Enhancing dewatering rate of moulded fibre screens for precise shaping

• Main Author: Tan, Yang Jon
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering::Fluid mechanics; Engineering::Mechanical engineering::Prototyping; Engineering::Manufacturing::Product design
• Online Access: https://hdl.handle.net/10356/167774
• Institution: Nanyang Technological University

This Final Year Project aims to investigate how process parameters such as screen thickness, hole shape and slurry material affect dewatering rates of moulded fibre screens via Multi Jet Fusion. Multi Jet Fusion is an alternative manufacturing method to Computer Numeric Controlled Screens (CNC) and dewatering rates must be sufficient for it to be viable in the Moulded Pulp Product (MPP) industry. Two main types of slurry material, paper and banana leaves were tested. Dewatering rates for banana leaves were significantly higher than paper due to poor fibre entanglement and air gaps. This is evidenced in the microstructure images where the layer formed is uneven unlike paper which is uniform. Dewatering rates of paper slurry is estimated to be 20000mm3 on average as compared to banana leaves slurry which is about 100000mm3, making deductions inaccurate. However, changes in trends when another material aside from paper is used can be analysed despite its credibility. Other materials not included in this project can also be considered with the right pulping method. This project identified the optimal hole choices for screens of varying thickness. Through experiment iterations, it was found that screens with swirl feature and square holes tend to perform better at higher thickness. Conversely, through hole designs have a better dewatering rate at lower thickness of 1mm. Square holes increases or decreases depending on its hole shape. ST designs perform the best regardless of hole design and thickness, while FL and CR perform better at lower and higher thickness respectively. In terms of screen thickness, increasing it generally improves dewatering rate but the hole design must still be taken into consideration. Surprisingly, there is no correlation between fibre height and dewatering rate. Many hole designs are yet to be tested but a main area for future research includes the surface geometry of the screen due to the lack of available research and potential in improving dewatering rate.