Threadlockers are essential to ensure the reliability and safety of your screw connections. Whether in technical devices, furniture, vehicles, or industrial plants – they ensure that your connections remain firm and secure even under vibrations, dynamic loads, or other influences. In this article, you will learn how to select and apply the right screw lockings to optimally protect your applications.

What are Threadlockers?

Threadlockers are specialised products that prevent screw connections from coming loose unintentionally. They increase the safety and longevity of connections that are exposed to vibrations or other stresses. There are various types:

• Settling protection: Compensates for the settling behaviour of the material and maintains the pre-tensioning force (e.g. tension discs, disc springs).​
• Anti-loosening device: Prevents mechanical loosening through additional components such as locking nuts.
• Material-bonded connections: Liquid threadlockers (e.g. Loctite, Permabond) form a chemical bond in the thread that withstands vibrations while also sealing.

Why do bolt connections fail?

Screw connections can fail for various reasons:

• Dynamic loads: Vibrations or lateral loads loosen the connection.
• Static loads: overload or uneven forces.
• Relative movements: Movements between the connected parts.
• Establishing the connection: material fatigue or yielding under pressure.
• Insufficient clamping length: Too short screws or insufficient thread engagement.

A practical example: An ICE train lost a door while travelling at full speed because a nut in the door locking mechanism came loose, resulting in injuries to passengers. This demonstrates how important reliable screw locks are.

Functionality of anaerobic adhesives

Anaerobic adhesives are a special type of threadlockers that secure and seal screws, bearings, or flanges. They cure only in the absence of air and upon contact with metal. Here's how it works:

• The adhesive is applied to the thread.
• When screwed, it is sealed airtight between the metal surfaces.
• Metals such as iron or copper trigger a chemical reaction that causes the adhesive to harden – often within minutes to hours.

Important: The more metal ions the material provides (e.g. steel, copper), the faster the curing. For passive metals like stainless steel or aluminium, an activator can help.

Advantages of threadlockers

Threadlockers, particularly anaerobic adhesives, offer numerous advantages:

• Single-component: No mixing required.
• Solvent-free: Environmentally friendly and safe.
• Simple handling: Easy to use.
• Disassembly possible: Depending on strength.
• Dosable: Precise application.
• Material connection in the thread: Vibration-proof and durable.
• Corrosion protection: Protects the thread from rust.
• Securing and sealing in one: Saves time and materials.
• Chemical and thermal resistance: Stable from -55 to 150/180 °C.

These benefits help you save time and costs and extend the lifespan of your products.

Tips for Choosing the Right Product

When selecting the appropriate screw locking mechanism, you should consider the following points:

1. Application Requirements

• Solution: Does the fastening need to be removed frequently, occasionally, or never?
• Load: Is the screw subjected to high loads?
• Temperature: What are the minimum and maximum temperatures?
• Chemical influence: Are there effects such as oil or acid?
• Size: What thread size and pitch?
• Material: What material are the screws and components made of?

2. Determine strength

Threadlockers are classified into three strength levels:

Strength	Frequency of removal	Difficulty of removal	Vibrationsschutz
Low	Regularly	Easy	keiner
Medium	Occasionally	Easy	Wenig bis mitel
High	Never	Hard	Viel

With Loctite products, you can identify the strength by the colours: Pink (low), Blue (medium), Red (high). With Permabond, the products are marked with letters such as H (High), M (Medium), L (Low).

3. Check material compatibility

Ensure that the screw locking is compatible with the materials of your fastening:

• Active metals (e.g. iron, steel, copper, brass): Promote hardening.
• Passive metals (e.g. stainless steel, aluminium, galvanised surfaces): Slow down the curing – here an activator or a special product (e.g. Loctite 270 or Permabond HM163) be necessary.

4. Viscosity and Flow Behaviour

• Low-viscosity (thin liquid) products: Ideal for small screws or fine threads, also for subsequent securing.
• High-viscosity (thick) products: Better for larger screws or vertical applications, as they do not run.

The correct viscosity ensures optimal distribution in the thread.

5. Approvals and Standards

For certain applications, certifications such as NSF/WRAS (drinking water), DVGW (gas and water), or KBA (automotive) are required. Our products meet the necessary standards for your safety-critical applications.

Application Tips

The correct application is crucial for the effectiveness of the screw locking. Here are some tips:

• Surface preparation: Ensure that the threads are clean and free from dirt, grease, or contaminants. Use a cleaning agent such as if necessary Permabond Cleaner A.
• Amount for application: Apply a small amount to the threads – usually, a drop is sufficient. Avoid over-application.
• Application location: Apply the adhesive to the male threads before inserting the female thread. For blind holes or cap nuts, apply it directly into the hole or the nut.
• Tightening the fastener: Tighten the screw to the recommended torque specification. Avoid over-tightening.
• Curing time: Allow the adhesive sufficient time to cure before the assembly is subjected to loads. Please refer to the information in the technical data sheet.
• Storage and Handling: Store the products in their original containers at room temperature and keep them tightly closed.
• Safety instructions: Wear gloves and work in a well-ventilated area. Refer to the safety data sheet.

Conclusion

Screw lockings are essential to ensure the safety and longevity of your screw connections. With the right products and correct application, you can ensure that your connections remain reliable even under demanding conditions. If you have any questions or need further information, please do not hesitate to contact us. kontaktierenWe are happy to help you find the best solution for your needs.