Customized Robot Gripper Designs using 3D Printing with Silicone

Soft Robotics – a Trending Field

Soft robotics is a subfield of robotics and incorporates the use of soft materials. For example, a robot with knee joints that bend or elastic grippers on a hand used for grasping. Soft robotics deals with creating robots from materials that mimic living organisms in terms of how they move and adapt to their environment. Soft robotics are flexible, light weight and can adjust to many tasks, while improving safety when working alongside of humans. This allows for them to be of great use in manufacturing, the food industry and medical settings.

ACEO® 3D Printing with Silicones

In order to manufacture highly functional parts like grippers, 3D printing is the method of choice as it provides freedom of design. ACEO® ‘s unique drop-on-demand technology enables unprecedented product designs and complex geometries to be produced, while retaining the outstanding properties of silicone, such as heat and UV resistance or biocompatibility.

WACKER’s ACEO® introduced the first industrial 3D printer for silicones, which was developed by WACKER engineers (Photo: ACEO®; Wacker Chemie AG).

For Soft Robotics, ACEO® ‘s technology provides a unique combination of design freedom, soft materials and small series. This allows the additive manufacturing of pneumatic silicone actuators that exhibit unprecedented programmable, bioinspired architectures and motions.

Silicone Elastomers – A Versatile High-Tech Material

Silicone elastomers have been produced for about 70 years. This modern high-tech material is known for its elasticity and durability. Silicone Elastomers are inorganic synthetic rubbers that offer a unique combination of chemical and mechanical properties such as temperature- and UV stability, media resistance, tensile strength and compression set. These properties are maintained throughout the ACEO® printing process so the performance of 3D-printed silicone parts, are comparable with silicone parts that are manufactured using conventional processes such as injection molding or rapid prototyping.

3D-printed silicone gripper in gray color holding an object (Photo: ACEO®; Wacker Chemie AG)

ACEO® product example, pneumatic gripper, robot finger (Photo: ACEO®; Wacker Chemie AG)

Customer Testimony – Formhand

New technologies demand innovative solutions. Holger Kunz is a founding member of the German Startup Formhand – a spinoff project from the Technical University of Braunschweig. Together with co-founders Kirsten Büchler and Christian Löchte he developed a universal gripper for multi-purpose applications across industries.

Formhand develops grippers that are used in automation technology. Throughout these automated processes, parts need to be moved by robots. An example: the left and right car wing of a car are almost identical components except for the fact that they are mirrored. In manufacturing, these are two different parts that need two different robot hands, or grippers, for the same process step. Basically, each part needs its own gripper.

The Formhand approach is to reduce complexity with a gripper which adapts to different materials or surfaces. This means that customers get a product that is more intelligent and can help optimize their automated processes.

It was an idea as simple as it was brilliant. “Any child understands the principle from home: if you suck up a ball with a vacuum cleaner, you can move the ball from point A to point B. The main idea behind Formhand is to add a granulate-filled pad in front of the ‘vacuum cleaner’: the vacuum changes the shape of the pad, molding it to any geometry you like,” Kunz explains.

The development started with a gripper that consisted of a pillow with a textile surface that contains granulates. This pillow creates a vacuum and adapts to the surface of the part it needs to handle. We needed to explore elastic materials for the prototypes. ACEO® provided the opportunity to do test prints in the Open Print Lab and where they could provide expert help with prototypes.

During this Open Print Lab session, a first blue cap – the “glove” – was printed out. Kunz and the ACEO® team inspect the thin-walled piece from all sides and confer. “Here you can see another strength – and an important application – of 3D printing in action: prototyping. It allows companies to create unique components quickly and at low cost”.

After these developments, Kunz reported “Now we have a customer who’s ordered a very small Formhand that has to meet highly precise grasping specifications. What we need are basically gloves like the ones surgeons wear. Silicone is the logical solution.”

Formhand developed a universal gripper for multi-purpose applications, 3D printed by ACEO® (Photo: FORMHAND)

ACEO® drop-on-demand technology

The ACEO® technology is based on a “drop on demand” principle. The print head deposits single silicone voxels on a building platform, which flow together smoothly, forming a homogeneous surface. After printing a layer, the curing is activated by a UV light. This way, a three-dimensional object is built up layer by layer. In order to realize complex structures, overhangs and cavities, a support material is printed during the same process. The support material, which is environmentally safe, is easily and quickly washed out with water. Subsequently, the part is post-cured to achieve the final mechanical properties.