3D printing can help users quickly and economically manufacture prototypes and parts needed for a variety of applications, but choosing the right 3D printing process is only one aspect. Whether the final part can be made with the desired mechanical properties, functional characteristics or appearance depends largely on the material used.
This comprehensive guide to 3D printing materials describes the most popular plastic and metal 3D printing materials, compares their properties and applications, and provides guidelines that can be used to select the right material for your project.
Plastic 3D printing materials and processes
There are dozens of plastic materials that can be used for 3D printing, and each material has its own unique characteristics that are suitable for specific use cases. To simplify the process of finding the best material for a given part or product, we first need to understand the major plastic types and the different 3D printing processes.
Plastic material type
There are two main types of plastics:
Thermoplastics are the most commonly used type of plastic. Compared with thermosetting plastics, their biggest difference is that they can withstand countless melting and solidification cycles. Thermoplastics melt when heated so that they can be made into the desired shape. No chemical bonding occurs in this process, so it is a reversible process, which makes it possible to recycle, melt and reuse thermoplastics. Thermoplastics are often compared to butter, a material that can be melted and solidified over and over again. But with each melting cycle, the properties of the material change slightly.
Thermosetting plastics that remain permanently solid after curing. Polymers in thermosetting materials undergo cross-linking reactions during a curing process triggered by heat, light, or appropriate radiation. Therefore, the material will decompose rather than melt when heated, and will not deform after cooling. Thus cannot be recovered or restored to the base ingredients. Thermosetting materials are like cake batter; once baked, they cannot be melted back into batter.
Plastic 3D printing process
At present, the most mature plastic 3D printing process has the following three:
In fused deposition molding (FDM), the 3D printer extrudes the thermoplastic filament after melting it, and then the printer nozzle deposits the thermoplastic filament layer by layer on the formed area.
Stereoscopic light curing (SLA), a 3D printer uses a laser to cure a liquid thermosetting resin into a hardened plastic, a process called photopolymerization.
Selective laser sintering (SLS), a 3D printer uses a high-power laser to fuse small particles of thermoplastic powder.
FDM 3D printing technology
Fused deposition molding (FDM), also known as fuse manufacturing (FFF), is the most widely used form of 3D printing among the consumer community, and the emergence of amateur 3D printers has accelerated the development of this technology.
The technology is well suited for basic proof-of-concept models, as well as rapid and low-cost prototyping of simple parts.
Compared to other plastic 3D printing processes, consumer FDM has the lowest resolution and accuracy, so it is not suitable for printing complex designs or parts with fine features. The quality of surface treatment can be improved by chemical and mechanical polishing processes. Industrial FDM 3D printers use soluble supports to alleviate some of these issues and provide richer engineering thermoplastics or composites, but they are expensive.
When the melted filament forms each layer, sometimes the layers cannot be fully bonded, resulting in a gap. This results in anisotropy in the parts, which must be considered when designing parts that are subject to load or tension.
FDM 3D printing materials are available in a variety of colors, as well as a variety of experimental plastic filament mixing schemes that can be used to create parts with surfaces similar to wood or metal.
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