Cap nuts are used similarly to hexagonal nuts but feature a design that prevents the main nut from sliding easily. They require specialized tools for tightening, including live spanners, dull spanners, dual-purpose spanners (open part), or special square-hole socket spanners.

These nuts are primarily used for:

• Rough and simple mechanical parts
• Automotive applications (tires, front/rear axles of cars, tricycles, electric vehicles)
• Road light frame bases
• Equipment exposed to sunlight and rain

Primarily used with bolts and screws for fastener connections. Classified by nominal thickness into Type I, Type II, and thin varieties. Type I nuts (for grades above 8) are further divided into A, B, and C levels:

• A/B level: For machines/structures requiring smooth surfaces and high precision
• C level: For rougher surfaces and lower precision requirements
• Type II: Thicker design, ideal for frequent assembly/disassembly

Also known as welded nuts, these are melted at high temperatures and welded between products for secure fastening. Benefits include:

• Exceptional fastening security
• Resistance to loosening
• Wide applications in construction, transportation, and building materials