Additive manufacturing is often associated with rigid prototypes and hard housings. Yet the technology has long reached a new dimension: the precise processing of flexible, elastic and rubber-like materials. Whether it concerns shock-absorbing soles, industrial seals or sensitive grippers in robotics – flexible 3D-printed components are revolutionising the way we design and functionalise products.

What makes a material “flexible”?

Unlike rigid plastics, flexible materials or elastomers are characterised by a low elastic modulus and high elongation at break. This means they can deform considerably under load and return almost completely to their original shape once the load is removed.

Two key metrics are decisive for selection:

  • Shore hardness: This indicates how soft or hard a material is. The Shore A scale covers soft to medium-hard elastomers (like a rubber band or a shoe sole), while Shore D is used for harder, semi-rigid plastics.
  • Elongation at break: This value describes how far a material can be stretched before it tears. High-performance materials often achieve values of 300 % to over 900 %.

Material diversity for every requirement

Today, a wide range of materials is available, each offering specific mechanical advantages:

  1. Thermoplastic Polyurethane (TPU): The industry standard for functional parts. It is extremely abrasion-resistant, durable and offers excellent vibration damping.
  2. Thermoplastic Elastomers (TPE): This group of materials is often softer than TPU and provides a particularly rubber-like feel, making them ideal for soft-touch grips and wearables.
  3. Liquid Silicone Rubber (LSR): Silicones are distinguished by the highest thermal stability (up to 200 °C), chemical resistance and outstanding biocompatibility. They are also sterilisable, making them predestined for medical technology.

The technology: The path to the perfect component

Depending on requirements for precision, isotropy and complexity, different printing processes are used:

  • Selective Laser Sintering (SLS): This process uses a laser to fuse powdered material (such as TPU powder) layer by layer. Since the surrounding powder acts as support, highly complex geometries can be manufactured without additional support structures.
  • Fused Deposition Modelling (FDM): Ideal for fast and cost-effective prototypes. Here, a flexible filament is extruded through a nozzle. A direct-drive extruder is important for feeding the soft material precisely.
  • Resin-based processes (SLA/DLP/PolyJet): These technologies offer the highest detail resolution and smoothest surfaces. The isotropy of the parts is particularly advantageous, as the chemical cross-linking between layers ensures uniform strength in all directions.

Design freedom: Lattice structures and integrated functions

A particular advantage of 3D printing is the ability to control the mechanical response of a component through its design.

Lattice structures make it possible to reduce weight drastically (often by up to 80 %) while maintaining stability. By adjusting the lattice geometry, stiffness can be varied locally – allowing a saddle or sole to provide soft cushioning in certain areas and rigid support in others.

Another milestone is the production of assemblies with moving parts in a single print run. Internal hinges, joints or snap-fit connections can be directly integrated, saving assembly time and reducing the risk of component failure.

Practical applications: Where flexibility counts

The application areas are diverse and constantly growing:

  • Robotics: Soft robotics uses elastic actuators and grippers that can safely handle delicate objects without damaging them.
  • Medical technology: Patient-specific orthoses, prosthetic liners or anatomical models for surgical planning benefit from the flexibility and precision fit.
  • Industry & automotive: Seals, bellows and vibration dampers are manufactured “on demand”, saving storage costs and significantly reducing time-to-market.

Conclusion

Additive manufacturing with flexible materials has long left the phase of pure prototyping and is today a strategic tool for serial production. The combination of material diversity, technological precision and boundless design freedom enables the creation of innovative products that would not be achievable with traditional methods. Those who incorporate flexibility into their manufacturing strategy secure a clear competitive advantage in an increasingly fast-moving industrial world.

Flexible materials in 3D printing open up entirely new design freedom – from lattice structures to integrated joints to patient-specific medical devices.

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