There are many benefits to using permanent assembly processes to assemble a product. Once manufacturers decide that they need a permanent assembly process, they must design their part in such a way to meet their functional requirements and align with the chosen assembly process. Two of the most crucial design factors when using solid rivets are the diameter and length of the rivets or tenons being formed. Through 40+ years of experience, Orbitform’s Assembly Experts have created design guidelines for solid rivets that provide a good starting point for product design engineers.
Rivet Diameter Design Guidelines
The diameter of the rivet or tenon is largely dependent on the hole diameter that the rivet will be placed in. Typically, the rivet diameter should be about .010” - .015” (.254 mm - .381 mm) smaller than the hole diameter. To save cost, it may be wise to select the rivet diameter first to ensure it is a standard size and not a custom rivet that may have a higher cost. Then, engineers can design the hole diameter to be .010” - .015” (.254 mm - .381 mm) larger than the rivet.
Rivet Length Design Guidelines
The rivet length depends on the part stack up of the components being assembled as well as the process being used and the rivet diameter.
When using the Orbital Forming process for solid rivets, less material is usually required than would be for impact or squeeze riveting. This is due to the forming force being applied at an angle and the minimal shank swell introduced into the rivet or tenon. It is suggested that the length of the stick out that protrudes through the part stack up prior to forming should be about 50-60% of the rivet diameter. For example, if you are using an 1/8” (3.175mm) rivet, the stick out should be about .062” (1.575 mm) – meaning the length of your rivet should be equal to the part stack up plus .062”. This is only a rule-of-thumb as this percentage can change based on the desired finished form specifications.
For Impact Riveting solid rivets, the rule-of-thumb is that the rivet stick out that protrudes through the part stack up prior to riveting should be about 100% of the rivet diameter. For example, if you are using an 1/8” (3.175mm) rivet, the stick out should be about .1/8” (1.575 mm) – meaning the length of your rivet should be equal to the part stack up plus 1/8”.
Rivet Design Confirmation via Orbitform’s Solutions Lab
While these general guidelines can help product design engineers get started when designing their products for assembly, there are still many factors that can affect the rivet diameter and length needed for an application. This can include material, finished form specifications, functional requirements, and more. The best way to confirm if the right rivet has been selected is to partner with Orbitform’s Solutions Lab discuss the design and produce prototypes. In our lab, we can assemble sample parts with your rivet as designed and make suggestions for design improvements.
With 40+ years of manufacturing and assembly experience, our Assembly Experts have supported tens of thousands of assembly applications. Contact us today for assistance in designing your product for assembly.