Mengqi Yuan

Optical properties of laser sintered polyamide 12

Purpose – The purpose of this paper is to report selected optical properties of laser sintered polyamide 12 blank plates under different monochromatic and white light conditions and to apply these properties in production of laser sintered lithophanes. Design/methodology/approach – A UNICO 1201E spectrophotometer was used to measure the transmittance of laser sintered polyamide 12 plates as a function of plate thickness. Monochromatic light-emitting diodes were used to assess the wavelength dependence on the transmission and contrast as captured by a SONY DSC-W55 camera. Findings – The transmittance decreased with increasing plate thickness which varied significantly depending on the monochromatic wavelength. Highest transmission was observed using green light (525 nm) and poorest transmission was measured for yellow light (589 nm). Research limitations/implications – There is a limit to the amount of contrast obtained in polyamide lithophanes because the thickness of the plates is limited to less than ab...

Orientation effects for laser sintered polyamide optically translucent parts

Purpose – This paper aims to analyze the additive manufacturing orientation effect of laser sintered polyamide 12 (PA 12) optically translucent parts. Design/methodology/approach – Plates with small features, wedges and lithophanes were laser sintered on a SinterStation HiQ™ in different orientations using PA 12. Lithophane performance was assessed using a Picker 240050 X-ray view/light box. All parts were examined using stereomicroscopy to capture the small features. Findings – The quality of the lithophane image was substantially improved by orienting the flat plate side to the incident backlit light. Sintering in the ZX/ZY plane significantly increased the contrast and resolution compared to sintering in the XY plane. The thinnest feature thickness possible in the SinterStation HiQ is in the XY plane 0.13 mm, and it is 0.57 mm when manufacturing in the ZX/ZY plane. Research limitations/implications – The laser spot size and other machine parameters were not changeable, which limited the manufacturing r...

Quality improvement of optically translucent parts manufactured from LS and SL

Purpose – The purpose of this paper is to improve the quality of additive manufactured optically translucent parts by investigating the manufacturing issues, analyzing lithophane production criteria and identifying the best translucent material and additive manufacturing (AM) technology. Design/methodology/approach – Figured lithophanes were laser sintered on a 3D Systems SinterStation® HiQ™ with varying layer thickness and plate thickness. Laser sintered (LS) polyamide (PA) 12 blanks were cyanoacrylate infiltrated and polished. Optical properties and performance were compared with the original LS blanks. Lithophanes and blanks were manufactured using 3D systems stereo lithography apparatus (SLA)® Viper ™si2 station, and optical properties and lithophane performance were compared with the LS specimens. Findings – When building in the XY plane, it is optimal to sinter with the minimum layer thickness (0.076 mm) and maximum plate thickness (5 mm). Cyanoacrylate infiltration and polishing assists in reducing...

The application of PA/CF in stab resistance body armor

Stab resistance body armor (SRBA) is an essential defensive equipment to protect human body against injuries from stabbing. The conventional SRBAs shared low wearing frequency since they are heavy and poor in flexibility. This paper designed a structured stab-resistance plate using the model of crocodile armor and manufactured using 3D printing technology-laser sintering (LS). CF(Carbon fiber) was applied to enhance the stab resistance properties of SRBA. The effects of the material and structure were analysed through the stab resistance property tests based on the national standard GA68-2008. It is found that the stab resistance property of flat plates sintered by PA powder and PA/CF are both weaker than that of the structured plate. The penetrating depth of PA/CF structured plate is significantly 2-mm-less than the pure PA structured plate. The SEM observations confirmed the conclusion that addition of the CF largely improved the plate stab resistance property. Moreover, using PA/CF structured plate to produce the stab resistance body armor would result in a weight reduction by about 30-40% as compared to the existing SRBA that was made up of metal plates, which could largely reduce the wearer physical burden and improve the wearing frequency.