A study on recycling of waste polyamide 12 powder into 3D printing filaments

Abstract

Over decades, 3D printing technology develops dramatically and is one of modern processing nowadays. 3DTech Company provides 3D printing products by using Multi Jet Fusion (MJF) technique. In this technique, nylon polyamide 12 (PA12) powders are used as main material due to its high-quality properties. In this thesis, researches in safety handling with fine powder in laboratory and recycling of waste powders were conducted. The aims of the thesis are safety handling with fine powder in lab, research in degradation properties of waste powder, and recycling waste powder into filaments. Waste PA12 powders are microparticles, thus safety working with this fine powder in lab is highly concerned because of its inhalation affects and explosion characteristic. However, after processing, a huge amount of unmolten powder turns into waste. Besides, a research in degradation of unmolten powders are declared in this thesis. During MJF, unmolten powders suffer for a certain time in very close to melting point. For this reason, viscosity of PA12 powder decreases due to increasing in molecular weight. Additionally, MJF works in oxygen environment, thus oxidation occurs during printing. In this thesis, moisture absorption characteristic of waste PA12 was conducted by a hot-air drying oven and Melt Flow Rate of waste PA12 powder was tested in Arcada lab. In order to enhance quality properties of waste PA12 powder, the topic Development of filaments using selective laser sintering waste powder is mentioned in this thesis. The authors used Tungsten carbide (WC) as added reinforcement material and they applied a filament-making machine to fabricate filaments from waste powders. The authors also declaired that the recycled filaments are appropriated for Fused Depositon Modeling (FDM) method with suitable required properties. Regarding with recycled filaments were made, the waste PA12 powders can be recycled by adding reinforcement material and processed into filaments by using a filament-making machine.