Understanding screw and bolt

Screw and bolt are very similar but also have some major dissimilarities, but they are types of fasteners typically made of metal. They are characterized by a helical ridge, called male thread (external thread). Screw and bolts are used in fastening materials of different types such as metal, plastic, rubber, ceramic, etc. They are used by engaging the screw thread with a similar female thread (internal thread) of a matching part.

Today you’ll get to know the definition, applications, types, working, advantages, and disadvantages of screw and bolt over other joining processes. You’ll also get to know the difference between screws and bolts.

What are screw and bolt?

Screws are a broad category of mechanical fasteners with a threaded shaft, designed to screw into a part.  They are often self-threading (also called self-tapping) where the thread goes into the material when the screw is turned. It creates an internal thread that pulls the fastened material together and prevents pull-out.

Different types of screws are available for a variety of materials including wood, sheet metal, and plastic, which are commonly fastened by screws. The wood screws and self-topping screws have a tapered shaft with sharp threads designed to cut a mating thread in the part to which they are fastened. There is also a machine screw, which is more like a bolt but has its entire shaft threaded. On the other hand, Bolts.

Bolt and screw can be accurately known by their applications. A bolt can pass through an unthreaded holes in parts and is secured by a nut. Unlike a screw that mates with a threaded hole in one of the parts being fastened. Although this definition of a bolt is not strictly applied. The term bolt is used for a fastener that is not self-tapping and has only part of its shaft threaded. They are normally known as screws if the fasteners are either self-tapping or have their entire shaft threaded.

Screws rely on friction at the threads to remain securely fastened. In a self-tapping screw, radial expansion of the hole causes much of this friction. In the case of machine screws, the friction is mostly caused by axial force resulting from the torque applied to the head and the subsequent tension in the screw combined with compression of the parts. Although, machine screws may alternatively, or can additionally use a locking nut or thread-locking adhesive to prevent loosening.

Read more: Understanding the various types of fasteners

Applications of screw and bolt

Applications of screw and bolt are common today since it offers a greater benefit over other joining processes. In fact, almost all industrial applications can be design to use the fastener only that some factors must be considered. Things to considered include:

• Threading
• Applied load on the fastener
• Stiffness of the fastener
• Also, the number of fasteners required must be taken into account.

When choosing a fastener for a given application, some things must also be put into consideration. These include:

• Accessibility
• Installation process
• Environment occurrence such as temperature, potentially corrosive elements, and water exposure.
• Weight restrictions
• Materials to be joined

Common applications of screws and bolts around us include chairs, tables, studs, doors, windows, kitchen utensils, electrical devices, etc. Broad use of fasteners are automotive industries, aviation, agricultural equipment, marines, etc. in fact, anywhere equipment is dealt with fasteners are always put into consideration.

Types of screw and bolt

Below are the various types of screws and bolts.

• Countersunk heads
  • 1. Decking screws
  • 2. Pan-head screws
  • 3. Hex cap screws
  • 4. Carriage bolts
  • 5. Lag bolts
  • 6. Hammer drive screws
  • 7. Square head bolts
  • 8. Socket-head cap screws
  • 9. Oval head screws
• Non-countersunk heads
  • 10. Wood screws
  • 11. Sheet metal screws
  • 12. Thread-rolling screws
  • 13. Socket-head screws
  • 14. Set screws
  • 15. Weld screws
  • 16. Raised or slotted cheese screws
  • 17. Fillister head screws
  • 18. Drywall screws

Read more: Understanding rivets and riveted joints

• Combination heads
  • 19. Concrete or masonry screws
  • 20. Machine screws
  • 21. Modified truss screws
  • 22. Washer-faced screws
  • 23. Thread-cutting machine screws
  • 24. Self-drilling SMS
  • 25. Self-tapping screws
  • 26. Framing screws
• Tamper-resistant heads
  • 27. Tamper-resistant screws
• Screw-type bolts
  • 28. Sex bolts
  • 29. Eyebolts
  • 30. J-bolts
  • 31. U-bolts
  • 32. Shoulder bolts
  • 33. Elevator bolts
  • 34. Hanger bolts

Read more: Tire definition, applications, components, types, & material

Difference between screw and bolt

Universally, there is no accepted distinction between a screw and a bolt, however, there is a simple distinction that is often true, although not always. This fact is that a bolt passes through a substrate and takes a nut on the other side. On the other hand, the screw takes no nut since it threads directly into the substrate. In short term, a screw screws into something, a bolt can bolt several things together. So, nuts are not required when using screws for applications, but bolts are often sold with matching nuts. The difference between bolt and screw is likely due to regional or dialectical differences.

Furthermore, the machinery’s handbook describes screw and bolt distinctly. A bolt is an externally threaded fastener designed or inserted through holes in assembled parts. Normally, it is designed and intended to be tightened and released by torquing a nut. A screw is an externally threaded fastener designed to be inserted into holes in assembled parts of mating with a preformed.

Read more: Understanding chain drive

Watch the video below to learn more about screw and bolt:

Advantages and disadvantages of screw and bolt

Advantages:

Below are the benefits of screw and bolt in their various applications:

• Weight reduction in the component is typically achieved.
• Ability to join high-strength steel up to a tensile strength of Rm = 1500 MPa.
• Minimum space requirements are needed within the tool.
• Tool maintenance is easy and simple.
• Capable of joining a wide range of sheet metal thickness with only one nut type t = 0.5 to 5mm.
• All surface-coated sheet metal panels are feasible.
• Easy and simple installation in every work direction.

Read more: Understanding the working of shock absorber

Disadvantages:

Despite the good advantages of screw and bolt, some limitations still occur. Below are the disadvantages of these fasteners in their various applications:

• Extra weight is added to the components.
• Bond lines are obvious.
• They require holes that weaken the components.
• They carry all the load at specific points, which contributes to fatigue.
• Difficulty of refastening
• Corrosion, and
• Force precision.

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• Most common types of Spanners and their uses

Conclusion

Screws are a broad category of mechanical fasteners with a threaded shaft, designed to screw into a part.  They are often self-threading (also called self-tapping) where the thread goes into the material when the screw is turned. a bolt passes through a substrate and takes a nut on the other side. Whereas, the screw takes no nut since it threads directly into the substrate. But there is no universally accepted distinction between a screw and a bolt. That is all for this article, where the definition, applications, types, working, advantages, and disadvantages snd difference between screw and bolt have been discussed.

I hope you get a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!