Products are becoming increasingly compact and lightweight, while are expected to convince in respect to functionality and sustainability. Metal is often used only where mechanical strength, electrical conductivity, or thermal management are indispensable. Most other functions are fulfilled by plastics, which can be processed economically through injection molding while offering a high degree of design freedom.

This development promotes advanced joining technologies. But mechanical fasteners require additional installation space, increase part count, and add assembly effort, whereas adhesive bonding often complicates recycling and repair processes.

Especially against the backdrop of “Right to repair” initiatives, joining solutions are in demand that combine long-term reliability with the option to be disassembled when required. The challenge is to achieve high process stability, material efficiency, and sustainability within a single joining concept.

Micro-mechanical interlocking
A promising answer is thermal direct joining which creates a direct bond between metal and plastic through a combination of micro-scale force-fit and form-fit mechanisms.

To achieve this, the metal surface is first roughened. The joining partners are then pressed together under a defined force while the metal component is heated inductively. The heat at the interface causes the plastic to melt locally and flow into the microscopic surface structures. Once cooled, the material solidifies and creates a highly robust, media-tight connection.

A key factor for industrial viability is the specially developed joining tooling. These tools enable highly concentrated heating within just a few hundred milliseconds, resulting in extremely short cycle times. At the same time, precise force-displacement control allows continuous monitoring and regulation of the process. This ensures consistent joint quality and the reproducibility required for large-scale manufacturing.