The joining technology used in a product determines whether it can be repaired, reused, or cleanly recycled at the end of its life - or whether it ends up as waste. That decision isn't made at the recycling facility. It's made at the design table.
With the [1], this issue has moved to the center of industrial product development. The regulation entered into force on July 18, 2024 and sets new, significantly stricter requirements for the entire product lifecycle - from raw material extraction to end-of-life disposal. For design engineers and production managers, this means one thing: the choice of joining technology is no longer a purely mechanical question.
Why Joining Technology Determines Circularity
EU Ecodesign Regulation 2024/1781 applies - unlike its predecessor - to virtually all physical products, not just energy-related equipment. [2] It establishes requirements to make products more durable, repairable, reusable, and recyclable.
The core problem: many products don't fail due to a lack of recycling infrastructure - they fail because of how they were designed. [3] Joints should be designed so that they can be disassembled non-destructively even after the intended product service life - and should be clearly identifiable and easily accessible.
This is precisely where threaded fasteners hold a structural advantage.
Screws vs. Adhesives, Welding, and Rivets: An Objective Comparison
| Kriterium | Schrauben | Kleben | Schweißen | Nieten |
|---|---|---|---|---|
| Lösbarkeit | ✅ Zerstörungsfrei lösbar | ⚠️ Nur mit Spezialverfahren / DIN/TS 54405 | ❌ Nicht zerstörungsfrei lösbar | ❌ Nur durch Bohren/Schleifen lösbar |
| Demontageaufwand | Gering bis mittel | Hoch (thermisch, chemisch) | Sehr hoch (Trennschnitt) | Hoch (mechanisch) |
| Wiederverwendbarkeit der Fügeteile | ✅ Hoch | ⚠️ Eingeschränkt | ❌ Gering (Wärmeeinflusszone) | ⚠️ Eingeschränkt |
| Sortenreine Materialtrennung | ✅ Gut möglich | ⚠️ Klebstoffrückstände problematisch | ⚠️ Mischgefüge möglich | ⚠️ Niete oft Fremdmaterial |
| Recyclingfähigkeit | ✅ Hoch | ⚠️ Eingeschränkt | ⚠️ Eingeschränkt | ⚠️ Eingeschränkt |
| Reparierbarkeit | ✅ Sehr gut | ⚠️ Eingeschränkt | ❌ Aufwendig | ⚠️ Eingeschränkt |
| Leichtbau-Eignung | ⚠️ Mittel | ✅ Gut (flächige Lastverteilung) | ✅ Gut | ✅ Gut |
| Dokumentierbarkeit des Fügevorgangs | ✅ Vollständig (Drehmoment, Winkel) | ⚠️ Eingeschränkt | ⚠️ Eingeschränkt | ⚠️ Eingeschränkt |
The decisive difference lies in reversibility. [4] What is often cited as the biggest drawback of threaded fasteners - the fact that they can be undone - is simultaneously their greatest advantage for the circular economy.
Non-releasable joints such as adhesive bonds can prevent clean material separation and stand in the way of recyclability. [5] Many materials joined this way are sent to energy recovery and exit the material cycle entirely, even though their individual components could have been reclaimed.
This doesn't mean adhesives or welding are inherently wrong. These joining methods should, however, only be used with materials that are suited for recycling, in order to reduce the separation and sorting processes required for material recovery. [3]
The Four Levers of the Circular Economy - and How Fasteners Serve Each One
1. Disassembly
A releasable joint is the fundamental prerequisite for every circular process. [6] Instead of permanent connections such as adhesives and composite materials, reversible joining technologies like screws, bolts, and clamps enable straightforward disassembly.
For the automation of disassembly processes, corroded or otherwise non-releasable threaded joints - as well as permanent adhesive bonds - present specific practical challenges. [7] The takeaway: not every screw is automatically circular-economy-compatible. Corrosion protection, accessibility, and standardization of drive types all play an equally important role.
2. Repair
The EU Right to Repair Directive (EU) 2024/1799 entered into force in July 2024; member states must transpose it into national law by July 31, 2026. Only after that will consumers gain the right to repair for certain product categories at reasonable prices. [8]
Repair requires disassembly. Connecting components with screws enables the targeted replacement of individual parts - without damaging the overall product. That is the direct contribution of joining technology to repairability.
