Although often overlooked, the nut is essential for ensuring a firm and durable connection. Its function is to complement the bolt, maintain constant tightness and resist the tensile loads or vibrations to which a fastener is subjected.
Main types of nuts used in industry and construction
These are the most common types of nuts, their standards, technical characteristics, and typical uses.
Hexagonal nuts: the most universal model. Their shape allows for tightening with a spanner or socket and good torque transmission. Manufactured in steel or A2/A4 stainless steel and in strength classes 8 or 10. Applications: metal structures, machinery and industrial installations.
Self-locking nuts: incorporate a nylon ring or metal deformation that prevents loosening due to vibration. They replace spring washers or chemical fasteners. Applications: automotive, agricultural machinery and equipment subject to constant vibration.
Structural nuts: designed for prestressed joints in steel structures, they offer greater height and a more robust design than a standard hexagonal nut, improving stress distribution and performance under high loads. They are used in metal structures, industrial buildings, bridges and supports where mechanical strength and long-term reliability are essential.
Lock nuts: all-metal, with controlled deformation locking. Temperature and wear resistant. Applications: engines, exhaust systems and high-heat machinery.
Blind nuts: they close the end of the screw, protecting the thread from moisture, dust, or impacts. They also provide a clean and aesthetic finish.
Wing nuts: designed to be tightened and loosened manually, without tools. They allow for quick assembly and frequent adjustments.
Square nuts: offer a wider support surface and reduce the risk of rotation in specific housings. Applications: metalwork, light structures or assemblies with U-profiles.
Long nut or union nut (DIN 6334)
Union nuts: connect two threaded rods while maintaining alignment. Applications: suspension systems, conduits, and support structures.
Weldable nuts: designed for spot or arc welding, creating permanent joints. Applications: chassis, frames and fixed metal structures.
Slotted nuts: incorporate a pin that prevents loosening, even with torsion. Applications: shafts, steering systems and heavy machinery.
Flanged nuts: serrated or smooth base that distributes the load and eliminates the need for washers. Applications: automotive, lightweight structures and quick fastenings.
Rivetable or insertable nut
Rivetable nuts: create a strong thread in sheet metal or thin materials. They are installed with a riveting tool. Applications: car bodies, metalwork, panels and enclosures.
Most commonly used materials and finishes
Nuts are manufactured in different materials and coatings depending on the environment of use:
- Zinc-plated steel: basic protection against corrosion indoors.
- A2 stainless steel: high resistance to moisture and oxidation, ideal for outdoor use.
- A4 stainless steel: better protection against marine or chemical environments.
- Brass or technical polymers: electrical, light or decorative applications.
How to choose the right nut
Choosing the right nut ensures safety and durability. Consider these key aspects:
Compatibility with the bolt
The thread (metric, fine, UNC or UNF) and strength class (e.g. 8.8 or 10.9) must match. An inferior nut may deform sooner and compromise the joint.
Conditions of use
- In environments with vibration, use self-locking nuts or metal safety nuts.
- For high temperatures, avoid nylon and choose metal versions.
- In humid or corrosive environments, opt for A2 or A4 stainless steel.
Type of assembly
- In permanent joints, weldable nuts offer maximum safety.
- If frequent adjustments are required, choose wing nuts or flanged nuts.
- In visible assemblies, cap nuts improve protection and aesthetics.
Load distribution
In soft materials or those with little support surface, square nuts or flanged nuts distribute the load better and prevent deformation.
Regulatory compliance
Choose DIN or ISO nuts, which ensure compatibility and consistent quality.
The right nut makes all the difference
Choosing the right nut is no minor detail: the safety and reliability of any joint depends on it.
At CHAVESBAO, you will find a complete range of DIN and ISO nuts in different materials, finishes and locking systems, designed to meet the demands of industry, construction and mechanical engineering.
