Difference Between Bolt and Screw

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In this article, we will learn about the difference between bolt and screw. Almost in every part that we see around us, whether it is your laptop, mobile, car, motorcycle and a giant machine like an aeroplane, tanks, rockets, etc. all are made by bolts and screws. We all are familiar with the bolts and screws, we have also used them in our daily life but we don’t know the exact difference between them. So let’s learn about the differences.

What is a Bolt?

It is an externally threaded fastener that is designed for the insertion through holes in assembled parts. Generally, bolts have a uniform circular cross-section area.

  • Bolts are always used with nuts and mostly requires spanner and wrenches for loosening and tightening purpose.
  • The parts that are joined with bolts have greater strength and life. This makes bolts a more reliable fastener.
  • The bolts do not have tapered shank but have cylinder shank of uniform cross-section area.
  • The bolts apply compression on the parts on which they are bolted. The bolts are available in different sizes from small to very large sizes.

What is a Screw?

It is an externally threaded fastener that is capable of being inserted into holes in assembled parts. In most of the cases, a screw has pointed tails.

  • Screws are always used without nuts. The threads on screws are helical in structure and have a larger pitch.
  • The screw may or may not have tapered shank and mostly requires screwdrivers or Allen key for tightening and loosening purposes.
  • The parts joined with screw have less strength as compared with bolts.
  • Screws are available in smaller or medium sizes.

Also Read:

Difference Between Bolt and Screw in Tabular Form

S.no.

Bolt

Screw

1. A bolt is an externally threaded fastener designed for insertion through holes in assembled parts and is normally intended to be tightened or released by torquing a nut. A screw is an externally threaded fastener capable of being inserted into holes in assembled parts, of mating with a preformed internal thread or forming its own thread, and of being tightened or released by torquing the head.
2. The bolts have generally uniform cross section.  The screws generally have non uniform cross section.
3. The bolts are always used with the nuts. It is not used with the nuts but used alone.
4. The threads on the bolts are spiral in structure. The threads on the screw are helical in structure.
5. It does not have tapered shank. It has tapered or pointed shank.
6. Bolts mostly require wrenches and spanners for the tightening and loosening
purposes.
The screw requires mostly screwdrivers for tightening and loosening purposes.
7. The parts that are joined together with bolts have greater strength than screw The parts joined together with the screw have less strength than bolt.
8. It is more reliable. It is less reliable.
9. They apply compression on the parts that they join. They don’t apply compression on the parts that they join.
10. The parts that are to be joined with the bolts must have holes for its insertion. Holes may or may not be required in the parts which are to be joined with the screws. In most of the cases, it is directly screwed into the parts to be joined.
11. The bolts are found in smaller as well as in large sizes. The screw sizes are smaller or medium. They are not found in much larger sizes.
12. The examples of bolts are: Anchor bolt, Carriage bolt, Elevator bolt, Flange bolt, Hanger bolt, Hexagon bolt/Tap bolt, Lag bolt, Machine bolt, Plow bolt, Sex bolt, Shoulder bolt, Square head bolt, Stud bolt, Timber bolt, T-head bolt, Toggle bolt, U-bolt, J-bolt, Eye bolts etc. Examples of screws are: Wood screw, machine screw, thread cutting machine screw, sheet metal screw, self drilling sms, socket screw, eye lag, mating screw, set screw etc.

This is all about the difference between bolt and screw. If you found this piece of information useful and valuable then don’t forget to like, share and subscribe to us.


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Pankaj Mishra

Pankaj Mishra is a blogger by passion and Mechanical Engineer by profession. He has completed his B.Tech degree in mechanical engineering in the year 2015. He loves to share his knowledge and help others.

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