Tube and pipe bending is big businesses, and a huge variety of customers from plumbers to car mechanics require the services of a professional pipe bending workshop for their business needs. However, this constant demand for pipe bending services has caused the industry and the methods it uses to diversify enormously, and there is now a wide variety of methods used to create strong, safe pipe bends. Choosing which one is right for your pipe bending needs can be difficult.
One of the most popular methods of pipe bending is rotary draw bending, a reliable method where the pipe in question is slowly bent around a round, slowly-rotating bending die. This method provides more than adequate results for a number of purposes, but if you really want to achieve top-quality bends in your piping you should seriously consider asking for mandrel-assisted bending.
What is a mandrel?
In basic terms, a mandrel is a specially shaped object with a diameter that allows it to fit snugly into the pipe being bent. Some mandrels consist of simple steel rods or balls which are shaped for ease of insertion, while others consist of linked ball-bearings or even bags full or sand or ice.
Whatever a mandrel is made from, they all serve basically the same purpose. When used alongside rotary draw bending machines, the internal support they provide when inserted properly grants the pipe considerable structural strength during the stressful bending process. The additional support provided by a mandrel creates a bend of considerably higher quality than a bend achieved without mandrel assistance, and using mandrels can also grant other advantages.
What are the advantages of choosing mandrel bending over regular rotary draw bending?
- Minimal loss of diameter -- The solid support provided by a mandrel prevents a pipe from kinking and collapsing while it is being bent, keeping the overall diameter of your chosen pipe as close to its original width as possible. When conducted carefully and with properly specialised mandrels, a pipe can retain the exact same diameter even when bent to very sharp angles.
- Minimal loss of wall thickness -- The kinks and distortion that can be caused by bends created without a mandrel can also cause your pipe walls to become very thin in and around the bent sections of the pipe. As you can imagine, this reduces the pipe's strength significantly around the bent area, and is a particular problem for pipes expected to carry high internal water or gas pressures. With the aid of a mandrel, this loss of wall thickness is minimised, keeping your pipe's strength almost constant along its entire length.
- Best option for fragile pipes: Mandrels are considered essential equipment when it comes to bending certain fragile types of piping, such as the slender and relatively malleable copper piping used in many residential plumbing systems. These pipes almost invariably become kinked or distorted when bent with beinding presses or other methods, and even regular rotary draw bending can cause unforeseen damage to these delicate pipes. With the support of a mandrel, these pipes can be bent much more effectively, and are allowed to retain virtually all of their limited structural strength.
