This rigorous review process ensures that JIS B 1188 remains aligned with global best practices and evolving industrial requirements. In 2021, the standard was reaffirmed, confirming its continued validity.
The standard also defines the material, usually carbon steel or stainless steel, and acceptable plating, such as zinc plating or passivation. Applications of JIS B 1188 Screws
: Often cited as a more cost-effective choice compared to patented conical washer alternatives. Cons :
The standard specifies the characteristics of cross-recessed head screws, typically featuring a pan head, which are pre-assembled with captive washers. "Captive" means that the washers are held in place under the head of the screw, preventing them from falling off during shipping or installation, yet allowing them to spin freely. jis b 1188 pdf
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Usually a Pan Head (Cross-recessed/Phillips drive).
The standard categorizes assemblies based on the type of captive washers used. The most common configurations found in the PDF tables include: This rigorous review process ensures that JIS B
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 dictates the mechanical, dimensional, and material requirements for cross-recessed head screws with captive washers , commonly known in the manufacturing industry as SEMS screws. A complete understanding of this standard is vital for engineers, assembly technicians, and procurement managers in the electronics and automotive fields, where ensuring the correct fastener geometry prevents catastrophic assembly failures. Official, authorized digital copies of the code can be purchased through authorized distributors such as the Accuris Standards Store or the ANSI Webstore . What is a JIS B 1188 Fastener?
: You can view the dimensions for small pan Phillips screws with double washers in the RC Fastener Spec Sheet Dimensions & Materials ITP Bolt Catalog Applications of JIS B 1188 Screws : Often
The standard covers both steel and brass screws intended for general-purpose applications. The most common configuration is a machine screw combined with one or two captive washers. Standard Specifications Material Carbon steel (Class 4.8), Stainless steel (A2), and Brass Head Type Pan Head (Small pan head is 5%–20% smaller than standard) Washer Types
A common configuration, often highlighted in ITP Bolt’s summary , is the double washer sems screw, which features two washers under the head:
Fastener manufacturers (e.g., Sunco, Yamashina, or global suppliers like Misumi) offer free, downloadable and CAD models that mirror the exact dimensions layout of JIS B 1188.
The Jis B 1188 standard plays a crucial role in ensuring the quality and reliability of socket set screws used in various industries, including:
Either a single washer (flat or lock) or double washer configuration. Captive Design: The washer is held captive on the shank. JIS B 1188 Double Washer Sems Configuration