Find HS Code and trade information for spring washer

Spring Washer

A spring washer, also known as a split lock washer, is a type of washer used to maintain tension between bolted joints, preventing loosening due to vibration and other dynamic loads. It achieves this through its split design, which provides a spring force.

Material

Spring washers are commonly manufactured from:

• Spring Steel: The most frequent material due to its high elasticity and ability to return to its original shape after deformation. Often coated for corrosion resistance.
• Stainless Steel: Used in corrosive environments or applications requiring hygiene, offering good corrosion resistance.
• High-Strength Carbon Steel: Employed in heavy-duty applications where greater load-bearing capacity is needed, typically with a protective coating.

Purpose

The primary purpose of a spring washer is to:

• Prevent Loosening: Maintain clamping force in bolted connections, especially under vibration, shock, and thermal cycling.
• Compensate for Thermal Expansion/Contraction: Accommodate slight changes in bolt length due to temperature fluctuations.
• Distribute Load: Spread the load over a wider area, reducing stress on the joined materials.
• Provide a Slight Locking Action: The split design creates friction and resists movement.

Function

The function of a spring washer relies on its split geometry. When a bolt is tightened, the washer deforms, creating a spring force. This force:

• Increases Friction: The split edges dig into the mating surfaces, increasing friction between the washer, bolt, and joined materials.
• Maintains Tension: Even if the bolt attempts to loosen, the spring force continues to exert pressure, resisting movement.
• Provides Resilience: The washer can absorb minor vibrations and shocks without losing clamping force.

Usage Scenarios

Spring washers are commonly used in:

• Automotive: Engine components, chassis, exhaust systems.
• Construction: Structural connections, machinery mounting.
• Machinery: Equipment assembly, vibration-prone applications.
• Electronics: Securing components in devices.
• Plumbing: Fixture installation, pipe connections.

Common Types

• Split Lock Washers: The most common type, featuring a split on one side. Available in various thicknesses and diameters.
• Wave Washers: Feature a wavy profile, providing a spring force in both directions. Used in applications requiring controlled deflection.
• Curved Washers: Offer a lower spring force than split or wave washers, suitable for lighter applications.
• Belleville Washers (Conical Spring Washers): Conically shaped washers that provide a high spring force in a small space. Often used in stacks to achieve desired load characteristics.
• Tooth Lock Washers: Feature teeth on the outer edge to bite into the mating surface, providing a more aggressive locking action.

Spring washers are categorized under screws, bolts, nuts, coach screws, screw hooks, rivets, cotters, cotter pins, washers (including spring washers) and similar articles, of iron or steel. Two specific HS codes apply, depending on whether they are threaded or non-threaded.

• 7318210030: This HS code covers screws, bolts, nuts, coach screws, screw hooks, rivets, cotters, cotter pins, washers (including spring washers) and similar articles, of iron or steel; Non-threaded articles; Spring washers and other lock washers Helical spring lock washers. Chapter 73 relates to articles of iron or steel. Heading 7318 specifically covers screws, bolts, nuts, etc. Subheading 7318210030 further defines non-threaded articles within this category, specifically helical spring lock washers. The basic customs tariff is 5.8%, with an additional tariff of 25.0%, and a further 30.0% after April 2, 2025. Steel and aluminum products are subject to the 25% additional tariff. The total tariff rate is 85.8%.

• 7318210090: This HS code also covers screws, bolts, nuts, coach screws, screw hooks, rivets, cotters, cotter pins, washers (including spring washers) and similar articles, of iron or steel; Non-threaded articles; Spring washers and other lock washers Other. Similar to 7318210030, Chapter 73 relates to articles of iron or steel, Heading 7318 covers screws, bolts, nuts, etc., and Subheading 7318210090 defines other non-threaded articles within this category. The basic customs tariff is 5.8%, with an additional tariff of 25.0%, and a further 30.0% after April 2, 2025. Steel and aluminum products are subject to the 25% additional tariff. The total tariff rate is 85.8%.

Regarding HS codes 7318210030 and 7318210090, please note the need to verify steel or aluminum content, as these materials are subject to an additional 25% tariff.