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Defines the types of slotted screws covered (M1.4 to M10, with some extended ranges for pan head). It explicitly excludes self-tapping screws (JIS B 1122) and hexagon bolts.
The screws covered by JIS B 1188 are often referred to as —a term derived from "screw and washer assembly." The standard defines a manufacturing process where the washer is mounted onto the screw blank before the threads are rolled, making the washer permanently captive.
In standard manufacturing processes, putting a washer onto a screw manually during assembly is time-consuming and prone to human error (such as forgetting the washer entirely). JIS B 1188 outlines the parameters for screws where the washer is placed onto the screw blank before the threads are rolled. Once the threads are rolled, the outer diameter of the thread becomes larger than the inner hole of the washer, permanently trapping the washer on the screw. The Anatomy of a SEMS Screw (JIS B 1188) jis b 1188 pdf
Often case-hardened and coated with trivalent zinc, nickel, or black oxide for general-purpose applications.
Understanding JIS B 1188: Cross-Recessed Head Screws with Captive Washers
For full, official technical tables, dimensional drawings, and material specifications, you should refer to the official standard documentation. This public link is valid for 7 days
The standard specifies requirements for cross-recessed head screws with captive washers (commonly known as SEMS screws).
What (e.g., M3, M4, M5) are you designing around?
JIS B 1188 applies to screws made from two primary material groups: Can’t copy the link right now
JIS B 1188 fasteners are primarily used for general purposes in mechanical engineering and electronics. They feature a cross-recessed (typically Phillips) pan head combined with one or more free-spinning but captive washers.
Used inside Electronic Control Units (ECUs), dashboard assemblies, and sensor brackets where vibrations are constant and regular washers could vibrate loose.
Assembling household machinery where vibration resistance is needed.
It is worth noting that on , the Japanese Industrial Standards (Japanese Industrial Standards) were officially renamed to Japanese Industrial Standards (Nihon Sangyō Kikaku) . However, the technical content of the standards remains unchanged.