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Article
Publication date: 14 December 2018

Tomaz Brajlih, Urska Kostevsek and Igor Drstvensek

One of the main problems of selective laser sintering (SLS) manufacturing process is the dimensional accuracy of products. Main causes of dimensional deviations are material…

289

Abstract

Purpose

One of the main problems of selective laser sintering (SLS) manufacturing process is the dimensional accuracy of products. Main causes of dimensional deviations are material shrinkage and size of laser heat affected zone (LHAZ). This paper aims to present a new method of adapting SLS manufacturing shrinkage and LHAZ compensation parameters to the geometrical characteristics of processed parts to improve their accuracy.

Design/methodology/approach

The first part of this work presents a hypothesis asserting that the shrinkage and the LHAZ size depend on geometrical properties of products. A method that defines geometrical properties by numerical influence factors is described in the continuation. A multi-factorial experiment with adaptable test part is set up. Then, test builds are manufactured on an SLS machine and measured with a three-dimensional optical scanner. Afterwards, the results are analysed in relation to the presumed hypothesis.

Findings

The analysis of variance of multi-factorial experiment proves the hypothesis and the influence of the geometrical properties on the accuracy of the SLS manufacturing process. Afterwards, a part is manufactured with adapted values of compensation parameters and the archived accuracy is discussed.

Research limitations/implications

Presented research is limited on a single SLS material. Also, some numerical factors are directly linked to the build volume dimensions of the SLS machine that was used in the experiment. However, results can be generalised and some guidelines for shrinkage and LHAZ compensation method are presented. Also, some guidelines for future research are proposed.

Practical implications

Based on the presented results, it can be determined that using constant shrinkage and LHAZ values on an SLS machine will not yield the same results in terms of accuracy if the geometrical properties of parts change significantly.

Social implications

By correctly adapting compensation values, the overall achievable accuracy of the SLS process can be achieved, enabling a more reliable production of mass-customised end-user parts such as customised medical accessories and devices for example.

Originality/value

A similar method of numerically describing geometrical properties of part in regard to SLS and directly adapting shrinkage and LHAZ compensation values to them for every individual build has not yet been proposed.

Details

Rapid Prototyping Journal, vol. 25 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 9 April 2018

Urska Kostevsek, Tomaz Brajlih, Joze Balic, Žiga Kadivnik and Igor Drstvensek

Fixed structures in prosthetic dentistry are highly customized products, manufactured individually for patients who have missing teeth. When choosing the technology for fixed…

225

Abstract

Purpose

Fixed structures in prosthetic dentistry are highly customized products, manufactured individually for patients who have missing teeth. When choosing the technology for fixed dental structure manufacturing, three viable options are available (precise casting, milling and selective laser melting [SLM]). All these technologies can be used to produce a dental structure from CoCr alloy. Besides materials and availability of technologies, economic efficiency is an important factor when choosing a production method. The purpose of this study is to develop an estimation model for achievable productivity of selective laser melting and compare the results with the productivity of conventional manufacturing.

Design/methodology/approach

Results presented in this paper are based on manufacturing time analysis of an individual case with each of the technologies mentioned above. Because of the efficiency of SLM is highly dependent on how efficiently the work space of the machine is used, this issue was also included in the research. Data used for research were acquired from practical use of each technology in dental applications.

Findings

Analysis of achievable SLM manufacturing speeds is based on the previous research into manufacturing speeds of additive manufacturing technologies. The presented results present a model that can be used to estimate the productivity of the SLM technology.

Research limitations/implications

Research was limited to a specific SLM machine type with a fixed workspace volume. Nevertheless, the results show that any SLM machine has to be used as efficiently as possible to be able to be competitive regarding the conventional manufacturing technologies.

Practical implications

The presented results show clearly at least a rough estimation of what kind of parts and in what volume will be manufactured with an SLM machine prior to buying one.

Social implications

Results can help to widen the economically efficient way of running SLM machines, replacing conventional manufacturing for medical applications especially with complicated cases.

Originality/value

A method is presented to adapt the estimation model to a particular real-life production scenario. This method can be used to establish how efficiently selective laser sintering can be used and if using SLM machine instead of conventional manufacturing would be economically viable.

Details

Rapid Prototyping Journal, vol. 24 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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