Process of implementation
Metal fabrication is the creation of metal structures by cutting, bending and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials.
Typically, a fabrication shop bids on a job, usually based on engineering drawings, and if awarded the contract, builds the product. Large fab shops employ a multitude of value-added processes, including welding, cutting, forming and machining.
As with other manufacturing processes, both human labor and automation are commonly used. A fabricated product may be called a fabrication, and shops specializing in this type of work are called fab shops. The end products of other common types of metalworking, such as machining, metal stamping, forging, and casting, may be similar in shape and function, but those processes are not classified as fabrication.
- Cutting is done by sawing, shearing, or chiselling (all with manual and powered variants); torching with handheld torches (such as oxy-fuel torches or plasma torches); and via numerical control (CNC) cutters (using a laser, mill bits, torch, or water jet).
- Bending is done by hammering (manual or powered) or via press brakes, tube benders and similar tools. Modern metal fabricators use press brakes to coin or air-bend metal sheet into form. CNC-controlled backgauges use hard stops to position cut parts to place bend lines in specific positions.
- Assembling (joining of pieces) is done by welding, binding with adhesives, riveting, threaded fasteners, or further bending in the form of crimped seams. Structural steel and sheet metal are the usual materials for fabrication; welding wire, flux and/or fasteners are used to join the cut pieces.
Fabrication comprises or overlaps with various metalworking specialties:
- Fabrication shops and machine shops have overlapping capabilities, but fabrication shops generally concentrate on metal preparation and assembly (as described above). Machine shops cut metal, but focus primarily on the machining of parts on machine tools. Some firms do both fab work and machining.
- Blacksmithing has always involved fabrication, although that term has not always been used.
- Welder-produced products, often referred to as weldments, are examples of fabrication.
- Boilermakers originally specialized in fabricating boilers, but the term is now used more broadly.
- Millwrights originally specialized in setting up grain mills and saw mills, but now perform a wide range of fabrication.
- Ironworkers, also known as steel erectors, also engage in fabrication. They often work with prefabricated segments, produced in fab shops, that are delivered to the site.