Button Head vs. Hex Head
Comparing 2 standards across 12 specifications. 12 key differences identified.
Button Head Cap Screws (BHCS, standardized under ISO 7380) feature a low-profile rounded dome with a wide load-bearing base and an internal hex or Torx drive recess. Designed for applications requiring a smooth, snag-free finish and low vertical clearance, they provide clean aesthetics on exposed consumer products, 3D printers, and automotive interiors.
Hex Head Bolts (standardized under ISO 4014 / DIN 931 for partially threaded bolts and ISO 4017 / DIN 933 for fully threaded tap bolts) feature a 6-sided external polygon head driven by open-end wrenches, box wrenches, or ratcheting sockets. It is the global benchmark for high-torque heavy structural and automotive clamping.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 7380-1 / ASME B18.3 | ISO 4014 (Partial thread) / ISO 4017 (Full thread) / DIN 931 / ASME B18.2.1 |
|
Flanged Variant
|
ISO 7380-2 (Button head with integrated wide flange collar) | DIN 6921 (Hex head with integrated wide washer flange) |
|
Head Profile
|
Low-profile smooth domed contour | — |
|
Bearing Base Diameter
|
Extra-wide circular bearing base (approx. 1.75 × shank diameter) | — |
|
Drive Recess
|
Internal Hexagon (Allen) or Hexalobular (Torx / ISO 7380-2) | — |
|
Torque Rating
|
Reduced torque rating compared to DIN 912 socket caps (due to shallower socket depth) | — |
|
Primary Applications
|
3D printer motion carriages, motorcycle fairings, electronics rack enclosures | — |
|
Head Geometry
|
— | 6-sided external hexagon with flat top face and circular washer face underside |
|
Common Metric Wrench Sizes
|
— | M6 (10mm), M8 (13mm), M10 (16/17mm), M12 (18/19mm), M16 (24mm) |
|
Common Imperial Wrench Sizes
|
— | 1/4" (7/16"), 3/8" (9/16"), 1/2" (3/4"), 3/4" (1-1/8") |
|
Strength Markings (Metric)
|
— | Class 8.8, 10.9, 12.9 stamped directly on head top |
|
Strength Markings (Imperial)
|
— | Grade 2 (plain), Grade 5 (3 radial lines), Grade 8 (6 radial lines) |