Spring Washer (Split Lock Washer)

Spring Washer is a ring-shaped component installed between a bolt and a nut. It uses the elastic force of the spring to prevent loosening of the thread.

It is also commonly referred to as a spring lock washer and is often abbreviated as SW.

Main types of spring washers:

• Standard type
• Heavy-duty type (thicker material, higher spring force)
• Type for socket/cap screws
• Reverse-wound type (used for left-hand threads)

Applicable standards:

• JIS B 1251 (Type 2: standard type, Type 3: heavy-duty type)
• Cap type & reverse type (domestic Japanese standards)
• DIN 127B
• ANSI B18.21.1 (standard & heavy-duty types)
• GB 859 (standard type)
• GB 7244 (heavy-duty type)