Additive manufacturing methods has gained tremendous attention over the last decade, with newly established standards bringing such methods notoriety across a range of industrial sectors, such as aerospace, automotive, medical, construction, and so on. One of the most widely used category of additive manufacturing is known as ‘material extrusion’ – most commonly referred to as ‘3D printing’. 3D printing is characterised by the process of fused filament fabrication (FFF) or fused deposition modelling (FDM), and carried out by using a 3D printer.
These machines are easy to use and modify, allowing users to produce different products with varying properties such as different shapes, colours and sizes. This magic happens when the machine extrudes a thermoplastic filament and deposits it on what is known as a ‘print bed’ to manufacture the desired product. Hobbyists and commercial entities have made good use of such systems to establish the effectiveness of the FFF process, due in large part to its affordability and wide selection of material.
So, what’s the problem?
Due to the abundance of materials and development of new composite filaments, it has become exceeding difficult to identify the optimal process parameters to achieve the desired results. Most of the raw materials come with standard recommendations from the manufacturers in terms of their extrusion temperature, but the majority of parameters are determined through the eternal process of trial-and-error. This is time-consuming and can lead to significant wastage of material.
To expand on this in more detail, the default setting on most 3D printers with a 0.4 mm nozzle is 0.2mm layer height and 0.4mm line width (equal to the nozzle diameter). However, modifying these two parameters can drastically alter the properties of the printed parts in terms of their surface finish and mechanical properties.
How can we solve this?
To overcome the shortfalls of the 3D printer’s default settings and be able to achieve the desired results in FFF-printed thermoplastics, the research we undertook investigated the effects of layer height and line width on a number of different thermoplastic materials: Premium PLA, Haydale’s Synergy Graphene Enhanced PLA, ABS Extrafill and ASA Extrafill. These materials have been manufactured using Anet® ET4 Pro 3D printer at four different layer heights (0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm) and five different line widths (0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm). They were tested according to British and International standards for this study including effects on mass, dimensional accuracy, surface texture, and mechanical properties.
Significance of results
A comprehensive comparative study on the four thermoplastics materials as a function of four different layer heights and five different line widths has demonstrated that trade-offs can be made with the different materials. This can be in terms of surface finish, mechanical properties, and manufacturing time, all achieved by modifying the layer heights and line widths. As both parameters directly influence each other, their optimal combination changes for different properties. For example, the optimal surface finish is observed at 0.4 mm line width for PLA at all layer heights, whereas 0.6 mm line width showed the optimal surface finish for all the other three materials. Similarly, higher tensile strength was observed at larger line widths for all the materials. Therefore, to observe good surface finish, tensile strength would need to be compromised and vice versa. These results are extremely beneficial for designers and manufacturers as they allow for a better understanding of the different process parameters and their effects on the properties of four different thermoplastic materials.