Experimental and theoretical studies of selective laser sintering

Childs, T.H.C.; Ryder, G.; Berzins, Martin

doi:10.1007/978-1-4615-6379-2_12

Cited by 7 publications

(7 citation statements)

References 6 publications

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“…The model of how thermal conductivity varies with part density is more important. In earlier publications [7][8][9], coefficients a and b in equation (5c) were assumed (without any evidence) to be 0.5 and 0 respectively. Table 2 shows how these values lead to slightly changed predictions.…”

Section: Discussionmentioning

confidence: 99%

“…The parts were made at various laser powers, scan speeds and scan spacings, from 6 to 14 W, 520 to 1200 mm/s and 0.1 to 0.4 mm respectively, to give energy densities P/(Us) delivered by the laser of 0.035-0.125 J/mm 2 . (Previous work [5,8,9] and the structure of equation ( 6), with equation (1a), suggests that, for a given beam diameter, sintering depends on the laser scanning variables mainly through P/(Us)). The first layer of a part was supported in position in the powder bed by a standard method, by building it on a base.…”

Section: Sintering Experimentsmentioning

confidence: 99%

“…However, what is appropriate depends on whether the prediction of density or size accuracy is the purpose of the analysis. Some of this work has been published before in conference proceedings [5,[7][8][9]. With the passage of time, some assumptions made initially have been proved to be unfounded; some errors have been detected.…”

Section: Introductionmentioning

confidence: 99%

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Selective laser sintering of an amorphous polymer—simulations and experiments

Childs

Berzins

Ryder

et al. 1999

Proceedings of the Institution of Mechanical Engineers, Part B:

133

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Thermal and powder densification modelling of the selective laser sintering of amorphous polycarbonate is reported. Three strategies have been investigated: analytical, adaptive mesh finite difference and fixed mesh finite element. A comparison between the three and experimental results is used to evaluate their ability reliably to predict the behaviour of the physical process. The finite difference and finite element approaches are the only ones that automatically deal with the non-linearities of the physical process that arise from the variation in the thermal properties of the polymer with density during sintering, but the analytical model has some value, provided appropriate mean values are used for thermal properties. Analysis shows that the densification and linear accuracies due to sintering are most sensitive to changes in the activation energy and heat capacity of the polymer, with a second level of sensitivities that includes powder bed density and powder layer thickness. Simulations of the manufacture of hollow cylinders and T-pieces show feature distortions due to excessive depth of sintering at downward facing surfaces in the powder bed. In addition to supporting the modelling, the experiments draw attention to the importance of sintering machine hardware and software controls.

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Section: Discussionmentioning

confidence: 99%

Section: Sintering Experimentsmentioning

confidence: 99%

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Selective laser sintering of an amorphous polymer—simulations and experiments

Childs

Berzins

Ryder

et al. 1999

Proceedings of the Institution of Mechanical Engineers, Part B:

133

View full text Add to dashboard Cite

show abstract

“…2 Several studies have attempted to predict the density of parts produced using the LS process. [10][11][12][13][14][15][16]…”

Section: Densitymentioning

confidence: 99%

An investigation on the suitability of micro-computed tomography as a non-destructive technique to assess the morphology of laser sintered nylon 12 parts

Rouholamin

Hopkinson

2014

Proceedings of the Institution of Mechanical Engineers, Part B:

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This research study investigates the suitability of micro-computed tomography as a non-destructive technique to assess the morphology of nylon 12 parts manufactured using laser sintering. Density measurements and morphological and mechanical characterisations were performed on sintered nylon 12 parts to measure density and morphological and mechanical properties of the parts. The effects of various levels of laser power on the density, morphological parameters and mechanical properties were investigated and compared. The results show that micro-computed tomography can be used to measure the porosity and pore size of the sintered parts. Micro-computed tomography images provide an understanding of the changes in the three-dimensional structure of the parts. There is no evident change in the porosity or pore size of the laser sintered parts with the increase in laser power. The results of the tensile tests show that the changes applied in laser power had no apparent effect on the ultimate tensile strength and Young’s modulus of the laser sintered parts. However, the elongation at break for the parts generally increases as the level of laser power increases. A relationship between non-destructive micro-computed tomography and destructive tensile test results is shown.

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“…The main disadvantage of this technique is that it is a two-step process for the fabrication of metallic parts. The recently developed new technology of selective laser sintering [4,5] and laser generating [6,7] oers the possibility of direct fabrication of metallic parts and rapid prototype products in a single step process. In this case, a correct amount of material is deposited/sintered precisely when and where needed to build the part gradually as a series of successive horizontal layers formed individually and bonded to the preceding layer.…”

Section: Introductionmentioning

confidence: 99%

Metal rapid prototyping via a laser generating/selective sintering process

Kathuria¹

2000

Proceedings of the Institution of Mechanical Engineers, Part B:

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During the last decade, developments in rapid prototyping and rapid manufacturing techniques have undertaken a new dynamic turn in production technology. Besides the use of new and better performance materials, process development techniques are increasing further so as to reduce the iteration cycle of the product and production process. In this paper, based upon the selective laser sintering/generating process, certain new features of the fabrication of metal or metal matrix composite parts using CO2/Nd-YAG lasers are discussed. The basic process of beam interaction with the metallic powder is investigated, and results concerning the microstructure and shape factor are interpreted.

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Experimental and theoretical studies of selective laser sintering

Cited by 7 publications

References 6 publications

Selective laser sintering of an amorphous polymer—simulations and experiments

Selective laser sintering of an amorphous polymer—simulations and experiments

An investigation on the suitability of micro-computed tomography as a non-destructive technique to assess the morphology of laser sintered nylon 12 parts

Metal rapid prototyping via a laser generating/selective sintering process

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