3. Reuse
Components that can be disassembled non-destructively retain their material value. [9] The selection of a fastener has a direct impact on the ease of disassembly, the reusability of materials, and the longevity of assemblies.
4. Recycling
Clean material separation is the prerequisite for high-quality recycling. Threaded fasteners enable the clean separation of different materials - aluminum from steel, plastic from metal - without contamination from adhesive residues or the mixed microstructures left by welds.
The circular economy doesn't start at the recycling facility — it starts in the engineering department. Designing for releasable connections today reduces the effort required for disassembly, repair, and material recovery tomorrow — while simultaneously meeting the requirements of the EU Ecodesign Regulation.
The Regulatory Framework: What the EU Specifically Requires
EU Ecodesign Regulation 2024/1781 defines in Article 5 the types of ecodesign requirements and refers to Annex I for the specific product parameters - including repairability, recycled content, and recyclability; which requirements apply in practice is determined on a product-group basis through delegated acts. [10]
In concrete terms, this means for manufacturers:
- Design for repairability: Components must be installed in a way that makes them easier to replace. [8]
- Spare parts obligation: For certain product categories, spare parts and repair information must be made available for seven years. [11]
- Digital Product Passport (DPP): From 2027, the Digital Product Passport will be mandatory for certain product categories in the EU, including industrial and vehicle batteries. [12] It contains information on materials, repairability, and recyclability.
The DPP also fundamentally changes the requirements for assembly documentation: anyone who captures and archives bolting data without gaps is already building the data foundation for tomorrow's Digital Product Passport today.
Precise Bolting: Why "Just Tighten It Down" Isn't Good Enough
Releasability alone is not enough. A threaded joint that cannot be reproducibly re-tightened after disassembly loses its circular economy advantage.
This is an often-underestimated problem: [13] Variations in friction coefficients and the torque scatter of the tightening tool have a significant influence on the resulting clamp load. Even with high torque repeatability, variations in the resulting clamp load of 50% or more can occur when torque alone is used as the control parameter.
The combination of torque and angle measurement addresses this dependency directly. [14] The clamp load results from the interplay of torque, angle of rotation, and the friction values of the surfaces involved - these parameters must be continuously monitored.
Documented Re-tightening as a Quality Benchmark
[15] Every bolting result - whether OK or not OK - should be documented, including all torque and angle values. This applies especially to re-tightening operations following repairs or component replacement.
[14] Comprehensive documentation and archiving of all data is essential in order to provide the necessary evidence in the event of warranty or liability claims.
For the circular economy, this means: a fastener that is reinstalled after disassembly must be tightened to the same parameters as the first time - and that process must be verifiable.
What This Means for Your Assembly Operation: A Decision Framework
GWK Tools: Precision That Closes the Loop
Reversible fasteners only deliver their full circular economy advantage when the bolting process - both at initial assembly and during re-tightening - is precise, reproducible, and fully documented.
The QUANTEC MCS® analysis tool from GWK enables complete analysis of the threaded joint through its reference-point-free angle measurement - from head seating to final torque. It provides the data foundation to validate and document bolting processes for repair and rework scenarios.
The OPERATOR® production tool, with its modular interchangeable-square system, is designed precisely for these requirements: flexibly deployable on assembly lines, rework stations, and in contingency strategies, with Wi-Fi data transfer for seamless process documentation. Individually replaceable components keep follow-on costs low - a principle that applies the circular economy logic to the tool itself.
For quality assurance following repairs and re-tightening operations, the Q-CHECK® - as a QA and audit tool - provides the capability to perform residual torque measurements and process capability studies in accordance with VDI/VDE 2645-3, thereby demonstrating that the joint has returned to its specified parameters after disassembly.
Conclusion: Joining Technology as a Strategic Decision
The choice between screws, adhesives, welding, and rivets is no longer a purely technical question. It is a strategic decision with direct implications for repairability, reusability, recyclability - and for compliance with a growing EU regulatory framework.
Reversible threaded fasteners are not a compromise - they are an enabler. They make disassembly, repair, reuse, and clean material recycling possible. The prerequisite is that bolting is carried out precisely, reproducibly, and with complete documentation - at initial assembly and at every subsequent re-tightening.
Those who invest today in precise bolting technology and comprehensive documentation are not only preparing for the requirements of the EU Ecodesign Regulation. They are building the technical foundation for an assembly process that genuinely closes the loop.
Accuracy by GWK.
