Mechanical joining has been in manufacturing for a long time as a way to join tubing to flanges and fittings without the need to weld. Actually, a mechanical joint is stronger than a welded joint. A mechanical joint can withstand over 20,000 pounds of hydrostatic pressure. Here are five things you should know about mechanical joining tools.
They are easy to use: Mechanical joining tools require limited training to operate and any training required can be learned in minutes. All resources needed to learn and operate these tools are easily available online. Mechanical joining tools are used on manual electric rolling motors, pneumatic motors, special machines and in rare cases, on CNC machines.
Mechanical joints are stronger than a welded joint: When a joint is mechanically joined, it becomes more secure than ever. A mechanical joint will not leak, pull apart, or come loose due to pressure, vibrations or temperature change. Because a mechanical joint will not leak, vibrate loose, or pull off when properly installed, engineers who design hydraulic or pneumatic systems consider it superior to welded or brazed joints.
Mechanical joining works with almost all materials: Virtually every tubing material besides plastic can be mechanically joined. The one caveat is the tube must either be annealed or is ductile. Annealed and ductile materials include but are not limited to, steel, stainless steel, aluminum, titanium, copper, cupronickel, and inconel.
Can welded tubing be mechanically joined? Yes, it can, if the end of the tubing has been annealed. If it is not annealed the tube will split. DOM (drawn over mandrel) tubing is the preferred type of tubing but with the annealing process welded tubing can be mechanically joined.
Is it best to roll tubing to a diameter size or to a torque setting? It depends. Rolling to a torque ensures consistent results regardless of tolerance and variations of the tube OD, wall thickness and component ID (flange, fitting, etc.). The torque can be controlled with a torque wrench or with an Elliott torque controller. Rolling to a diameter will guarantee a consistent ID of the tube. This makes it possible to dwell at the set diameter, “iron out” and round up the ID of the tube.