Side-by-Side Comparison
Head Styles
Countersunk vs. Hex Head
Comparing 2 standards across 13 specifications. 13 key differences identified.
Comparing:
Countersunk
Hex Head
Flat Head (Countersunk / CSK, standardized under ISO 7046 and DIN 965) screws feature a flat top face and a conical tapered underside (90° in ISO Metric, 82° in US Imperial, 100° in Aerospace). Designed to seat inside a matching chamfered hole, the head sits 100% flush with or slightly below the surface of the joined material.
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
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 7046 / DIN 965 / ASME B18.6.3 | ISO 4014 (Partial thread) / ISO 4017 (Full thread) / DIN 931 / ASME B18.2.1 |
|
Head Top Profile
|
100% Flat top face | — |
|
Countersink Angle (ISO Metric / DIN)
|
90 degrees | — |
|
Countersink Angle (US Imperial / ASME)
|
82 degrees | — |
|
Countersink Angle (Aerospace / NAS)
|
100 degrees (for thin structural aircraft skins) | — |
|
Length Measurement Rule
|
Overall Length (Measured from top of head to screw tip) | — |
|
Primary Applications
|
Woodworking, door hinges, machine slides, aircraft aerodynamic skin | — |
|
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) |