliminated.

Originality/value

The research is innovative in many ways. First, composite powders are produced using different powder production methods, such as temperature-induced phase separation and dispersion polymerization. Second, four different binder materials are investigated: polyamide (nylon-12), polystyrene, polypropylene and a carnauba wax – low-density polyethylene combination. Further, to produce ceramic parts with increased density, the following densification techniques are investigated as additional steps of the PM process: laser remelting, isostatic pressing and infiltration.

Details

Rapid Prototyping Journal, vol. 22 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article
Publication date: 2 August 2011

Evren Yasa, Jan Deckers and Jean‐Pierre Kruth

Selective laser melting (SLM) is a powder metallurgical (PM) additive manufacturing process whereby a three‐dimensional part is built in a layer‐wise manner. During the…

Abstract

Purpose

Selective laser melting (SLM) is a powder metallurgical (PM) additive manufacturing process whereby a three‐dimensional part is built in a layer‐wise manner. During the process, a high intensity laser beam selectively scans a powder bed according to the computer‐aided design data of the part to be produced and the powder metal particles are completely molten. The process is capable of producing near full density (∼98‐99 per cent relative density) and functional metallic parts with a high geometrical freedom. However, insufficient surface quality of produced parts is one of the important limitations of the process. The purpose of this study is to apply laser re‐melting using a continuous wave laser during SLM production of 316L stainless steel and Ti6Al4V parts to overcome this limitation.

Design/methodology/approach

After each layer is fully molten, the same slice data are used to re‐expose the layer for laser re‐melting. In this manner, laser re‐melting does not only improve the surface quality on the top surfaces, but also has the potential to change the microstructure and to improve the obtained density. The influence of laser re‐melting on the surface quality, density and microstructure is studied varying the operating parameters for re‐melting such as scan speed, laser power and scan spacing.

Findings

It is concluded that laser re‐melting is a promising method to enhance the density and surface quality of SLM parts at a cost of longer production times. Laser re‐melting improves the density to almost 100 per cent whereas 90 per cent enhancement is achieved in the surface quality of SLM parts after laser re‐melting. The microhardness is improved in the laser re‐molten zone if sufficiently high‐energy densities are provided, probably due to a fine‐cell size encountered in the microstructure.

Originality/value

There has been extensive research in the field of laser surface modification techniques, e.g. laser polishing, laser hardening and laser surface melting, applied to bulk materials produced by conventional manufacturing processes. However, those studies only relate to laser enhancement of surface or sub‐surface properties of parts produced using bulk material. They do not aim at enhancement of core material properties, nor surface enhancement of (rough) surfaces produced in a PM way by SLM. This study is carried out to cover the gap and analyze the advantages of laser re‐melting in the field of additive manufacturing.

Details

Rapid Prototyping Journal, vol. 17 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article
Publication date: 27 July 2012

J. Deckers, K. Shahzad, J. Vleugels and J.P. Kruth

The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect selective laser sintering (SLS). Density measurements, some…

Abstract

Purpose

The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect selective laser sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.

Design/methodology/approach

The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and sintering (FS) stages of the powder metallurgy process were sequentially investigated.

Findings

Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different kinds of pore morphologies, i.e. long elongated pores, which stem from the intergranular spacings during SLS, and intermediate pores, which likely originate from larger polyamide agglomerates in the ball milled powder. Also, QIPing at elevated temperatures is found to be a promising alternative for CIPing at room temperature to increase the final part density.

Research limitations/implications

Cracks, long elongated pores and intermediate pores remained in the sintered parts. Homogenizing the microstructure of the parts through optimizing the composite starting powder, the deposition during SLS, the SLS parameters and QIPing parameters is essential to overcome these limitations.

Practical implications

Homogenizing the starting powder mixture and the microstructure of the SLS material is the key issue for producing ceramic parts through indirect SLS.

Originality/value

Indirect SLS of ceramics has hardly been reported and the combined use of SLS and QIPing is innovative in the field of indirect SLS of ceramics.

Details

Rapid Prototyping Journal, vol. 18 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article
Publication date: 1 December 1958

WHERE are we going? The aim is to double our standard of living in the next 25 years and, as Sir Alexander Fleck, K.B.E., Chairman of Imperial Chemical Industries Ltd., so…

Abstract

WHERE are we going? The aim is to double our standard of living in the next 25 years and, as Sir Alexander Fleck, K.B.E., Chairman of Imperial Chemical Industries Ltd., so aptly staled recently, ‘The man who knows where he is going is the one who is most likely to arrive.’ One might venture to expand this statement by adding that he is still more likely to arrive if the cluttering debris of inefficient methods and movements are cleared away.

