Rheology: Why It Matters in 3D Printing with Polymers

The concept of rheology refers to a branch of physics that studies fluids. Specifically, it examines how materials behave when they flow or deform, meaning how they respond to an applied force or stress. Although rheology applies to a wide range of scientific and technological fields, in the context of 3D printing, it becomes crucial for certain manufacturing technologies. It helps us understand and control how materials such as plastics and even hydrogels behave during the successive layering process.

This branch of physics was introduced by Eugene Bingham and became established as an independent discipline around 1930. Etymologically, the term rheology comes from the Greek rheo (“to flow”) and logos (“science”). In simple terms, rheology describes how materials deform and flow under different stress conditions. A material’s rheological behavior allows it to be classified according to how it reacts to applied forces. For example, elastic solids maintain their shape after deformation, while viscous fluids flow continuously when a force is applied. Finally, there are viscoelastic fluids, which combine properties of both elastic solids and viscous liquids, such as the polymers used in 3D printing.

A good understanding of rheology helps ensure the quality of 3D-printed parts.

The Importance of Rheology in 3D Printing

Rheology is essential in 3D printing because it describes how polymeric materials behave when deposited on the build platform, whether through extrusion or polymerization processes. Understanding the rheology of these plastics helps predict how they will perform during printing, which in turn is crucial for ensuring the quality and accuracy of the final part. This is because the rheological behavior of materials during printing directly affects several aspects of the process and the quality of the printed piece. Among the main reasons why rheology is fundamental in 3D printing are: