You are here: Difference Between Hot Riveting and Cold Riveting: Why Pull Rivet Nuts Belong to Cold Riveting - BISUDI
In riveting processes, hot riveting and cold riveting are two completely different technical routes. Many customers ask when choosing automatic rivet nut guns or automatic riveting machines: should our product use hot or cold riveting? Which category do pull rivet nuts belong to? This article explains the differences at three levels - principle, equipment and application scenarios - and why sheet metal, chassis/cabinets and new energy industries generally adopt cold riveting.
I. Core differences between hot and cold riveting
| Comparison Item | Hot Riveting | Cold Riveting |
|---|---|---|
| Forming principle | Heat the rivet to red-hot, upset-form while plasticity is raised | At room temperature, cold-deform the fastener by pulling or pressing force |
| Heating required | Heating equipment needed (furnace, induction, electric riveting gun) | No heating, driven pneumatically/electrically/hydraulically |
| Typical fasteners | Solid rivets, semi-tubular rivets (large diameter, high-strength steel) | Blind rivets, pull rivet nuts, press-in fasteners |
| Workpiece impact | Has heat-affected zone, may deform, discolor or damage coating | No thermal deformation, can be assembled after painting |
| Operation mode | Mostly double-side operation with a bucking bar, high ambient temperature | Single-side construction, handheld or automated |
| Typical scenarios | Bridges, vehicle chassis, heavy steel structures, large aviation parts | Chassis/cabinets, sheet metal, home appliances, automotive parts, new energy |
II. Pull rivet nuts belong to cold riveting
Pull rivet nuts are pulled axially by the gun head screw at room temperature, causing the nut shank to cold-extrude and bulge on the backside of the plate, which is a typical cold deformation (cold riveting) process; blind rivets that break the mandrel to form are likewise cold riveting. Cold riveting produces no high temperature and will not cause plate warping, annealing or coating discoloration, so it is especially suitable for appearance parts that have already undergone painting, powder coating or anodizing, and also for materials that conduct heat quickly and deform easily when heated, such as aluminum and thin steel plate.
III. Why thin plates and automated lines mostly choose cold riveting
First,controllable deformation: thin plates warp very easily when heated, while cold riveting has stable forming force and a flat plate surface; second,single-side construction: the backside of chassis, square tubes and closed cavities is unreachable, and hot riveting needs a bucking bar so it cannot work, while cold riveting completes the job with one gun; third,easy automation: cold riveting has a stable cycle, no heating wait and no open flame or fumes, making it easy to build auto-feed equipment or robot cells, suitable for batch lines; fourth,safer and more environmentally friendly: there are no high temperature, welding fumes or fireproofing requirements, yielding a better workshop environment and lower labor intensity.
IV. Common question: is cold riveting strong enough
For thin-plate connections, reliability is usually determined not by "hot or cold" but by fastener selection and forming quality. Structural blind rivets and hexagonal and knurled pull rivet nuts are widely used on automotive and new energy structural parts, and their pull-out force and torque can be looked up by specification and verified through coupon pull-out tests. Only true large-diameter, high-strength steel load-bearing joints (such as heavy frames and bridges) must use hot riveting. It is recommended to tell the manufacturer the workpiece load requirements and select based on pull-out test data, rather than deciding on the impression that "hot is stronger". For pull rivet nut types seeWhat Types of Pull Rivet Nuts: Type Comparison。
Hot/Cold Riveting FAQ
Process Selection FAQ
No, and there is no need to. Automatic rivet nut guns are cold riveting equipment designed for the cold deformation of pull rivet nuts; hot riveting requires a hot riveting tong or machine with heating function.
Yes, this is one of the advantages of cold riveting - assembly after painting does not damage the coating; just control hole positions and gun-seating angle per the process.
The deformation of pull rivet nuts is small and concentrated on the nut itself, with limited impact on the plate; conventional aluminum veneers and profiles show no abnormality in long-term use, and key load-bearing parts can undergo pull-out verification.
The two fasteners have different gun heads and forming principles, so automatic riveting machines and automatic rivet nut guns are generally configured separately; robot workstations can achieve multiple processes by changing guns.
Unsure which riveting process to use? Send samples for evaluation
Customers can book on-site visits to do cold riveting sampling and pull-out tests with real workpieces, consultation hotline +86 13556668682.
V. Can products already using hot riveting switch to cold riveting
Many traditional sheet metal and vehicle parts were designed for hot riveting years ago; switching to cold riveting requires three things: first, redesign the connection, replacing solid rivets with blind rivets or pull rivet nuts (positions needing subsequent screw assembly should prioritize pull rivet nuts); second, verify strength by doing pull-out, shear and vibration tests per the original joint load requirements, confirming the substitution is feasible with data; third, evaluate the line - cold riveting needs no heating station or fume extraction, and the workshop layout is actually simpler. Products that are already thin plate, single-side reachable and assembled after painting usually gain in both deformation control and automation from switching to cold riveting; while large-diameter high-strength steel load-bearing joints should retain hot riveting. In mixed production, keep the two fastener types, hole types and tools managed separately to avoid misassembly.
Cold riveting saves the heating furnace, fume extraction and heat-resistant tooling, and handheld equipment has a modest unit price; auto-feed and robot cells require higher investment, but calculated against saved labor and energy, batch lines usually have a short payback period; it is recommended to trial-calculate per workpiece.
Further reading:Uses, Working Principle and Common Problems of Automatic Rivet Nut Guns · Blind Rivet Knowledge Summary · Automatic Rivet Nut Gun
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