Traditionally, a bolt is a partially or non-threaded cylindrical fastener that is used with a nut to join materials. A screw, on the other hand, is always fully threaded and can be fastened directly into a material without requiring a nut.

The size depends on the application and the materials being joined. It is important to consider both the diameter and length to ensure a secure and durable connection. A general rule is that the screw length should be at least twice the thickness of the top material being fastened.

Screws and bolts are commonly made from materials such as steel, stainless steel, and brass. The choice of material affects corrosion resistance and strength. For example, stainless steel is ideal for outdoor and humid environments due to its rust resistance.

These numbers indicate the strength rating of the screw or bolt. The first number represents tensile strength in hundreds of megapascals (MPa), while the second number, multiplied by 10, shows the yield strength ratio. For example, 8.8 means a tensile strength of 800 MPa and a yield strength of 640 MPa (80% of 800 MPa).

Thread pitch is the distance between thread peaks on a screw or bolt. It affects how quickly a screw tightens or loosens and how strong the connection is. A finer thread pitch provides a stronger connection but requires more turns to tighten or loosen.

A nut and bolt or screw must have the same thread size and pitch to fit together. Always check the markings on both the nut and the bolt/screw to ensure compatibility.

Electro-galvanization applies a thin zinc coating through an electrolytic process, providing basic corrosion protection. Hot-dip galvanization, on the other hand, dips the screw in molten zinc, creating a thicker, more durable coating that is better suited for outdoor and harsh environments.

No, screws are designed for specific materials. Wood screws have deep threads to grip wood fibers, while machine screws have finer threads designed for metal applications. Using the wrong type may result in weak connections and potential damage.

An Allen screw (hex socket screw) has a hexagonal hole in the head and is tightened using an Allen wrench (hex key). It is commonly used in applications where the screw head needs to be flush with or below the surface or where space is limited.

To prevent a nut from loosening, you can use: Lock nuts (e.g., nylon-insert lock nuts). Spring washers to increase friction. Thread-locking compounds to create a secure hold

These methods help keep the nut in place, even under vibrations or heavy loads.