Copper rivets are well-known as rustproof, heavy-duty, and permanent fasteners that can hold together countless materials. The first copper reinforcing rivets were invented in 1873 and were crafted specifically to reinforce the pockets on work pants.
Today, copper rivets are used in manufacturing applications because of their strength, resistance to corrosion, and antimicrobial properties, but they’re also ideal for functional items because of their decorative appeal. Copper rivets show up on clothing, saddles, belts, bags, shoes, and more, because they provide a functional and attractive fastening solution.
Here are three special things to consider when using copper rivets in their wide variety of applications:
1. Consciously Clinch Materials
When clinching copper rivets, it’s important to calculate the clinch allowance, which is the amount of material required to roll over in order to secure a tight fit. Also, be sure to note that a compressible material, such as copper, does not provide a firm base for clinching blind rivets. However, you can overcome this either by putting a washer against the copper, with the rivet head on top of the washer, or by using a large-flange rivet with the compressible material under the flange.
2. Calculate Your Job
Copper rivets are often preferred because of their strength, so it’s important to consider the overall weight/torsion that the rivet will support in comparison to the job it needs to perform. In a riveted connection, which joins two plate-like connections or roll-shaped flanges together, the connection is subjected to tension that could pull the connections apart. With this torsional twisting or tearing in mind, you have to determine the forces that act on the connection under normal—and extraordinary—circumstances and what kind of structural failures could occur.
It’s also important to note that rivets become unusable during disassembly, which may or may not make a difference for your application.
3. Avoid Galvanic Corrosion
All metals have a measure of nobility, which is a metal’s resistance to corrosion when it comes into contact with another metal. Galvanic corrosion (also called bimetallic corrosion) is what happens when two dissimilar metals that are fastened to each other come into contact with a common electrolyte, such as water. When this happens, the more noble metal, or cathode, is protected, while the active metal, or anode, is corroded. Copper has one of the highest measures of nobility, so it typically isn’t harmed by contact with other metals but it will cause corrosion in those other materials, especially aluminum and zinc. Additionally, if copper comes into contact with iron and steel and the other metal has a similar mass to or smaller mass than the copper, it can cause galvanic corrosion.
One of the most well-known examples of galvanic corrosion is the Statue of Liberty, whose exterior was made from copper (cathode) and interior was made from cast iron (anode) with only a thin, shellacked asbestos skin. The statue was shut down in 1984 because of structural safety concerns after extensive corrosion was discovered inside the statue, primarily from leaking rain water from the torch in the statue’s right hand. The repairs were extensive and included the removal of the cast iron interior, which was replaced with a low-carbon, corrosion-resistant stainless steel.
When using copper rivets, specifically, make sure to avoid installing them with a metal like aluminium, which could cause a galvanic response. Opt, instead, for metals like stainless steel, brass, and of course, copper. Other preventive options include adding a corrosion inhibitor to the application or applying coatings to both materials. It’s important to note that if you opt to apply a coating, the one on the cathode is the most important and must be of a high quality.