Fasteners are among the smallest components in modern technical systems – and perhaps for that very reason, among the most underestimated. Yet reliability is often not optional, but an essential requirement. Take the automotive industry as an example: complex assemblies are held together by thousands of screws and fastening elements. The failure of just one single screw in a critical position can compromise vehicle safety and performance and may even lead to costly recalls.
However, in many cases, it is not the fastener itself that makes the decisive difference, but rather the coating system behind it.
Functional coatings are no longer limited to corrosion protection. Today, they fulfill a wide range of additional tasks – from defined friction coefficients and wear protection to sealing and locking functions.
At the same time, requirements rarely occur in isolation. Modern fasteners often need to fulfill several of these functions simultaneously. This can be achieved through sophisticated coating systems consisting of multiple coordinated layers.
In practice, this means coatings are no longer just a downstream process step; they have become a key design parameter.
One major driver of this development is the increasing diversity of base materials. Aluminum, high-strength steels, and hybrid material combinations all require specifically adapted coating solutions.
New applications, especially in the field of e-mobility, are accelerating this trend even further. Sealing functions and electrical conductivity are becoming increasingly important, while lightweight construction introduces new material combinations that must be carefully evaluated regarding corrosion and material interactions.
At the same time, safety requirements have increased significantly. Fasteners are no longer expected only to connect components, but increasingly to perform additional functions – for example through threadlocking systems that prevent self-loosening under dynamic loads. In some cases, such requirements arise from completely unexpected reasons. In one project, a threadlocking solution became necessary not for technical reasons, but simply because a particularly valuable component was being stolen too frequently.
Another key factor in the development of coating systems is sustainability.
Requirements include PFAS-free formulations, water-based systems, and more energy-efficient processes. At the same time, these approaches often involve trade-offs: water-based coatings, for example, may require higher drying energy, while alternative chemistries can introduce additional additives or limitations in performance. These factors must be carefully balanced.
At the same time, increasing the service life of components themselves is a crucial sustainability factor. The longer a component operates reliably, the lower the maintenance effort, replacement demand, and overall resource consumption throughout its lifecycle. Suitable process solutions can also play a decisive role here.
One of the greatest challenges in coatings for fasteners is managing competing requirements.
A typical example is the combination of defined friction coefficients and threadlocking. Reproducible friction coefficients are essential for automated assembly processes. At the same time, the lubricants used for this purpose may negatively affect the adhesion of locking systems. Likewise, increased coating thickness intended to improve corrosion protection can adversely impact thread geometry and assembly behavior.
Solutions such as pre-applied threadlockers – for example based on precote® technology – are specifically designed to balance these requirements by combining defined friction properties with reliable locking performance.
These examples show that coating design always requires prioritization, but also a deep understanding of the overall system.
Despite their critical importance, coatings are often considered too late in the development process.
Coating experts are frequently involved only after problems have already occurred – such as functional failures, unexpected interactions, or deviations in assembly behavior.
Yet the comparatively low cost of a coating solution is often insignificant compared to the potential costs of failure. Even slightly higher investments in a suitable solution can prevent substantial issues during later operation.
The increasing complexity of requirements is driving a shift in how coatings are approached.
Instead of optimizing individual layers or processes in isolation, the focus is increasingly shifting toward the overall system – meaning the interaction of different technologies within a coordinated coating strategy.
This includes not only the coating itself, but also its interactions throughout the process chain, from pre-treatment and application to logistics and assembly.
Coatings for fasteners have evolved from a purely protective function into a central design element.
As requirements continue to grow – driven by demands for greater safety, sustainability, and new applications – early collaboration between design engineering and coating expertise is becoming increasingly essential.
So that even the smallest components can deliver their maximum impact.
Join Dr. Sebastian Thau, Global Director Functional Coatings, and Jochen Fezer, Global Director Electroplating at SurTec Group, as they discuss the critical role coatings play in ensuring the performance, reliability, and longevity of fastening components.
Podcast credit: Fastener Talk Podcast, produced by Fastener + Fixing Magazine. Interview conducted by Claire Aldridge.
