Bionic Manufacturing

Additive manufacturing technique to produce biomimetic plastic components and products using the example of a cantilever chair #

© Fraunhofer UMSICHT, Entwurf Folkwang Universität der Künste

SLS cantilever chair

Cantilever made from thermoplastic material produced by means of selective laser sintering (SLS).

© Fraunhofer UMSICHT

Tension rod

Sintered tension rod made from 2 material components (TPU).

Project aims#

The project BIONIC MANUFACTURING pursued the development of an additive manufacturing technique to produce components according to biological design and structuring principles using the example of a cantilever chair. Within the scope of the project, both selective laser sintering (SLS) and mask sintering (SMS) were to be further developed into a production technique for biologically inspired components.

With a load-bearing geometry and a finely structured, locally varying composition of the material, the components should follow biological principles in terms of their outer shape and in their inner material structure. The overall aim of the project was to develop a technology that has the long-term potential to become a basic technology for biomimetics. In the future, this should make it possible to manufacture biomimetic plastic components and products in both the design and technical fields and supplement the process paths of biomimetic optimization methods.

Benefits#

A fundamental gain in technical knowledge is pursued in biomimetics. Knowledge from the observation and analysis of biological models can ultimately be transferred to technical systems. As a rule, biological organisms achieve their amazing performance with a very limited selection of different materials (opportunism principle). The key to this lies in the intricate, load-appropriate and often hierarchical structuring of biological materials, structures, and constructions. This cross-scale structuring is made possible by means of a  bottom-up formation principle. With classic processing, thermoplastics do not achieve such an ordered, intricate structuring as nature does due to the exclusively stochastic distribution of fillers, short fibers or pores.

SLS for biomimetic production technique

The 3D printing technique selective laser sintering (SLS) uses a laser to produce spatial structures from a powdery starting material. The component is created by locally melting the individual plastic particles in layers and joining them together. Although the components are assembled from the smallest particles in a controlled manner, SLS has so far only produced components from homogeneous plastics or composites.

By limiting SLS to homogeneous materials, a great deal of potential is wasted. BIONIC MANUFACTURING, on the other hand, has tapped into this potential by extending it to multi-component SLS, thus enabling the transfer of material and design concepts from nature. So far, there have been neither convincing systematic investigations nor well-functioning technical implementations.

Result#

In the course of the project, a cantilever chair was developed and optimized and a functioning FEM simulation was developed. In addition, the biomimetic design and the grid structure of the chair were improved by using a material, and a printable multi-material was developed. The researchers at Fraunhofer UMSICHT also built a test rig for material development and the further development of machine technology.

Prototype and SLS process

In the project, biomimetic design and optimization principles were applied to different length scales (hierarchies): In the macroscopic (visible) development line, optimized lattice structures were created for a cantilever chair. In the microscopic (invisible) development line, SLS was further developed so that components with locally variable or graded material characteristics could be generated. To this end, the local variation of the composition and the local activation of the polymer particles as well as the integration of a 2-component dosing technique into the previous SLS technique were investigated. During the local activation of the polymer powders, reactive or orientable additives were incorporated into the polymers. Some experiments were successfully carried out, others may require alternative approaches in the future.

Advantages thanks to a novel approach

Compared to conventional solutions, the new process can achieve material and weight savings as well as cost reductions through optimized structuring. The possibility of manufacturing customer-specific and demand-oriented products also has the potential to replace inexpensive disposable products with durable, individual goods.

Project consortium#

  • Fraunhofer UMSICHT (Development of alternative SLS materials + construction of the first 3D printer prototype)
  • Folkwang University of the Arts (design of the cantilever chair)
  • Fraunhofer Institute for Mechanics of Materials IWM (biomimetic design of the chair)
  • Sintermask GmbH (development of printing techniques)
  • rapid product manufacturing GmbH (production of all specimens for material tests)
  • Athentics GmbH (strategic design of the chair)

Funding
Duration: June 2009 to May 2012
Funding code: 01RB0708B
Website: www.bmbf.de