Volker Krebs: 3D-Printed Nut

Application Overview

• What was needed: An alternative to metal ball screw nuts that can be produced independently using 3D printing
• Requirements: 100% self-lubricating and maintenance-free, quiet running, simple manufacture, smooth running, backlash-free
• Material used: iglide® i190-PF filament
• Success for the customer: With the design, there was no other way to achieve the set goal. The parameters were given and the end product had to work. Optimizing the contact area was key to reducing friction. The surface hardening of the threads also reduced friction. After several printing attempts, the print quality could be improved.

Volker Krebs from VKC Services Ltd in Canada needed a threaded nut. Metallic ball screw nuts are too heavy and also require regular maintenance and lubrication. In a 6DoF (6 directions of force) simulator, the noise of the ball screw can be very annoying over time. The simulators are used indoors and therefore work in a constant temperature environment.

The biggest challenge was finding the right tolerances to get a smooth-running and backlash-free screw drive. The ball screw bearing converts rotation into linear motion. Use in an actuator requires that they can withstand linear acceleration forces up to 3g under various load conditions. The average engine speed is 800-1200 rpm, but can also go up to 3000 rpm. The load per drive is about 1500N.

Volker Krebs has designed a replacement for a ball screw nut. The material for this is the iglide i190. By using igus linear bearings and now also iglide i190 3D printed polymer nuts, the simulator becomes a really mechanically quiet simulator. The actuator's inner slide has also been integrated into the nut design for easier maintenance. When designing, there was no other way to achieve the set goal. The parameters were given and the end product had to work. Optimizing the contact area was key to reducing friction. The surface hardening of the threads also reduced friction.