Press Riveting Joining Process
Joining of components by deforming a rivet fastener under high axial pressure
Press riveting is a mechanical joining process used to assemble fasteners such as rivet nuts and rivet studs to materials such as steel, aluminum, copper or magnesium.
This process creates a high-strength structural connection between the materials. The resulting joint is highly resistant to dynamic, static, and impact loads.
The press riveting is ideal for demanding applications. It is used when strong, reliable joints are required, such as:
- Joining components subjected to heavy loads or vibration.
- For lightweight components with highly durable joints.
- For heavy duty functional fasteners such as ball studs that need to withstand extreme side loads.
- Suitable for high-strength and ultra-high-strength sheet metal.
How Does Press Riveting Work?
During the press riveting process, the rivet collar is deformed to lock the fastener in place, creating a permanent joint.
First, a pilot hole with an embossing is made in the sheet metal. The clinch rivet fastener is inserted into the pilot hole. The rivet collar protrudes slightly from the bottom of the hole to allow room for deformation during the riveting process.
After the rivet fastener is inserted into the pilot hole, axial force is applied to deform the collar, which folds around the back of the material. Wedge-shaped ribs on the fastener bite into the material during the deformation, providing high torsional resistance. A special riveting die is used during installation, with either the collar or the die being oiled.
Once installed, the fastener becomes an integral part of the component. The joint is highly resistant to axial, torsional and lateral loads. For rivet nuts, it provides a secure internal thread for subsequent bolting, allowing modular and flexible designs.
Direct vs. Indirect Riveting
In direct press riveting, the rivet fastener is first fully inserted into the pilot hole. In a second step, the rivet collar is deformed with a riveting die.
In indirect press riveting, the deformation of the fastener occurs at the same time as it is positioned in the pilot hole. The rivet collar is pressed against a stationary die.
Advantages of Press Riveting Technology
Axial and torsional resistance: Self-clinching rivet fasteners create connections that can withstand high axial loads and torsional forces, making them suitable for dynamic applications.
Load capacity: Deformation of the rivet collar creates a strong bond that provides exceptional resistance to pull-out and push-out forces.
Durability: The resulting joint is durable and can withstand mechanical stress over time.
Versatile material compatibility: Works well with materials such as steel, aluminum, copper, magnesium and high-strength sheet metal.
Thin material joining: Effective on thin sheets without thinning or damaging the material.
Surface treatment friendly: Compatible with galvanized, painted, or coated materials without compromising the surface finish.
Lightweight components: Clinch rivet fasteners are ideal for applications where weight reduction is important, e.g. lightweight construction in the automotive industry.
Compact design: Clinch rivet fasteners require minimal installation space, making them suitable for tight or confined assembly areas.
Clean process: No harmful emissions or spatter because the process doesn't involve welding or adhesives.
Reduced risk of material degradation: No thermal stress or distortion, maintaining the structural integrity of materials.
The process produces tight joints that are resistant to liquid ingress, meeting the requirements of the automotive and other demanding industries.
Requirements for Press Riveting
Pilot Hole Preparation
Embossing plays a critical role in the success of a rivet fastener installation. It involves creating a slight indentation around the pilot hole on the underside of the sheet prior to inserting the rivet fastener. The embossing accommodates the folded rivet collar as the fastener deforms. In addition, the pilot hole must match the dimensions of the rivet fastener to ensure proper fit and secure installation.
Workpiece Material Properties
The workpiece material should ensure that the rivet fastener's underhead wedge ribs can effectively grip the material. In addition, the material thickness must be sufficient to allow the fastener to form a secure joint. Our clinch rivet nuts are suitable for material thicknesses from 0.7mm to 3.0mm and sheet metal tensile strengths from 600Mpa to approx. 800Mpa.
Case Study
Automated In-Die Assembly of Specialty Rivet Fasteners
A manufacturing challenge was to automate the assembly of a custom rivet fastener and bushing in a progressive die. The original plan was to assemble the rivet fastener as a separate operation using orbital riveting after press operation.
However, by optimizing the rivet area of the fastener, we were able to perform fully automatic assembly under the press. Now it was possible to place both fasteners in a single operation using our automation modules. Orbital riveting was no longer necessary.
Eliminating a secondary operation provided the following benefits:
- Lower production costs through a more efficient workflow
- Precision and repeatability due to in-die assembly
Our expertise in complex automated fastening solutions allowed us to execute this project successfully—delivering a cost-effective alternative that enhanced the overall manufacturing process of our customer.
Self-Clinching Rivet Nuts vs. Self-Clinching Nuts
Self-clinching rivet nuts provide superior strength and resistance to high axial, torsional, and push-out forces. This is because the deformation of the fastener creates a strong mechanical connection that resists these forces even better than self-clinching nuts.
Self-clinching rivet nuts are ideal for more demanding applications. Typically used in automotive and heavy industrial applications where vibration resistance and load-bearing strength are essential. They are suitable for sheet metal tensile strengths where conventional self-clinching nuts cannot be used.
On the other hand, self-clinching nuts are better suited for simpler installations. Therefore, the choice between the two depends on the specific requirements of the application, including material type, load requirements, and installation complexity.
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