Bolts are mechanical fasteners with a threaded shaft.  They are closely related to screws, which are also mechanical fasteners with threaded shafts.  These types of fasteners are typically inserted through two parts, with aligned holes.

Whether something is a bolt or a screw, depends upon how it is used.  A bolt is inserted through parts that all have threaded holes and a nut is then screwed onto the bolt providing a clamping force and preventing axial movement.  A screw may first pass through a first part with a clearance hole but its threads mate with threads in one of the parts being fastened.  A screw may cut its own threads or mate with a threaded part.

The term bolt is usually used for a fastener that has only part of its shaft threaded.  Fasteners with their entire shaft threaded are normally called screws.

The unthreaded part of the shaft of a bolt is called the shank.  The shaft of the bolt prevents radial movement of the parts, while the head of the bolt and the nut (if fitted), prevents axial movement.  The unthreaded shank provides an interface with the parts that are more precise and less abrasive.  The shank also does not contain stress concentrations that could lead to failure, it is therefore important that the shank extends well beyond the interface between parts if a significant shear force will be placed on the bolt.

A bolt fastens a part to another part with a threaded hole, technically this application is acting as a screw.

Bolts often reply on axial force causing sufficient friction at the threads to remain in place.  A torque is applied to the head to generate this axial force.  The force acts between the bolt head and whatever the bolt is screwed into, whether it be a nut or one of the parts being fastened.  This cause elongation of the bolt and compression of the parts containing clearance holes.  Alternatively, some form of locking nut or thread-locking adhesive may be used to prevent the bolt from loosening.

The most common type of bolt is the hex bolt.  This has a hexagonal shaped head, providing flat surfaces for tools to apply torque when fastening.  An easier manufactured square head was used for older bolts and this is still used today for many applications where very high torque must be applied with a spanner.

We offer the following bolts:-

Rawl Bolts – Zinc

Through Bolts – Zinc

Eyebolts – Bright Zinc Plated

Various sizes are also available.

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