Bolt

Fine-thread bolts have a greater number of threads per inch than coarse-thread bolts, which allows for a tighter grip and better holding strength under high-vibration conditions. Fine threads are typically used in precision applications where additional holding power and alignment are crucial, while coarse-thread bolts are easier to install and are often chosen for structural or heavy-duty applications where quick assembly and resistance to stripping are needed.

The head shape of a bolt affects how it is fastened and the type of tool needed for installation. Hex bolts, for example, have a six-sided head, allowing for easy gripping with a wrench and are ideal for high-torque applications. Carriage bolts have a rounded head and a square neck, which prevents them from rotating during installation, making them suitable for wood applications. Each head shape is designed to meet the needs of specific tasks, balancing ease of use with strength and stability.

Bolts are often coated to enhance their durability and resistance to corrosion, especially when exposed to harsh environments. Common types of coatings include zinc plating, which provides a basic level of rust protection, and galvanization, which offers stronger, long-lasting corrosion resistance for outdoor applications. Other coatings like black oxide or phosphate can also improve wear resistance and provide a smoother finish, depending on the intended use of the bolt.