Washer vs. lock washer: the surprising difference that could save you money

When it comes to assembly and fastening, the sequence of components plays a crucial role in ensuring the stability and integrity of the final product. One common question that arises in this context is whether washers should be placed before or after lock washers. This blog post delves into the nuances of this topic, providing a comprehensive guide to the proper sequence for secure fastening.

Understanding Washers and Lock Washers

Washers are thin, disc-shaped components designed to distribute the load of a fastener over a larger surface area, preventing damage to the mating surface and reducing the risk of loosening.

Lock washers, on the other hand, are specialized washers that prevent fasteners from loosening due to vibration or other external forces. They achieve this by creating a spring-like effect against the fastener and the mating surface.

The Sequence: Washer Then Lock Washer

The general rule of thumb is to place the washer first, followed by the lock washer, and then the fastener. This sequence ensures that:

• Load distribution: The washer distributes the load of the fastener evenly, protecting the mating surface.
• Lock washer effectiveness: The lock washer is positioned against the washer, allowing it to effectively engage with both the fastener and the mating surface, preventing loosening.
• Proper tightening: The sequence allows for proper tightening of the fastener, ensuring a secure connection.

Exceptions to the Rule

While the washer-then-lock-washer sequence is generally recommended, there are certain exceptions to this rule:

• Countersunk fasteners: When using countersunk fasteners, the lock washer is placed first, followed by the washer. This is because countersunk fasteners have a tapered head that fits into a recessed hole, and the lock washer prevents the fastener from sinking too far into the hole.
• Self-locking fasteners: Self-locking fasteners, such as Nylok nuts, incorporate a nylon insert that prevents loosening. In this case, a washer may not be necessary.

Benefits of Using Both Washers and Lock Washers

Using both washers and lock washers offers several benefits:

• Increased load bearing capacity: Washers increase the surface area of the fastener, allowing it to bear higher loads.
• Reduced risk of loosening: Lock washers prevent fasteners from loosening due to vibration or external forces.
• Protection against wear and tear: Washers protect the mating surface from damage caused by the fastener.
• Improved sealing: Washers can help create a better seal between the fastener and the mating surface.

Other Considerations

In addition to the sequence, there are other factors to consider when using washers and lock washers:

• Washer size: The washer should be large enough to cover the entire bearing surface of the fastener.
• Lock washer type: Different types of lock washers have different strengths and applications. Choose the appropriate type based on the specific requirements.
• Tightening torque: Follow the manufacturer’s recommendations for tightening torque to ensure proper fastening.

Wrapping Up: A Secure Fastening Strategy

Understanding the proper sequence for washers and lock washers is essential for ensuring secure fastening. By adhering to the general rule of washer then lock washer, or considering the exceptions and other factors discussed in this post, you can achieve reliable and durable connections in your assembly projects.

Frequently Asked Questions (FAQs)

Q: Why is it important to use both washers and lock washers?
A: Using both washers and lock washers provides increased load bearing capacity, reduces the risk of loosening, protects against wear and tear, and improves sealing.

Q: How do I choose the right type of lock washer?
A: Consider the specific application, load requirements, and vibration levels to select the appropriate type of lock washer. Common types include split lock washers, star washers, and wave washers.

Q: What is the difference between a flat washer and a lock washer?
A: Flat washers distribute the load of the fastener, while lock washers prevent loosening due to vibration or external forces. Lock washers have a spring-like design that creates friction against the fastener and mating surface.

Q: Can I use a washer without a lock washer?
A: In some cases, using a washer without a lock washer may be sufficient, especially for static applications with minimal vibration. However, for critical applications or where vibration is a concern, using both washers and lock washers is recommended.

Q: How tight should I tighten a fastener with a washer and lock washer?
A: Follow the manufacturer’s recommended tightening torque for the specific fastener and lock washer combination. Overtightening can damage the components or strip the threads.