3D printing is now commonly used in many sectors, including the field of spring manufacturing. One interesting application is the 3D printing of extension springs, which are built to store energy and keep force between two objects. Learning to 3D print extension springs requires understanding how different materials like metals and plastics affect the spring's performance. In this article, you'll find a detailed guide on calculating deflection in plastic extension springs, weighing the benefits and drawbacks of plastic and metal springs, and creating a practical spring. For instance, there was a case where engineers faced excessive deflection in a spring. Addressing this issue required combining a traditional metal spring with a 3D printed plastic one, resulting in a unique hybrid model. Various factors in this process, such as your 3D printer, material choice, and design, all play a role in the final product - the manufactured extension spring.

Calculating Deflection in Plastic Extension Springs

Deflection refers to the extent of deformation a spring undergoes when subjected to load. This is a key parameter to consider when 3D printing plastic extension springs. Two factors influence this: the properties of the material and the physical dimensions of the spring.

The rigidity or flexibility of the material, represented by Young's Modulus, affects deflection. For instance, ABS plastic, known for its relatively high Young's Modulus, yields a spring that shows less deflection under load compared to a spring made from TPU, a material noted for its flexibility.

The physical dimensions, like diameter or wire size of the spring, also exert influence on deflection. Springs with larger dimensions tend to show less deflection as they distribute the load over a wider area. Conversely, larger dimensions may heighten the spring's stiffness, potentially restricting extension under load. Furthermore, springs with more active coils can exhibit increased deflection due to added flexibility. These factors should be considered during the design process.

Accounting for these factors while modeling your spring can assist with accurate estimations of deflection. This in turn aids in producing springs that perform in line with expectations.

Differences Between Metal and Plastic Springs

Designing the Extension Spring Features and Dimensions

For 3D printing of plastic extension springs, consider diameter, length, spring index, and coil count. These factors establish the spring's mechanical properties.

The diameter and length must be compatible with the part the spring will connect with. In relation to a 3D printed drone part that requires an extension spring, the spring length and diameter must respect the given dimensions of the part for effective operation.

The spring index, defined as the ratio of the coil diameter to the wire diameter, contributes to the lifespan and resilience of the spring. Although it may appear contrary, a lower spring index produces a stronger spring. The inverse relationship in the spring index calculation means a lower ratio indicates a thicker wire, resulting in greater stress-resistance.

The coil count affects the spring's load endurance, namely, the amount of force it can resist before permanently deforming. Springs with more coils can tolerate larger loads. However, increasing the coil count raises material use, which can affect the spring's overall weight - a key factor for weight-sensitive applications like aerospace. The task here is to find an equilibrium between load capacity and weight.

Paying attention to these four dimensions aids in producing a 3D printed spring that aligns with specific requirements. Implementing these principles based on the functional needs of the application eases the process of designing 3D printed extension springs.


3D printing enables the creation of extension springs that extends beyond traditional manufacturing methods. This process allows for customization of springs for special applications and the manufacture of springs that resist corrosion. Key areas of focus include estimating deflection accurately, getting a grasp on how plastic springs perform compared to metal ones, and proper sizing and shaping of spring features. With a thorough understanding of these aspects, spring designs can be tailored to suit specific applications, therefore simplifying the selection process.