Screw locks are essential for ensuring the reliability and safety of your screw connections. Whether in technical devices, furniture, vehicles, or industrial equipment, they ensure that your connections remain tight and secure even under vibration, dynamic loads, or other influences. In this article, you will learn how to select and use the right screw locks to provide optimal protection for your applications.
What are screw locks?
Screw locks are specialized products that prevent screw connections from loosening unintentionally. They increase the safety and durability of connections that are exposed to vibrations or other stresses. There are different types:
- Settlement protection: Compensates for the settling behavior of the material and maintains the preload force (e.g., tension washers, disc springs).
- Anti-rotation device: Prevents mechanical loosening by means of additional components such as lock nuts.
- Chemical bonding: Liquid threadlockers (e.g., Loctite, Permabond) form a chemical bond in the thread that withstands vibration and seals at the same time.
Why do screw connections fail?
Screw connections can fail for various reasons:
- Dynamic loads: Vibrations or transverse loads loosen the connection.
- Static loads: Overloading or uneven forces.
- Relative movements: Movements between the connected parts.
- Setting the connection: Material fatigue or yielding under pressure.
- Insufficient clamping length: Screws too short or insufficient thread engagement.
A real-life example: An ICE train lost a door at full speed because a lock nut in the door lock came loose, resulting in injuries to passengers. This shows how important reliable screw locks are.
How anaerobic adhesives work
Anaerobic adhesives are a special type of threadlocker that secures and seals 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 together, it is enclosed 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 process. An activator can help with passive metals such as stainless steel or aluminum.
Advantages of screw locks
Threadlockers, especially anaerobic adhesives, offer numerous advantages:
- Single-component: No mixing required.
- Solvent-free: Environmentally friendly and safe.
- Easy handling: Easy to use.
- Disassembly possible: Depending on strength.
- Dispensable: Precise application.
- Material closure in the thread: vibration-proof and durable.
- Corrosion protection: Protects the thread from rust.
- Fastener and seal in one: saves time and material.
- Chemical and heat resistance: Stable from -55 to 150/180 °C.
These advantages help you save time and money and extend the service life of your products.
Tips for choosing the right product
When selecting the appropriate screw lock, you should consider the following points:
1. Application requirements
- Loosening: Does the fastening need to be removed frequently, occasionally, or never?
- Load: Is the screw exposed to high loads?
- Temperature: What are the minimum and maximum temperatures?
- Chemical exposure: Are there any influences such as oil or acid?
- Size: What thread size and pitch?
- Material: What material are the screws and components made of?
2. Determine strength
Screw locks are classified into three strength levels:
strength | frequency of removal | difficulty in removal | vibration protection |
Low | Regularly | Simple | nobody |
means | Occasionally | Simple | Little to moderate |
High | Never | Heavy | A lot |
With Loctite products, you can tell the strength by the colors: pink (low), blue (medium), red (high). With Permabond, the products are labeled with letters such as H (high), M (medium), L (low).
3. Check material compatibility
Ensure that the screw lock is compatible with the materials of your fastening:
- Active metals (e.g., iron, steel, copper, brass): Promote hardening.
- Passive metals (e.g., stainless steel, aluminum, galvanized surfaces): Slow down curing—an activator or special product (e.g., Loctite 270 or Permabond HM163) may be necessary.
4. Viscosity and flow behavior
- Low-viscosity (thin) 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 optimum distribution in the thread.
5. Approvals and standards
Certifications such as NSF/WRAS (drinking water), DVGW (gas and water), or KBA (automotive) are required for certain applications. Our products meet the necessary standards for your safety-critical applications.
Tips for use
Correct application is crucial for the effectiveness of the threadlocker. Here are a few tips:
- Surface preparation: Ensure that the threads are clean and free of dirt, grease, or contaminants. If necessary, use a cleaning agent such as Permabond Cleaner A.
- Amount to use: Apply a small amount to the threads—usually one drop is sufficient. Avoid overuse.
- 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 nut.
- Tightening the fastener: Tighten the screw to the recommended torque specification. Avoid overtightening.
- Curing time: Allow sufficient time for the adhesive to cure before subjecting the assembly to stress. 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. Observe the safety data sheet.
Conclusion
Threadlockers are essential for ensuring the safety and longevity of your screw connections. With the right products and correct application, you can ensure that your connections remain secure even under demanding conditions. If you have any questions or require further information, please do not hesitate to contact us. We will be happy to help you find the best solution for your needs.
