Helical split lock washer, flat washer, or internal tooth washer

Because washers are pre-assembled, they eliminate the need for manual assembly on the production line, significantly reducing labor costs and the risk of dropped or missing parts.

The standard defines the specifications for cross-recessed head screws with captive washers , commonly known in the industry as "Sems" screws. These specialized fasteners feature pre-assembled washers that are mounted onto the screw blank before the threads are rolled, ensuring the washers remain permanently attached and free-spinning. Core Specifications of JIS B 1188

Usually includes just a split lock washer or a flat washer.

You can obtain the official, full-text technical documentation through several authorized standards distributors: JIS B1188 Double Washer Sems

JIS B 1188 is often categorized into specific types based on the washer assembly:

These fasteners are staple components in the electronics, automotive, and appliance industries due to their reliability in high-vibration environments. Accessing the JIS B 1188 PDF

The standard specifies that the pan head's diameter and height are slightly smaller than a standard DIN or ISO pan head, making them ideal for compact electronics. Technical Benefits & Applications