I. Introduction to Rivetless Joining Dies

1. Punch Point Joining is the core of the sheet metal stamping joining technology system. It uses a simple circular male die, pressed into the corresponding female die by the ZHOTE® pneumatic-hydraulic cylinder pressing device. Under further pressure, the sheet material on the male die side squeezes the sheet material on the female die side, causing it to "flow" and deform within the female die, forming the ZHOTE corrosion-resistant joint with no sharp edges or burrs. For sheets with painted or galvanized coatings, the paint or coating "flows" and deforms during the joining process without being damaged, so the joint does not affect the corrosion resistance of the sheet surface. ZHOTE® Punch Point Joining Dies are manufactured using state-of-the-art manufacturing and coating processes, ensuring an extremely long service life and the highest quality of the stamped joint.

2. Stepped offset dies are particularly suitable for difficult-to-access parts, such as C- and U-shaped sections, angled sheets, and other complex structures.

II. Loss-Free Joining Dies

1. ZHOTE® Punch Point Joining is an excellent method for permanently joining metal sheets. It is based on efficient cold forming, eliminating the need for additional connecting elements such as screws or rivets.

2. The connection is made using a male and female die with fixed or movable dies. This technology uses precise pressure to create a permanent, stable connection without degrading material properties, offering a robust alternative to welding. Therefore, punched dot joints are particularly suitable for joining sheets of varying thicknesses and types.

3. High process reliability and cost-effectiveness make punched dot joints a preferred choice in many industrial applications, as they eliminate the need for additional fasteners while ensuring a strong and durable connection.

3. Joining Sheet Metal

ZHOTE® punched dot joint technology is a joining process that complies with the DIN 8593 series of standards issued by the German Institute for Standardization. The metalworking industry uses this technology to join metal sheets of varying strengths and materials, including adhesive layers and intermediate layers. In industrial applications, this technology is suitable for individual sheets ranging from 0.1 mm to a total thickness of 20 mm, with a tensile strength of up to 800 N/mm². This low-cost, highly reliable, and environmentally friendly production process is a preferred alternative to welding, screwing, and riveting. The riveting tooling can be quickly and easily replaced, significantly improving production efficiency. The tooling can be used for single-point or multi-point applications. Special shapes are available upon request.

IV. Diverse and Flexible Applications

1. Secure Connections

ZHOTE® Punched Dot Connections offer high flexibility, enabling secure connections of various sheet grades, surfaces, and thicknesses. Furthermore, adhesives or other intermediate layers can be integrated into the process, enabling a wide range of applications.

2. Unlimited Material Combinations

ZHOTE® Punched Dot Connections can connect a wide variety of material combinations, including steel, aluminum, stainless steel, and copper. Continuous improvements to the tooling ensure a long service life and reliable connection performance.

3. Excellent Electrical Conductivity

ZHOTE® Connections ensure excellent electrical conductivity, making them particularly suitable for electrical components. They do not alter the material properties and produce stable, push-to-connect connections with high joint strength.

V. Applications of Rivetless Connection Dies

1. Automotive Manufacturing

Used for connecting components such as bumpers, exhaust pipes, engine covers, doors, instrument panels, and brake covers, especially for non-load-bearing parts (such as doors and trunk lids).

2. Home Appliances

Applied for the assembly of components such as washing machine housings, refrigerator doors, and air conditioner outer casings, as seen in products from brands like Little Swan and Midea. ‌2

3. Industrial Equipment

Suitable for fastening metal structures such as chassis and cabinets, elevator platforms, and busbars. ‌1

4. Electronic Products

Used for securing precision components such as computer housings and copier chassis. ‌1

This technology offers advantages such as strong surface coating compatibility (connection requires no treatment), low energy consumption, and environmental friendliness. However, caution should be exercised when using materials with significantly different thicknesses.

VI. Rivetless Connection Testing

1. AC servo direct-drive tensile testing equipment enables variable speed and stroke, effectively improving efficiency. When the punch reaches the desired position, it begins reverse motion. In the rivetless joining process, an S-shaped mechanical lock is primarily created on the cross-section. During plastic forming, die geometry is a significant factor, and the material properties themselves also influence joint quality. The S-shape is essentially formed when the sheet base thickness reaches 40% of the combined thickness. Furthermore, the primary quantitative criterion for evaluating joint quality is joint strength. Generally, this equipment can provide a punching force of 10 to 150 kN. When testing the mechanical properties of Al6061 sheets, the joints are typically circular or square in shape. This experiment primarily used circular joints. A paper by Y. Abealet et al. explains that the fracture of high-strength steel is primarily due to poor toughness and deformation at the punch corners, and proposes that joint strength is a factor in determining riveting quality.

2. To facilitate joint strength testing, sheets are generally arranged horizontally or vertically during riveting. Vertical sheet arrangement is used for tensile strength measurements, and a dedicated fixture is designed for this purpose. Shear strength testing of joints is performed horizontally, also requiring a dedicated fixture.