Showing papers by "John R. Tyrer published in 2017"

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

Abstract: Purpose There is a requirement to match selective laser melting (SLM) technologies to a wider range of polymeric materials, as 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, this paper aims to explore the potential use of PP materials of varying molecular weight (Mw). Design/methodology/approach PP polymers of differing Mw were characterised using a range of analytical techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rotational rheometry and real-time hot-stage (optical) microscopy. Findings The techniques are sufficiently sensitive to distinguish Mw 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 all grades of PP, including higher Mw grades, which potentially offer improved mechanical performance. Research limitations/implications The range of techniques (DSC, oxidative induction time 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 Mw on important physical performance in a proprietary SLM process, using holographic beam manipulation.

CO2 laser dye patterning for textile design and apparel manufacture

Abstract: Digital dyeing technique, described as ‘Digital Laser Dyeing’ (DLD) was studied in this research using CO2 laser technology, synthetic textiles, workshop coloration methods and industry standard dyes and dyeing procedures. Laser beam energy was used as an image creation tool to modify surface fibres with graphic patterns and coloured dyed effects through a Computer Aided Design (CAD) approach. The research was supported by a textile design perspective in order to explore the creative potential of DLD methods for textile processing, fabric finishing, fashion design and apparel manufacture. Combined technical and scientific inquiry ensured experimental rigor in terms of the repeatable methods employed and reliable results achieved using an energy density (J/cm2) approach. Outcomes of the study identified CO2 laser-dye patterning as an innovative alternative textile coloration approach and dye on demand manufacturing process relevant to textile and clothing production. Explorations with polyester/elastane sportswear and intimate garments in this study suggest a potential sector for the development of on demand processing for synthetic textiles and clothing.