Sheet Metal Fabrication is the building of metal structures by cutting, bending, and assembling processes. It is a value added process that involves the creation of machines, parts, and structures from various raw materials. A fabrication shop will bid on a job, usually based on the engineering drawings, and if awarded the contract will build the product. Large fab shops employ a multitude of value added processes in one plant or facility including welding, cutting, forming and machining. These large fab shops offer additional value to their customers by limiting the need for purchasing personnel to locate multiple vendors for different services. Metal fabrication jobs usually start with shop drawings including precise measurements, then move to the fabrication stage and finally to the installation of the final project. Typical projects include loose parts, structural frames for buildings and heavy equipment, and stairs and hand railings for buildings.
Sheet Metal Fabrication generally consists of three key processes – cutting, bending and assembling. Let’s look at each of these in more detail.
Cutting – this is the process of taking the raw material in the form of sheet steel and cutting it into the basic shape that will then be folded to create a three-dimensional structure in the next stage. There are a number of different ways to cut sheet metal, however the best results are obtained by CNC hydrolic punches, which are both fast and accurate.
Bending – Once the shape has been cut out of the sheet metal, it can be folded to create the intended form. This is not unlike constructing a cardboard box from a flattened pack – although it requires specialist machines and expert knowledge to accomplish successfully! Bending may be done automatically or manually and various machines may be used, most commonly the press-brake. Just like with cutting, CNC plays an important role in modern methods.
Assembling – Assembling refers to the process of joining the pieces together and may use a single technique or a variety of techniques depending on various requirements such as stress levels, water tightness, etc. Common assembling techniques include welding, crimping (where the metal is held together by further bending) riveting and threaded fasteners.