What are FDM Thermoplastics?

November 10, 2017
What are FDM Thermoplastics?

Additive manufacturing technology is the new kid on the block, relatively speaking. The process uses fused deposition modelling (FDM) technology to deposit successive layers of material on top of each other to form prototypes and production-grade components. The principles in use here are not intended to replace injection moulding equipment or CNC tools. Instead, the technology exists as a companion production process, a means of turning an amorphous polymer into a geometrically accurate model, one that incorporates polymer-imbued properties.

Layering Magic

Key characteristics define FDM thermoplastics. If a 3D printed product, for example, is to be built from nothing, then layers of plastic are extruded and built on top of each other. Unfortunately, this would only form a weak structure made from hundreds of thin laminations. The fuse deposition process strengthens the layers by melting a special thermoplastic until it reaches a semi-liquid state. This FDM-rated material instantly returns to its solid state once deposited, which creates a strong scaffold, one that’s solid and free of structure-weakening laminations.

The Properties of FDM Thermoplastics

Durable ABS polymer families and fatigue-resistant polycarbonate groups are commonly classed as fused deposition modelling materials, but there are many other engineering plastics that fit this classification. They exhibit dense molecular structures but melt and become moldable when employed as part of a 3D printing cycle. The fusing properties of each sourced plastic supports thin layering attributes, high strength-to-weight ratios, and all of the other properties that empower the additive engineering process we refer to as 3D printing.

Application-Oriented Versatility

As mentioned up top, FDM thermoplastics are typically used in the prototyping stage. The technique enables an engineer to quickly turn a virtually rendered component into a physical part, one that can be function-tested to see if it matches client specifications. Interestingly, advanced formulations are now sending the components into the end-use node of the process, which means 3D printed parts are now durable enough to fit tough application domains. The FDM machinery also works within tight constraints, the kind of high-tolerance values that result in geometrically accurate profiles. In short, the thermoplastic construct is an accurate rendering of the computer-modelled product.

The FDM polymer is selected according to its base chemical properties and how those properties work in tandem during the layering stage. The plastic scaffolding must layer precisely, melt on command, and solidify without sacrificing geometricity. Once fused, the layers are gone, leaving only a prototype or end-use product.