Primer-free bonding of composite structures for unmanned systems
Industry: Unmanned aerial and ground systems, composite structures
Technology: Atmospheric plasma (PlasmaTEC-X), vacuum plasma (VacuTEC), surface energy verification
When a composite airframe moves from hand-built prototype to series production, manual surface preparation quickly becomes the bottleneck and the biggest source of bond variation. Integrating atmospheric plasma directly into the robot cell activates every bonding surface the same way, without primers or solvents, and with process data that supports qualification.
The challenge
Unmanned systems depend on lightweight structures. Carbon fiber and glass fiber laminates, thermoplastic composites and hybrid metal-composite assemblies are joined with structural adhesives, because bonding saves weight and spreads loads better than fasteners.
The problem is the surface. Composites leave the mold with low surface energy, residues of release agents and contamination from handling. Adhesives cannot wet such a surface properly, and the joint fails at the interface rather than in the adhesive itself.
At prototype scale, skilled technicians solve this by hand: abrading, solvent wiping and applying a primer. When volumes rise, more shifts, new operators and new sites enter the process. Bond quality starts to depend on who did the work, and on which day.
Why conventional preparation falls short
- Manual abrasion is operator-dependent and can damage surface fibers or leave dust in the bond line.
- Solvent wiping can spread contamination instead of removing it and adds handling of hazardous substances.
- Primers add process steps, flash-off and cure time, shelf-life control and chemicals that face growing regulatory pressure.
- None of these steps is easy to document per part, which makes qualification and traceability harder.
The solution
Atmospheric plasma treats the bond area immediately before the adhesive is applied. The plasma removes organic contaminants and adds polar functional groups to the surface. Surface energy rises, the adhesive wets the substrate fully, and the bond can form chemically as well as mechanically.
A PlasmaTEC-X nozzle mounted on the robot follows the bond line with a fixed distance and speed. Only the area that needs activation is treated, and the robot does it identically on every part.
For smaller components, inserts or parts with cavities and complex geometry, VacuTEC vacuum plasma treats the entire part in a batch. This includes recesses and back sides that a nozzle cannot reach.
Because an activated surface should be bonded within a defined time window, inline integration is an advantage in itself. Treatment and adhesive dispensing happen in the same cell, so the window is controlled by the process rather than by planning.
How it fits into production
- Trials on real parts. The customer’s own laminates and adhesive are tested in Tantec’s laboratory to find the right treatment and confirm the effect.
- Process window. Distance, speed and treatment intensity are defined for each bond line.
- Integration. The plasma unit is built into the robot cell or line, with signals to the line control.
- Verification. Surface energy is checked with dyne testing during setup and as routine control, and the treatment process is monitored so deviations are caught before parts are bonded.
Why Tantec
- Both atmospheric and vacuum plasma in-house. The choice depends on the part, not on what the supplier happens to sell.
- Robot-ready systems designed for treating complex 3D geometries inline.
- Laboratory testing on the customer’s own materials before any investment is made.
- Verification tools for surface energy and process monitoring, which support documentation and qualification.
- Standard machines and custom-built solutions from a European manufacturer with decades of experience in surface treatment.
Is this your challenge?
If your bonded composite parts fail at the interface, or your surface preparation will not scale with your production, send us sample parts. We will test them in our laboratory and show you what a dry, repeatable plasma process can do for your bond line.