A carriage bolt features a smooth dome head and square neck beneath it. This design prevents rotation during tightening when the neck embeds into materials like wood. Key characteristics include partial/full threading, carbon/stainless steel construction, zinc/galvanized coatings, and standardized sizing (e.g., GB/T 12, DIN 603). Installation requires only one wrench as the square neck locks into a pre-drilled hole. Primarily used in wood/metal assemblies (decks, trailers, furniture) where a smooth finish and anti-tampering are essential.

A threaded fastener converting torque into axial tension, a bolt comprises a head, shank, and threads—coarse for rapid assembly or fine for vibration resistance. Common types (hex head, flange, anchor) address diverse needs. Materials include steel (cost-effective), stainless steel (corrosion-resistant), and titanium (lightweight). Surface treatments like zinc plating or galvanizing enhance durability; strength grades (e.g., ISO 8.8) specify load limits. Heat treatments (quenching, tempering) optimize hardness and toughness. Tightening stretches the bolt, creating preload to resist forces, with thread friction preventing loosening. Installation uses torque wrenches, turn-of-nut, or hydraulic tensioning. By integrating material science, geometry, and precise engineering, this versatile fastener ensures secure, adaptable connections in machinery, construction, and critical systems.

A spring washer is a fastener designed to prevent bolt/nut loosening caused by vibrations, dynamic loads, or thermal shifts. It maintains tension through elastic deformation and friction. Common types include helical (split lock), Belleville (conical), wave, and toothed variants like internal/external serrated washers. Made from carbon steel, stainless steel, or plastics, they feature coatings (zinc, nickel) for corrosion resistance. Their split, wave, or serrated structures store energy when compressed, creating restoring forces. Used in automotive suspensions, aerospace joints, electronics, and machinery, they balance compactness with high load capacity. Proper installation—placing under the nut/bolt head at specified torque—ensures optimal anti-loosening performance without over-compression.

Flat washers and plain washers are often confused due to overlapping terminology. A flat washer is a simple, thin disc with a central hole, designed to evenly distribute fastener loads and protect surfaces. The term plain washer is broader, encompassing basic, non-specialized washers (including flat washers) but may vary regionally. In North America, “flat washer” typically refers to the standard type, while “plain washer” in British contexts may imply the same. Functionally, both prevent surface damage and reduce friction, but plain washers could include variations (e.g., rubber for sealing). Key differences lie in terminology rather than design: flat washers emphasize load distribution, while plain washers may serve general purposes. Always consult industry standards (e.g., ANSI, ISO) for precise definitions, as regional jargon or project specifications dictate usage. In practice, the terms are often interchangeable, but context determines their application.

A flat washer, a thin circular disc with a central hole, serves as a vital component in bolted joints by distributing loads, preventing surface damage, and enhancing joint stability. Its simple design—flat surfaces, precise inner/outer diameters, and variable thickness—ensures compatibility with bolts and workpieces. By spreading compressive forces, it protects soft materials from deformation, reduces vibration-induced loosening, and isolates dissimilar metals to prevent corrosion. Common materials include steel, stainless steel, plastic, and copper, often treated with coatings like zinc or nickel for durability. Applications span construction, automotive systems, electronics, and plumbing. Proper installation involves placing the washer between the fastener and workpiece, followed by torque-controlled tightening. Compact yet versatile, flat washers ensure reliable, long-lasting mechanical connections across industries.