Hex Head vs. Truss Head
Comparing 2 standards across 12 specifications. 12 key differences identified.
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.
Truss Head screws (also known as Mushroom Head / Extra-Wide Pan) feature an extra-wide, low-profile domed head with a large-diameter flat bearing underside. Designed to span large clearance holes and clamp thin sheet metal without tearing or requiring external flat washers, they are widely used in metal building framing and cabinet door hardware.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 4014 (Partial thread) / ISO 4017 (Full thread) / DIN 931 / ASME B18.2.1 | ASME B18.6.3 / IFI Standards |
|
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) | — |
|
Flanged Variant
|
DIN 6921 (Hex head with integrated wide washer flange) | — |
|
Head Diameter Ratio
|
— | Extra-wide base (D_k ≈ 2.2× to 2.5× shank diameter) |
|
Head Height Profile
|
— | Ultra-low curved dome (flatter and wider than standard pan head) |
|
Bearing Surface
|
— | 100% Flat horizontal bearing surface with maximum surface contact area |
|
Common Drive Recesses
|
— | Phillips (PH2), Square (Robertson #2), Combo, Slotted |
|
Primary Applications
|
— | Thin sheet metal ducting, electrical junction boxes, cabinet drawer slide tracks |