Optimum sintering region for laser sintered nylon-12

Vasquez, Mike; Haworth, Barry; Hopkinson, Neil

doi:10.1177/0954405411414994

Cited by 58 publications

(46 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, an optimum energy density appears to be reached, after which mechanical properties decline due to polymer degradation. Vasquez et al established the term “Stable Sintering Region” to characterize the thermal window for effective laser sintering prior to the onset of significant material degradation [15].…”

Section: Introductionmentioning

confidence: 99%

Methods for quantifying the stable sintering region in laser sintered polyamide‐12

Vasquez

Haworth

Hopkinson

2012

Polymer Engineering & Sci

View full text Add to dashboard Cite

Manufacturing complex parts by the laser sintering process requires a minimum amount of energy input for consolidation of polymer particles to occur; however too much energy can result in a decline in mechanical properties. This decrease is thought to be the result of polymer chain degradation. A stable sintering region (SSR) has been proposed to describe the optimum temperature range for successful laser sintering. This article will aim to quantify the SSR for polyamide‐12 by using thermogravimetric analysis (TGA) to provide a framework for identifying key laser sintering processing parameters. Weight loss with respect to temperature is the main measurement output of the TGA procedure. However, the precise temperature and thermal history of a material is difficult to quantify during the laser sintering process; instead an energy input approach has been developed. A degradation energy was calculated from the TGA data and was used in conjunction with a laser sintering formula called energy melt ratio to prescribe build parameters for laser sintered parts. The mechanical properties of these parts illustrated the effect of degradation at various levels of energy input. Implications for this work include optimizing the material selection process for polymer laser sintering materials beyond polyamide‐12. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

show abstract

Section: Introductionmentioning

confidence: 99%

Methods for quantifying the stable sintering region in laser sintered polyamide‐12

Vasquez

Haworth

Hopkinson

2012

Polymer Engineering & Sci

View full text Add to dashboard Cite

show abstract

“…For 100% crystalline PA12, Gogolewski et al s [12] estimate of the heat of fusion was 209.3 J/g; hence, the PA12 in Figure 1b corresponds to a crystallinity of 53%. Inspection of the literature showed the heat of fusion of commercial PA12 powders disclosed by others was also ≈100 J/g [13]. Thus, for comparable crystallinities of ≈50%, the heat of fusion of the PET will be about half of PA12.…”

Section: Melting and Crystallization Properties Of Pet Powder T1 Commentioning

confidence: 85%

Poly(ethylene terephthalate) Powder—A Versatile Material for Additive Manufacturing

AlFayez

Ahmed

et al. 2019

Polymers

View full text Add to dashboard Cite

The 3D printing of articles by the effect of a directed laser beam on a plastic powder is a demanding process, and unlike injection molding, very few polymers work well enough with it. Recently, we reported that poly(ethylene terephthalate) (PET) powder has intrinsically good properties for 3D printing. Basic mechanical properties were shown earlier and it was demonstrated that unfused but heat-exposed PET powder does not degrade quickly allowing good re-use potential. In this work, we conducted a detailed comparison of the mechanical properties of PET and polyamide 12 from different build orientations. PET powders with two different molecular weights were used. With the high molecular weight powder, the processing parameters were optimized, and the printed bars showed little difference between the different orientations, which means there is low anisotropy in mechanical properties of built parts. Based on processing experience of the first powder, the second powder with a lower molecular weight was also very printable and complex parts were made with ease from the initial printing trials; since the process parameters were not optimized then, lower mechanical properties were obtained. While the intrinsic material properties of PET (melting and re-crystallization kinetics) are not the best for injection molding, PET is eminently suitable for powder bed fusion.

show abstract

“…Subsequently, a theoretical approach using the Kissinger technique (based upon energy melt ratio data) has been proposed to define upper temperature limits in laser melting PA12 more precisely (Vasquez et al, 2013). Mechanical properties of melted parts, using any polymer types, are likely to be optimised within the stable melting region (Vasquez et al, 2011), but before the upper temperature limit. In conventional laser melting, polymer powders need to be pre-heated before being melted and thermal energy is provided by a powder bed, usually held at a temperature below the melting point (T m ) of semi-crystalline polymers.…”

Section: Materials Selection For Laser Melting Processesmentioning

confidence: 99%

Selective laser melting using holographic beam manipulation: influence of polypropylene molecular weight

Haworth

Tyrer

Zhou

2018

RPJ

View full text Add to dashboard Cite

Purpose-There is a requirement to match selective laser melting (SLM) technologies to a wider range of polymeric materials, since the existing market for SLM powders is dominated by polyamide PA12. Drivers include the tailoring of physical properties to individual applications, or cost reduction. Polypropylene (PP) currently has limited use in SLM, so the potential use of PP materials of varying molecular weight (Mw) is explored here. Design / methodology / approach-PP polymers of differing molecular weight were characterised using a range of analytical techniques, including DSC, thermogravimetric analysis (TGA), rotational rheometry and real-time hot-stage (optical) microscopy. Findings-The techniques are sufficiently sensitive to distinguish molecular weight effects, notably in terms of material viscosity. The stable sintering region for SLM has been defined clearly. Some success was achieved in melting parts using some grades of PP, including higher molecular weight grades, which potentially offer improved mechanical performance. Research limitations / implications-The range of techniques (DSC, OIT and TGA) form an effective analytical package with which to consider new polymeric materials for SLM. Practical implications-High-MW PP polymers, in tape or powder form, have potential use in SLM processes, providing scope to enhance part properties in future. Originality / value-This is believed to be the first in-depth study noting the influence of PP molecular weight on important physical performance in a proprietary SLM process, using holographic beam manipulation (HBM).

show abstract

Optimum sintering region for laser sintered nylon-12

Abstract: between machine parameters and part properties. This work aims to improve that understanding by discussing the pattern of thermal behaviour, including degradation, seen in polyamide exposed to high laser parameters.

Cited by 58 publications

References 13 publications

Methods for quantifying the stable sintering region in laser sintered polyamide‐12

Methods for quantifying the stable sintering region in laser sintered polyamide‐12

Poly(ethylene terephthalate) Powder—A Versatile Material for Additive Manufacturing

Selective laser melting using holographic beam manipulation: influence of polypropylene molecular weight

Contact Info

Product

Resources

About