screws and bolts

What is the Difference between Bolt and Screw : Bolt vs Screw

Bolts and screws are mechanical fasteners used to position and hold two or more components together. Most peoples assume both bolt and screw are same fastener type. But it’s not true. Most bolts can works as screws if used in threaded components. There is no defined difference between bolt and screw. But they have unique purpose and characteristics. In this article we will discuss the  difference between bolt and screw. Read this article to know the types of screw.

What is Bolt

Bolt is a type of externally threaded fastener, used to position and hold two or more components together. Bolts do not hold in the material, They are generally used along with washers and nuts for high duty applications. During installation, torque in applied to nut to position and hold components together. Examples: Hex Bolt, Anchor Bolt, Eye Bolt etc.

What is Screw

Screw is a type of externally threaded fastener, used to position and hold two or more components at one place. Screws are installed in a pre-drilled tapped hole or they create threads during installation. They do not require nuts and used for relatively low clamping force requirements. During installation, torque is applied to screw itself. Examples: Wooden Screw, Self tapping plastic screws, machine screw etc. Read this article for more details on screws.

Bolt vs Screw

CharacteristicsBoltsScrew
ApplicationNuts are required to secure a bolt.Screws works on its own.
Torque is applied to nut.Torque is applied to screw
Bolts are used with un-threaded components.Screw can be used with threaded or un-threaded components.
ConstructionUniform cross section.Can have non-uniform cross section.
Uniform ShankNon Uniform Shank
Clamping ForceBolts along with nuts provide high clamping force.Used for low clamping force requirements.
ReliabilityHighModerate
Load Carrying CapacityLarger size bolts are used to achieve higher load carrying capacity. For example bolts are used in construction industry.Screws are not available in very large size. They are generally used for low load carrying applications.
ExamplesAnchor bolt, Carriage bolt, Elevator bolt, Flange bolt, Hanger bolt, Hexagon bolt/Tap bolt, Lag bolt, Machine bolt etc.Self tapping screws, wooden screws, sheet metal
screws, Machine screws, Security head screw, unidirection screws etc.

Summary

To sum up, It is very difficult to differentiate between bolt and screw. Most bolts can be used as screws if used with threaded components. You can check out type of washers and their application here.

Got Questions?  We will be happy to help.

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