Cold riveting no such heat is required, While in hot riveting a suitable heat source for heating rivets. So here this article gives the more key difference between cold riveting and hot riveting to better understand this topic.
Hot riveting:
Hot riveting, the rivet end is heated by some external means before hammering. Heating temperature 2/3 of the melting point of the rivet materials. Due to such heating, the material becomes soft and plastic, and thus the lower upsetting force is required. Hot riveting is preferred basically as lower force is required. It is also favourable for large diameter rivets, and it is usually diameter larger than 10mm. Thermal expansion of rivet due to heating also has an important role in gripping strength.
Cold Riveting:
Cold riveting is performed at room temperature only. The rivet is not too heated and thus hammering is carried out at room temperature. So a comparatively higher force is required for upsetting. However, no heat source is desired for heating as a rivet. Heating time is also not associated with it, so the process is comparatively faster. If the rivet diameter is large or it is made of stronger material a large amount of hammering force is desired.
Difference between hot riveting and cold riveting:
- In hot riveting, the protruding end of rivets is heated to an elevated temperature prior to hammering, while in cold riveting, hammering is carried out at room temperature. No heating is performed.
- Cold riveting no such heat is required, While in hot riveting a suitable heat source for heating rivets.
- In cold riveting no tensile stress develops within rivets, so gripping is not very tight, while in hot riveting volumetric shrinkage, tensile stress develops within rivets as it cools down. This stress helps gripping components tightly.
- Cold riveting may not necessarily leak-proof, while in hot riveting due to tight gripping, hot riveting mostly provides leak-proof joints.
- In cold riveting, no heating time is associated with cold riveting, so it is a faster process. While in hot riveting heating a large number of rivets take time. So hot riveting is a time-consuming process.
- Cold riveting rivets are subjected to shear force only, while in hot riveting rivets are subjected to both shear and tensile force.
- Cold riveting is preferred when the rivet is made of soft materials or its diameter is smaller than 10 mm, while in hot riveting is preferred either when the rivet is made of ferrous metal or when the rivet diameter is more than 10 mm.
- Comparatively higher force is required for upsetting as rivet material remains at room temperature, while in hot riveting lower force is required during upsetting as rivet remains in a plastic state due to heating.
- Hot riveting due to strong gripping force, joints are usually leak-proof, while in cold riveting is not recommended for fluid-tight joining purposes
Similarities between hot riveting and cold riveting:
- Straps plates can be used in both the cases if required.
- Both offer an intermittent joint.
- Both the riveting techniques are required pre-drilled holes on the components for the uses of the passage of rivets. Such holes lead to stress concentration and considerably reduce the load-carrying capacity of the assembled structure due to the reduction of the cross-sectional area.
- Both require hammering or upsetting for making a closing head at the protruding end of the rivet shank, however, the intensity of the hammering force differs.
- Both hot riveting and cold riveting are permanent joining techniques methods. They also fall under mechanical joining techniques.