Types of Spring Washers & Locking Washers
1. Split Lock Washers (Helical Spring Washers)
The most common type, featuring a split ring bent into a helical shape. The split creates a spring effect that applies pressure to the fastener. Available in two section profiles:
Square section – Typically used with fasteners having cylindrical heads
Rectangular section (flat section) – Used for all other head types
2. Tooth Lock Washers
Feature serrations or teeth that dig into the fastener and the mating surface to create friction and mechanical interlocking. Subtypes include:
External tooth – Teeth on the outer circumference
Internal tooth – Commonly used in electrical applications where teeth scrape the surface to enhance electrical connectivity
Countersunk – Concave shape with teeth to prevent slippage and absorb shock
3. Wave Spring Washers
Feature a wavy profile providing light to moderate spring forces in tight axial spaces. Designed to absorb shock, maintain consistent pressure on bearings, and eliminate noise and vibration.
4. Belleville Washers (Conical Spring Washers)
Cup-shaped conical washers that provide high spring force in minimal space. Available in Type L and Type H configurations for general-purpose applications.
5. Double Coil Spring Washers
Feature a double-coil rectangular section design as specified in BS 4464. The free height before compression is approximately five times the material thickness.
Technical Specifications
Dimensional Parameters
Key specifications for selecting the correct washer include:
| Parameter | Description |
|---|---|
| Nominal Size (M) | Compatible bolt/screw thread diameter |
| Inside Diameter (d₁) | Clearance hole for the bolt shank |
| Outside Diameter (d₂) | Overall outer dimension |
| Thickness (s / t) | Material thickness |
| Height (h) | Overall height including the helical rise |
Example: M10 spring washer – ID 5.1mm, OD 16mm, Thickness 1.60mm
Material Options
| Material | Characteristics | Applications |
|---|---|---|
| Spring Steel (65Mn, EN42) | High strength, hardened | General industrial fastening |
| Stainless Steel A2 (304) | Good corrosion resistance | Indoor, general purpose |
| Stainless Steel A4 (316) | Excellent corrosion resistance, marine-grade | Marine, chemical, outdoor |
| Phosphor Bronze | Corrosion resistant, non-sparking | Electrical, marine |
| Silicon Bronze | High corrosion resistance | Harsh environments |
| Acetal / Nylon | Non-conductive, lightweight | Electrical insulation, lightweight assemblies |
Hardness Specifications
| Standard | Hardness Range |
|---|---|
| DIN 127 Spring Washers | 430–530 HV |
| Split Lock Washers (Steel) | 42–50 HRC (412–513 HV) |
| Conical Spring Washers (DIN 6796) | 420–490 HV |
| Stainless Steel Split Washers | ≥34 HRC (≥336 HV) |
Surface Finishes
Plain / Oiled
Zinc Plated (clear, yellow, blue)
Phosphated / Black Oxide
Nickel Plated
Chrome Plated
Hot-Dip Galvanized
Industry Standards
Spring and locking washers are manufactured to meet rigorous international standards:
| Standard | Description |
|---|---|
| DIN 127 | Split lock washers – Type A (tang ends) & Type B (flat ends) |
| DIN 7980 | Spring lock washers with square ends |
| DIN 6796 | Conical spring washers for fastening joints |
| ASME B18.21.1 | Helical spring-lock washers (regular, heavy, extra-duty & high-collar) |
| BS 4464 | Metric series spring washers, helical construction, M1.6 to M68 |
| BS 2061 | Phosphor bronze spring washers – single & double coil |
| ISO 7089 | Plain washers – general requirements |
| JIS B 1251 | Japanese Industrial Standard for spring washers |
| GB/T | Chinese national standards for locking washers |
Applications
Spring washers and locking washers are specified in applications where fastener security is critical:
Industrial Machinery – Pumps, compressors, motors, gearboxes
Automotive – Engine components, suspension systems, chassis assemblies
Aerospace – Airframe structures, engine mounts, control systems
Oil & Gas – Valves, pipelines, offshore platforms
Electrical Equipment – Switchgear, control panels, busbar connections
Construction – Structural steel connections, heavy equipment
Railway – Rolling stock, track infrastructure
Renewable Energy – Wind turbines, solar installations
Selection Guide: Spring Washer vs. Lock Washer
Choose Spring Washers When:
Continuous vibration and dynamic motion are present
Maintaining preload is critical across varying operating conditions
Thermal expansion/contraction cycles are expected
The application requires compensation for bolt relaxation
Choose Lock Washers When:
Components experience shear forces or lateral movements
Standard vibration protection is sufficient
Mechanical interlocking is preferred over spring preload
Combined Use
In demanding applications, both types can be used together—a spring washer maintains tension while a lock washer provides additional resistance against loosening.
Quality & Testing
Quality spring washers undergo rigorous testing to ensure performance and reliability:
Material composition analysis – Verification of alloy content
Hardness testing – HV or HRC verification
Coiling and twist testing – Ensuring proper helical formation
Compression testing – Verifying spring characteristics under load
Decarburization inspection – Ensuring surface integrity
Free height measurement – Verifying dimensional accuracy
