Square Nut

Square Nut — Four-Sided Nut | DIN 557 / DIN 562 | Large Bearing Surface Design

Square nuts feature a four-sided design that provides a larger bearing surface than standard hex nuts, offering better resistance to loosening and improved load distribution. Manufactured to DIN 557 (heavy/flat) and DIN 562 (thin) standards, our square nuts are available in M3 to M24 sizes in carbon steel and stainless steel. The flat sides prevent rotation when embedded in wood or metal channels, making square nuts the preferred choice for furniture manufacturing, trailer beds, railway connections, and applications where the nut must sit flush against a flat surface.

Material & Specifications

Size Range	M3 to M24 / 1/8″ to 1″
Standard	DIN 557 (heavy square), DIN 562 (thin square), ANSI B18.2.2
Material	Carbon Steel (Grade 4, 5, 8), 304 Stainless Steel (A2), 316 Stainless Steel (A4)
Surface / Coating	Hot-Dip Galvanized, Electroplated Zinc (Blue/White, Yellow/Color), Dacromet, Multi-Element Alloy Co-Permeation, Plain/Black Oxide
Type	DIN 557 (full height) or DIN 562 (thin/low profile)
Thread Type	Metric Coarse (M), UNC

Surface Treatment & Zinc Coating Quality

Square nuts are frequently used in outdoor and industrial environments where corrosion resistance is essential. We provide five premium coating options:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (50-120μm) providing superior corrosion protection for outdoor structural and trailer applications. Compliant with ISO 1461 / ASTM A153. Salt spray resistance: 500-1,000+ hours.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright silver-blue finish with 5-15μm zinc layer. Cr3+ passivation, RoHS compliant. Suitable for furniture and indoor applications requiring clean appearance.
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Multi-colored passivation providing 100-200 hours salt spray resistance with a golden-iridescent finish. Preferred for machinery and equipment where visual identification of coating is needed.
• Dacromet Coating — Advanced water-based zinc-chromium coating with no hydrogen embrittlement risk. 1,000+ hours salt spray resistance. Ideal for railway, mining, and heavy industrial square nut applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-rare earth alloy layer offering 2,000+ hours salt spray resistance. Self-healing at scratches. Used in critical infrastructure, power grids, and coastal installations.

Key Features

• Larger bearing surface than hex nuts — better load distribution and anti-loosening
• Flat sides prevent rotation in channels, slots, and embedded applications
• Full surface contact when used against flat materials (wood, sheet metal)
• Available in both full-height (DIN 557) and thin (DIN 562) profiles
• Easy to tighten with pliers or wrench in confined spaces

Applications

• Furniture manufacturing and cabinetry assembly
• Trailer beds and railway connections
• Wooden structures and timber framing
• Sheet metal ducting and enclosure assembly
• Bed frames, gates, and fencing hardware

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust
• 15+ Years of Export Experience — serving 40+ countries worldwide
• Full Traceability — material certificates (EN 10204 3.1) and test reports included
• Custom Packaging & OEM/ODM — your brand, your specifications
• Third-Party SGS / Bureau Veritas Inspection Available
• 24-Hour Quote Response — same-day reply for urgent requirements