Dependence of mechanical properties of polyamide components on build parameters in the SLS process

“…Ho et al [3] evaluated the effect of the Energy Density (ED) parameter on polycarbonate structures, while a similar approach was adopted by Drummer et al [4,5] and Caulfield et al [6] for the analysis of PA structures. Most of them focussed on the influence of ED on the mechanical performance of laser sintered parts and the main outcome from these studies was that an increase of the ED caused the mechanical properties, especially tensile strength, to improve up to a value where they stabilise or slightly decrease.…”

Section: Introductionmentioning

confidence: 99%

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

2016

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New materials for Laser Sintering (LS) are usually developed using a trial and-error approach that consists of a series of builds within LS systems. This strategy is time consuming, costly and focuses only on the optimisation of the processing parameters, ignoring the powder properties of the materials under examination. Being able to predict processing parameters on the basis of the powder material properties would enable a faster development of new materials and new applications, while acknowledging a more in-depth understanding of the mechanisms involved in LS. This paper provides new results into the prediction of processing conditions from the material properties. It is here shown that high temperature polymers such as Poly Ether Ether Ketone (PEEK) and Poly Aryl Ether Ketone (PEK) can be successfully used in LS despite the lack of a super-cooling window. The evaluation of the stable sintering region of PEEK 450PF and the application the energy melt ratio parameter in relation to the mechanical performance of laser sintered PEEK samples are also provided. Lastly, a new method for estimating the powder bed temperature is proposed.

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“…It has been shown that the density, and the mechanical properties, of laser sintered nylon-12 parts increase with laser power [10,11]. As laser power increases, melt temperature is raised, viscosity would be expected to reduce, and improved melt flow leads to more effective sintering and higher densification.…”

Section: Density and Porositymentioning

confidence: 99%

Fracture mechanics approach to compare laser sintered parts and injection mouldings of nylon-12

Hitt

Haworth

Hopkinson

2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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Abstract:In comparison to equivalent parts made by injection moulding (IM), components manufactured by laser sintering (LS) are often perceived to offer inferior mechanical properties, yet the evidence for this is rarely based upon systematic research studies. In this paper, attempts have been made to conduct a fundamental study of the fracture behaviour of both injection moulded and laser sintered parts, based upon a modification of a standard technique used to determine linear elastic fracture mechanics (LEFM) parameters. The influence of specimen thickness (in the range 2-10mm) was also included in the experimental plan, which was concentrated upon the testing of single edge notch bending (SENB) beam specimens.Force-displacement characteristics demonstrated significant plastic deformation in nylon (PA12) specimens, so that the J-integral method was used to obtain quantitative fracture parameters, including the energy requirements for crack growth. Comparisons of this parameter showed thickness dependent, 'geometry-sensitive' data for each set of samples. For the injection moulded SENB specimens, energy absorption decreased with increasing thickness, a result attributed to the influence of plane strain dominated conditions. In contrast, laser sintered samples exhibited increased toughness as specimen thickness increased towards 10mm; this could not be explained by density or particle melting data and may be interpreted by changes in molecular structure that occur during the additive manufacturing process.

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Dependence of mechanical properties of polyamide components on build parameters in the SLS process

Cited by 482 publications

References 10 publications

Effect of bed temperature and infra-red lamp power on the mechanical properties of parts produced using high-speed sintering

Effect of bed temperature and infra-red lamp power on the mechanical properties of parts produced using high-speed sintering

Predicting processing parameters in high temperature laser sintering (HT-LS) from powder properties

Fracture mechanics approach to compare laser sintered parts and injection mouldings of nylon-12

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