Press-Fit Combination of Rivet Nut and Washer/Spacer

The nut-washer combination is particularly suitable

• For tightly toleranced distances between bolted components
• As a frame rail/crash box combination
• As connecting thread for large sheet thicknesses where no beading is possible
• For large sheet thicknesses where no protrusion is possible
• As form closure or anti-twist lock for attachments
• as a chemical insulator between steel and aluminum

• As form closure to counteract displacement forces
• For battery-carrier connection
• As stop surface
• As spacer for tightly toleranced distances
• As sheet reinforcement for thin sheets

The A240 assembly system for robots and the A220 operator workstation can be used to insert rivet nuts (as well as self-clinching nuts) and ribbed washers into workpieces.

A robot or operator places a component on the washer, which is already on the die, and starts the pressing process. Then, the plunger delivers the nut and applies a force stroke, connecting the nut and washer to the component in a single-setting operation. The component is held by the robot or operator throughout the entire process. Nuts and washers are fed in via the corresponding feeding systems.

A special gripper mechanism transfers the washer. The feeding system delivers a washer when the corresponding sensor is available. Then, a slide moves the washer to the removal position, where it arrives in the correct alignment. When requested, the gripper picks up the washer and places it on the die. The gripper then returns to its starting position. Only then is a new washer moved to the removal position.

In this project, the objective was to design a custom solution that would combine a self-clinching rivet nut and a spacer bushing, allowing both components to be installed automatically within a single production step. The challenge was that the installation had to be done in a single die station positioned at a 90-degree angle to the stamping direction and within a very confined workspace.

To achieve this, we designed the rivet nut and spacer bushing to integrate seamlessly into the transfer tool process. A comprehensive series of application tests was conducted to confirm process reliability.

The fasteners were developed simultaneously with the automation system design. This approach ensured that any potential feasibility issues were identified and resolved early in the project.

Thanks to our in-depth expertise in fastening technology and automated assembly, we were able to deliver a solution that met the technical requirements and ensured consistent, efficient production.

1. Blind Rivet Nut

Limited strength and low pull-through

• due to lower material hardness of a blind rivet nut
• due to less loadable small rivet bulge
• because there is no preload between the metal sheets
• as there is a risk of setting behavior within the connection

2. Self-Clinching Nut and Washer Combination

High strength and high pull-through

• due to highly tempered nut
• due to larger and higher nut dimensions
• because regular preload is built up between the metal sheets
• because of higher dimensions, no setting behavior within the connection

3. Self-Clinching Nut Without Washer

• Also used as standalone fastener with the same strength advantages