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JIS Code
fasteners
JIS B 1180 Hexagon Head Bolt Specifications Reference Guide
Japanese Industrial Standard defining dimensional sizes and flats clearances for hexagon head machine bolts.
Standard Scope
Specifies the dimensions, thread parameters, and property class options for hexagon head steel bolts in metric sizes. It acts as the standard mechanical reference for bolt head sizes and clearances in machinery designed in Japan.
Typical Applications
- •Industrial assembly clearances sizing.
- •Fastener clearances audit for Japanese machinery.
- •Metric bolting layout and spacing.
Key Engineering Concepts
Width Across Flats (s)
The head width parameter dictating wrench or socket clearances during assembly.
Wrench Clearance
The envelope space required around the bolt head to apply tightening tools.
Strength Classifications
Metric classes (like 8.8 and 10.9) specifying fastener yield and tensile strength limits.
Engineering Notes & Best Practices
- •JIS head flats can differ slightly from ISO 4014 standards for specific sizes (e.g. M10 is 14 mm flat in JIS vs 16 mm in ISO; M12 is 17 mm flat in JIS vs 18 mm in ISO).
- •Always verify tool clearances when substituting between JIS and ISO metric fasteners.
- •Proper thread engagement length must match the nut material strength.
Official Standards Reference
JIS B 1180Official Store
Hexagon head bolts
Japanese Industrial Standard detailing hexagon bolts shapes, threads, and sizes.
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