Neatly knitted

Article of 28 April 2017 

Neatly knitted: 3D knitting production technology

Whoever thinks that knitting is old-fashioned is wide of the mark. More and more products are being made out of a variety of materials using 3D knitting – and in very different industries. Flexibility and stability combined with an effective and environmentally friendly production process are just a few benefits of the innovative technology.

Office chairs, safety gloves, bandages and sports shoes have one thing in common: they are produced with an innovative technology, 3D knitting. Which type of yarn is used varies depending on the area of application. It is possible to knit with metal or glass fibres as well as textile fibres. In future, technical knitted fabrics are expected to be increasingly used as materials for aeroplanes and cars or for building bridges.

The major advantage of the production technology is that both rigid and flexible areas can be incorporated within a part. In this way, for example, a shoe can adapt better to the movement of the foot than standard footwear. At the same time, the stiff zones in the knitted structure give the foot stability in places where it is needed. Knitting with a lightweight yarn compound also gives the shoe a low weight.

Stitch by stitch an efficient and environmentally friendly production method

The technology also proves itself from an environmental perspective: no waste products are created and, in the case of some knitting techniques, further steps in the production process become superfluous, for example sewing parts together. As the fibres of the textile shaft are already woven with each other, the knitted barefoot shoe does not need any seams, for example.

Traditional handicraft keeps up with the times so that it can meet the requirements of the modern market
Traditional handicraft keeps up with the times so that it can meet the requirements of the modern market

Taking a close look at animal muscles

A 3D knitted textile fabric also provides the right structure in the Festo BionicMotionRobot. When it came to developing the bionic robot arm, the engineers looked closely at the muscle fibre of an octopus’ tentacle. In the tentacle, the muscle cords run in several layers and in different directions. The interaction of radial, diagonal and longitudinal fibres allows the octopus to control its tentacles in a targeted manner. Inside the pneumatic robot arm, there is a 3D textile fabric that is based on this natural role model.

The muscle fibres in an octopus’ tentacle run in different directions
The muscle fibres in an octopus’ tentacle run in different directions

3D knitting technology in the Festo BionicMotionRobot

The knitted fabric surrounds small, elastic air chambers along the robot arm. The chambers are activated by compressed air and can fold together or expand like an accordion, thus moving the arm. At this point, the textile covering of the air chambers comes into play: based on the muscle fibres of the octopus, the elastic and rigid strands run around the chambers in a special pattern. By this means, the textile structure determines at which places the robot arm extends and thus develops power, and at which ones extension is prevented. In this way, the BionicMotionRobot can move both powerfully and quickly as well as softly and precisely.

A 3D textile knitted fabric surrounds the air chambers
A 3D textile knitted fabric surrounds the air chambers

The natural forms of movement mean that the BionicMotionRobot can be used for various tasks and work hand in hand with humans without danger. You can find out more about how the pneumatic robot arm works and its potential uses in the video: