The efficacy of wood dust fibre treatment on the property of wood dust reinforced recycled polypropylene composite (r-WoPPC) filament was investigated. The wood dust fibre was treated using alkali, silane, and NaOH-silane. The treated wood fibre was incorporated with r-PP using a twin-screw extruder to produce filament. The silane treatment on wood dust fibre enhances interfacial bonding between wood fibre and recycled PP; hence, a filament has the highest wire pull strength, which is 35.2% higher compared to untreated and alkaline-treated wood dust filament. It is because silanol in silane forms a siloxane bond that acts as a coupling agent that improves interfacial bonding between wood dust fibre and recycled PP. The SEM micrograph of the fracture structure reveals that treated silane has strong interfacial bonding between wood dust fibre and recycled PP, having minimal void, gap, and good fibre adhesion. The water absorption test results indicate that filament with treated wood dust absorbs less water than filament with untreated wood because the treatment minimizes the gap between wood fibres and recycled PP. The FTIR analysis identified the presence of silane on the wood dust surface for silane-treated wood dust. The DSC studies suggest that the temperature range 167–170 °C be used in the extrusion machine to produce r- WoPPC filament. As a result, r-WoPPc filaments containing silane-treated wood dust have better mechanical properties and have a greater potential for usage in FDM applications.

The employment of natural fibres in fused deposition modeling has raised much attention from researchers in finding a suitable formulation for the natural fibre composite filaments. Moreover, selection of suitable natural fibres for fused deposition modeling should be performed before the development of the composites. It could not be performed without identifying selection criteria that comprehend both materials and fused deposition modeling process requirements. Therefore, in this study, integration of the Analytic Hierarchy Process (AHP)/ Analytic Network Process (ANP) has been introduced in selecting the natural fibres based in different clusters of selection concurrently. The selection process has been performed based on the interdependency among the selection criteria. Pairwise comparison matrices are constructed based on AHP's hierarchical model and super matrices are constructed based on the ANP's network model. As a result, flax fibre has ranked at the top of the selection by scored 19.5% from the overall evaluation. Flax fibre has excellent material properties and been found in various natural fibre composite applications. Further investigation is needed to study the compatibility of this fibre to be reinforced with a thermoplastic polymer matrix to develop a resultant natural fibre composite filament for fused deposition modeling.

Fused filament fabrication (FFF) has been developed in additive manufacturing technology as a fast and simple manufacturing process in product design. Advantage of the process such as flexibility in terms of the materials employment has attracted many researchers to develop new materials for the feed stock filament in the heat extrusion process of FFF. Green materials or bio-composites materials have been found in FFF and successfully commercialized in the market. However, a deep research should have been performed prior the application because of the unique characteristics of the material itself. The challenge for the researchers to develop bio-composite materials as the filament in FFF technology is to determine the right composition of the composites with the right thermal, mechanical, and rheological properties. Therefore, in this study, a review has been conducted to highlight the important requirements of the process and materials. Green materials such as bio-composites have a great potential in the FFF technology and could improve the sustainability impact.

High deposition rate with minimal heat input is one of the primary emphasis in wire arc additive manufacturing. This study aims to determine the optimal input parameters of micro plasma welding for single-layer deposition. The stability of a single layer is crucial as it serves as the foundation to the multi-layers deposition in producing 3D additively manufactured structure. The study focuses on wire feeding speed, welding speed, and pulse and their interaction between the input and response variables. Based on the study, the regression equation between the three key parameters and the response using the Box-Behnken Design response surface methodology was proposed. The outcome demonstrates that the optimized sample deposition produces a smooth surface appearance with no apparent defects. additive manufacturing 3D printing wire arc additive manufacturing micro plasma arc welding response surface methodology

The thermal behaviour of filament materials is one of the most important characteristics to study to produce quality filament since the FDM process strongly relies on heating operations such as mixing and printing. To develop composite filament FDM using recycled polypropylene and wood dust fibre (r-WoPPc), the thermal properties of these recycled materials were investigated. Wood dust and recycled PP are by-products of the furniture and plastics industries, and their thermal characteristics may change during manufacturing. Furthermore, wood dust is typically subjected to several cleaning and treatment processes to have a cleaner and impurity-free dust as well as better adhesion with the recycled PP matrix, which both processes may affect its thermal properties. Therefore, TGA and DSC analyses are conducted to ensure its thermal properties before developing the filament. Untreated, NaOH and silane treated wood dust and recycled PP was subjected to TGA and DSC analyses. Wood dust treated with silane had the highest combustion resistance at 372°C compared to untreated wood dust at 360°C and NaOH treated at 320°C. Meanwhile, DSC analysis of recycled PP indicated that it melted at 167°C, which was used to establish the filament extrusion and printing temperatures. In a conclusion, these studies provided a point of reference for determining filament extrusion and printing temperatures.