Why use special riveting technology
When looking for a riveting welding factory to cooperate with, many bosses often only focus on the quotation . As a result, once the workpiece is under load, it will crack and deform, resulting in the need for repairs, and the cost of these repairs is even more than double the money saved in order to save costs.
Why is the strength of special riveting higher than that of welding?
Special riveting is a process that mainly relies on applying continuous pressure to the plate to allow the two pieces of material to engage in a cold state. The result is that there is no heat-affected zone around the connection. For those riveted joints on aviation aluminum alloy frames, their tensile strength is 15 to 20 percent higher than that of welds of the same specifications.
The whole process does not need to be in a state of high-temperature melting, so the metal grains inside it will not be disrupted. This will ensure that the original strength data of the material itself does not need to be discounted. Therefore, the design margin can be made smaller, and the weight of the structure will be reduced accordingly.
Why can’t complex structures be welded but riveted?
Shells with internal cavities and multiple thin plates stacked together as well as components with special shapes are deformed due to the increase in temperature during welding, which will cause the dimensions to deviate and leave some bubbles in the innermost part of the weld.
The special riveting technology is to fix them tightly in a row-by-row order under ordinary room temperature environment, so that the deformation degree of the entire structure can be controlled within a smaller range of one millimeter, specifically within the range of 0.2 millimeters.
The fuel tank of the spacecraft and the car body floor of the high-speed rail all use this type of structure. After the riveting process is completed, the assembly accuracy can reach the micron level. Because such high precision is achieved, there is no need for finishing in the subsequent stages, and the overall cost is lower.
How intuitive is the fatigue life gap?
When a welded joint is subjected to alternating loads, the stress concentration coefficient Kt at the weld toe usually exceeds 2.5, so cracks may develop after 100,000 cycles. In contrast, the connection surface distribution of riveted joints is continuous, so the stress concentration coefficient Kt will be reduced to about 1.3, which directly increases the service life three to four times.
In 2023, the ship's factory changed the original welding method to riveting. The data from fatigue tests on that rib joint on the hull changed. The previous data was 120,000 times, but later it became 450,000 times. The maintenance interval has also changed. It used to be two years, but later it was extended to seven years because of the use of special riveting technology. The service time of the entire ship has also become longer, specifically by several years.
Process plan is the real threshold for manufacturers
Manufacturers that can provide specific solutions for special riveting will clearly write down the entire process and details from how to select the plate, what is the tolerance range of pre-punched holes, how to select the specific specifications of rivets, what is the detailed curve of applied pressure, and what is the final testing standard. Those small factories usually can only blindly copy off-the-shelf engineering drawings. Once conflicts and contradictions are found between nodes at different locations during on-site construction or processing, This will lead to stagnation and the inability to deliver the product on time.
As of 2024, the total number of riveting companies that can pass NADCAP aviation system certification in our country has not reached 400. As for the companies that can independently come up with a complete technology package, the number is only about 80 at most. Putting this situation here, anyone with a discerning eye can see that this is indeed the kind of resource that is truly scarce.
What are the hard questions to ask when choosing a factory?
First, you need to ask what the material of the rivet is and whether it has a batch traceability record. Then ask whether the constant pressure method or the constant displacement method is used when applying pressure. Finally, at the end, you must get a non-destructive testing report. The gap between those who can give specific parameter tables on the spot and those who can only say that they have rich experience can be seen at once with the eyes.
In 2025, a certain main engine manufacturer conducted a bidding process. At that time, three companies participated in the bidding. As a result, only one of the companies provided a complete FMEA failure analysis report. In the end, the company successfully won the bid. Its one-time delivery inspection pass rate of workpieces reaches 99.2%. However, the other two companies were all stuck in the process verification process and failed.
How much will you lose if you choose the wrong factory?
On the face of it, it saved 20,000 to 30,000 yuan in processing costs. However, after the workpiece had been running on the line for three months, two stress fractures occurred. The total cost of downtime and recall reached more than 400,000 yuan. Riveting itself is a form of concealed engineering. After the rivet is driven inside, it cannot be seen from the outside surface at all. By the time the problem actually occurs, it is already too late.
Find those riveting and welding factories that have the conditions for people to sit down and check the process parameters one by one in order. Spend an extra two days in the early stage for communication and coordination. In the later stage, the risk cost of the entire production line is saved. This economic account is worthwhile no matter how you calculate it.
Have you ever had a workpiece on hand and the manufacturer only gave you a quotation but no process plan? Please tell us about your experience in the comment area. If you find it useful, please give it a thumbs up and forward it to your fellow manufacturers.
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