Types of Screw Fastening

Common types of screw fastening are as follows:

1. Bolt and Nut
   A bolted joint is used in assemblies where the components have relatively small thickness and where space is not enough to accommodate the bolt head, the nut and the wrench.
   
   There are two methods for increasing the shock absorbing capacity of bolts:
   1. Reduce the shank diameter to core diameter of threads or even less.
   2. Increase the length of shank portion of the bolt.
   The threaded portion of the bolt is the weakest part and maximum elastic energy is absorbed in this region. In a bolt of uniform strength, the entire bolt is stressed to the same limiting value, resulting in maximum energy absorption.
2. Cap Screw
   A screw is mated into a threaded hole in one of the components being assembled, not into the nut. The screw joint is used in assemblies where one of the components is thick enough to accommodate the threaded length of the screw.
3. Studs
   Studs are cylindrical rods threaded at both ends. One end of the stud is screwed into one of the connecting components, while the nut is tightened at the other end. Studs are particularly suitable for positioning the covers of a cylinder head.
4. Machine Screws
   Machine screws are small cap screws with various types of heads, most of which have slots for a screw driver. Machine screws are used in assembly of small machines.
5. Set Screws
   Set screws are used to prevent relative motion between the two parts. The threaded portion of the screw passes through a tapped hole in one of the parts and the point of the screw presses against the other piece, and thus holding two parts together by friction. The points of set screws are hardened to combat early wear.