Effect of layer thickness on the mechanical properties of laser sintered PA12

• Main Author: Lee, Shin Da
• Other Authors: Zhou Kun
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68913
• Institution: Nanyang Technological University

Being the trendiest Additive Manufacturing method in industry application as its wide material range availability and complex shape printing ability, Selective Laser Sintering still has extensive range of unidentified properties in the material and process factor employed. The author has conducted several mechanical testings include tensile testing, impact testing and hardness testing to determine the effect of layer thickness on Polyamide 12 (PA12). Additionally, degree of crystallization of material in various section thicknesses with two categories of layer thickness (100 and 120µm) were obtained by differential scanning calorimetry and to explain the outcome of mechanical testings. The polished surfaces of PA12 with different layer thicknesses were also observed by the author under optical microscope. Results indicated that the thicker layer presents a brittle behavior leads to slight higher tensile properties on the contrary noticeable lower toughness and ductility. The more crystalline region and higher porosity in greater layer thickness are the explanations of more brittle manner. The thinner layer thickness specimens have better sintering efficiency to reduce porosity but during re-crystallization, it processes faster cooling rate that causes lower crystallinity. Insignificant difference of hardness was found between two layer thicknesses. The larger width specimens appeared to have a higher impact strength caused by heat retention during sintering process however hardness and crystallization of material do not vary with section thickness.