The most daunting challenge of automating assembly of very small products, such as hearing aids, is how to feed and manipulate tiny screws and other parts. These parts are so small that gravity becomes less dominant than other forces, such as van der Waals forces, surface tension and electrostatic energy. These forces cause tiny parts to stick to the gripper, creating problems with centering and alignment.

Researchers at the Technical University of Denmark in Lyngby have designed a gripper and an automatic screwdriver that overcome this challenge.

Led by Asta Gegeckaite, Ph.D., the researchers developed a mechanical gripper that can successfully pick up and release a small push button for a hearing aid. The researchers discovered that reducing the surface area of the gripper reduces the stiction effects and makes the gripping process more efficient.

The researchers also developed a fully automatic screwdriver that measures both torque and displacement during installation. “The screwdriver is both a handling device—it picks up, transports and releases the screw—and an assembly tool,” says Gegeckaite.

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