Details

Work Study, vol. 7 no. 12
Type: Research Article
ISSN: 0043-8022

To view the access options for this content please click here
Article
Publication date: 1 December 1965

ONE effect of sharing a common language with America is the imposition of a surfeit of books on matters like work study, in which our own literature is modest indeed. The…

Abstract

ONE effect of sharing a common language with America is the imposition of a surfeit of books on matters like work study, in which our own literature is modest indeed. The almost simultaneous publication of two books with a common subject is therefore very unusual. They both deal with work measurement, one in forty‐seven chapters and the other in fifteen. Since books are not judged by a quantitative standard this is no guide to their respective merits.

Details

Work Study, vol. 14 no. 12
Type: Research Article
ISSN: 0043-8022

To view the access options for this content please click here
Article
Publication date: 1 September 1993

Chris Harris and Brian H. Kleiner

Text book theories of motivation are abundant. Content theories such as Maslow's hierarchy of needs and Herzberg's two factor theory or process theories such as expectancy…

Abstract

Text book theories of motivation are abundant. Content theories such as Maslow's hierarchy of needs and Herzberg's two factor theory or process theories such as expectancy theory and reinforcement theory are practiced in most American companies. The key difference between the best managed companies and other companies is their methods of implementation in their particular environment. Black and Decker, Lincoln Electric, Honeywell, Walmart, Dupont and Phillip Van Heusen are seven of America's best managed companies who use creativity and innovation to motivate employees.

Details

Management Research News, vol. 16 no. 9/10
Type: Research Article
ISSN: 0140-9174

To view the access options for this content please click here
Article
Publication date: 1 September 1995

Martin Fojt

This special “Anbar Abstracts” issue of the International Journal of Physical Distribution & Logistics Management is split into eight sections covering abstracts under the…

Abstract

This special “Anbar Abstracts” issue of the International Journal of Physical Distribution & Logistics Management is split into eight sections covering abstracts under the following headings: Distribution and supply chain management; Logistics; Air/road/rail transport; Retail/wholesale; Freight and delivery services; International; Purchasing; Accounting.

Details

International Journal of Physical Distribution & Logistics Management, vol. 25 no. 9
Type: Research Article
ISSN: 0960-0035

Content available
Article
Publication date: 5 December 2016

David Birnbaum and Michael Decker

Abstract

Details

International Journal of Health Governance, vol. 21 no. 4
Type: Research Article
ISSN: 2059-4631

To view the access options for this content please click here
Article
Publication date: 14 January 2020

Ayokunle Olubunmi Olanipekun, Olalekan Shamsideen Oshodi, Amos Darko and Temitope Omotayo

The development of corporate social responsibility (CSR) in the construction sector is slow, thereby leaving many opportunities for further development. To enable…

Abstract

Purpose

The development of corporate social responsibility (CSR) in the construction sector is slow, thereby leaving many opportunities for further development. To enable operators in the construction sector to effectively capitalise on the opportunities to promote the development of CSR in the sector, this study employs the practice viewpoint to take the stock of CSR activities in the sector. The purpose of this paper is to reveal the state of CSR practice in the construction sector. The study also draws from the development of CSR in the manufacturing, mining and banking sectors to inform the state of CSR practice in the construction sector.

Design/methodology/approach

This study carries out a systematic literature review of 56 journal publications that were published between the year 2000 and 2016. The deductive coding of the publications was done to identify four themes of CSR research that constitute the practice view of the state of CSR in the construction sector.

Findings

The implementation of CSR is the major emphasis in the state of CSR practice in the construction sector. The implementation of CSR is wrapped in the perception of operators about CSR potentials, dimensions of CSR implemented, strategies for implementation and the effects of the implemented CSR practices on performance. The sector characteristics and organisational structure are attributes for comparing the CSR practices between the construction sector and the manufacturing, mining and banking sectors.

Originality/value

This study provides a researchers’ view of the state of CSR in the construction sector. Additionally, the study draws from the development of CSR in the manufacturing, mining and banking sectors to inform the state of CSR practice in the construction sector.

Details

Smart and Sustainable Built Environment, vol. 9 no. 2
Type: Research Article
ISSN: 2046-6099

Keywords

To view the access options for this content please click here
Article
Publication date: 1 August 1993

As with post‐World War II economic policies, boom or bust are terms which can be applied to the birth rate. For those of us who are baby boomers, used to our place in the…

Abstract

As with post‐World War II economic policies, boom or bust are terms which can be applied to the birth rate. For those of us who are baby boomers, used to our place in the demographic spotlight as a focus for endless “what do young people want?” media features, the realization that marketing attention is switching to a new baby bust generation comes as something of a shock. After record births between 1946 and 1964, the rate decreased dramatically between the years 1965 and 1980. This new generation is entering the workforce en masse (albeit a smaller mass than in previous years) about now. Their new‐found spending power is having an impact in consumer markets causing marketers to ask the question “what do young people want?” and causing baby boomers everywhere to realize that, once again, a generation gap has opened up.

Details

Marketing Intelligence & Planning, vol. 11 no. 8
Type: Research Article
ISSN: 0263-4503

1 – 10 of 84