2024-4-20 • Ryan

Understanding Material Creep in 3D Printing

Introduction

Material creep refers to a materials tendency to deform or stretch in dimension over time, whether with a force applied or under heightened temperatures or both. Material creep is typically measured as elongation (ε) which is the difference in a specified dimension measurement from the measurement at rest. Material creep is very relevant in 3D printing when producing functional parts that require a certain structural stiffness or dimensional stability under load.

Understanding material properties is very important, as material properties quickly dictate design decisions. Recently, a study published in the Strojniški vestnik - Journal of Mechanical Engineering shed light on the property of material creep for 3D printed parts. Let's take a closer look at the findings and what they mean.

The study, led by Oguz Dogan and his team, examined material creep of various plastics commonly used in 3D printing, such as; PLA, ABS, TPLA, CPE, Nylon, and PC — to different thermal and loading conditions. They used the ASTM D2990-17 standard for producing the test specimens and results.

Key Findings

  • Material elongation increased when the temperature or load increased for all plastics.
  • Load has a more significant impact on elongation than temperature.
  • PLA exhibits the worst creep resistance, suggesting parts made from PLA should be used at room temperature with minimal loading.
  • ABS and ASA are suitable for moderate loads and temperatures but not recommended for high loads and temperatures.
  • Nylon experiences significant elongation at temperature or load but does not rupture (yield) under the tested conditions.
  • PC demonstrates the highest resistance to creep among the tested materials, making it suitable for high loads and temperatures.

Implications and Recommendations

What do these findings mean? PC is clearly undisputed among PLA, ABS/ASA and Nylon when it comes to dimensional stability under high load or temperature. Nylon evidently is not a suitable material for applications that require dimensional stability. ABS/ASA is a good middle-ground choice when it comes to chosing a material for most medium to high load applications. PLA while very printable still remains the choice for display only models or prototypes.

As we continue to push the boundaries of 3D printing technology, studies like these are incredibly valuable, informing best practices and driving innovation. By incorporating the insights gleaned from Dogan's research into our design, we can elevate the quality and performance of our prints.

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