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DIN 603:2017 Large Round Head Square Neck Bolt

DIN 603:2017 Large Round Head Square Neck Bolt has a large round bearing head and a square neck that prevents rotation. It is suitable for exposed joints where a smooth appearance and self-locating installation are desired.

Typical applications include wood structures, fences, shelving, vehicle accessories, agricultural machinery, and light steel-wood assemblies. The large round head provides better coverage, while the square neck seats into the prepared hole to resist turning.

During installation, the square neck should be matched with a square hole or suitable base material for reliable seating. For outdoor and wood-structure uses, corrosion protection, head appearance, and matching thread hardware strongly affect service life.

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Dimensions unit: mm

Thread size d M5 M6 M8 M10 M12 M16 M20
P Pitch 0.8 1 1.25 1.5 1.75 2 2.5
b L≤125 16 18 22 26 30 38 46
125<L≤200 22 24 28 32 36 44 52
L>200 / / 41 45 49 57 65
dk Max. 13.55 16.55 20.65 24.65 30.65 38.8 46.8
Min. 12.45 15.45 19.35 23.35 29.35 37.2 45.2
ds Max. 5 6 8 10 12 16 20
Min. 4.52 5.52 7.42 9.42 11.3 15.3 19.16
k1 Max. 4.1 4.6 5.6 6.6 8.75 12.9 15.9
Min. 2.9 3.4 4.4 5.4 7.25 11.1 14.1
k Max. 3.3 3.88 4.88 5.38 6.95 8.95 11.05
Min. 2.7 3.12 4.12 4.62 6.05 8.05 9.95
r1 10.7 12.6 16 19.2 24.1 29.3 33.9
r2 Max. 0.5 0.5 0.5 0.5 1 1 1
r3 Max. 0.75 0.9 1.2 1.5 1.8 2.4 3
s Max. 5.48 6.48 8.58 10.58 12.7 16.7 20.84
Min. 4.52 5.52 7.42 9.42 11.3 15.3 19.16
 Thousand pieces of steel weigh ≈kg  - - - - - - -
Thread length b  - - - - - - -

① Material:

a) Steel, strength grade: 4.6, 4.8, 8.8 according to DIN EN ISO 898-1

b) Stainless steel, strength grade: A2-70, A4-70 according to DIN EN ISO 3506-1

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Hangzhou Better Fastener
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Better Fastener is a professional fastener enterprise specializing in the manufacturing of steel washers, stainless steel washers, spring washers and sealingwashers. Founded in 2001 as a washer factory, the company expanded into a comprehensive enterprise integrating washers, nuts, bolts, spring nuts and other fastener products in 2010.

The company positions itself as a provider of comprehensive one-stop services for customers, relying on technological R&D, industrial investment and trade distribution.

With an experienced professional team and a sound sales network, Better Fastener has achieved excellent sales performance in both domestic and foreign markets,and has grown into one of the competitive manufacturers and suppliers in China's industrial fastener industry.

Better Fastener is committed to becoming a trusted fastener supplier for customers with reliable product quality, reasonable prices and on-time delivery

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