What is the Difference Between Bolt and Screw?

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The main difference between bolts and screws lies in their shapes and how they are used to fasten objects or materials together. Here are the key differences:

  1. Shapes: Screws have a tapered shaft and are often self-tapping, meaning they can create their own thread in a material as they turn. Bolts, on the other hand, have a non-tapered shaft and require a nut to stay secure.
  2. Installation: Bolts are typically installed through holes in assembled objects and are tightened by torquing the nut, which is secured with a wrench. Screws are installed by turning their heads, either in a preformed hole or by creating their own thread in the material.
  3. Threads: Bolts are used to assemble unthreaded objects, while screws are used to assemble objects with threads.
  4. Applications: Bolts are typically used for securing objects with unthreaded holes, while screws are used for objects with threaded holes or those that require the screw to create its own thread.
  5. Costs: Screws are often shorter and can be tapered, which makes them more cost-effective than bolts.

In summary, bolts are fastened with a nut and are used to secure unthreaded objects, while screws are installed by turning their heads and are used to secure threaded objects or create their own thread in the material.

Comparative Table: Bolt vs Screw

The main difference between bolts and screws lies in their purpose, installation, and the objects they are used to fasten. Here is a table comparing the key differences between bolts and screws:

Characteristic Bolts Screws
Purpose Bolts are primarily used to fasten two unthreaded objects together, often requiring a nut for fastening. Screws are designed to fasten or secure components by threading directly into the material.
Head Shape Bolts typically have a flat, washer-like head. Screws often have a variety of head shapes such as flat, round, pan, hex, etc..
Nut Requirement Bolts require a separate nut to secure the joint. Screws do not require a nut; they thread directly into the material.
Thread Direction Bolts can have threads running partially or entirely along the shank. Screws have threads running the length of the shaft.
Application Bolts are generally considered stronger and more durable than screws, making them suitable for heavy-duty applications like construction and manufacturing. Screws are often preferred for applications where aesthetics are important, as their heads are usually smaller than those of bolts and can be hidden more easily.

In summary, bolts are typically used with unthreaded objects and nuts, while screws join objects with pre-cut threads. Bolts are generally stronger and more durable than screws, making them ideal for heavy-duty applications, while screws are often preferred for their aesthetic appeal and ease of installation.