Metal fabrication is the building of metal structures by cutting, bending, and assembling processes.

Many fabrication shops have specialty processes which they develop or invest in, based on their customers' needs and their expertise:

• Casting
• Powder coating
• Powder metallurgy
• Welding
• Machining

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.

A set of six-axis welding robots

• Interchangeable parts
• Manufacturing engineering
• Contract manufacturing
• Form, fit and function

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. By comparison, machine shops also cut metal, but they are more concerned with the machining of parts on machine tools. Firms that encompass both fab work and machining are also common.
• Blacksmithing has always involved fabrication, although it was not always called by that name.
• The products produced by welders, which are often referred to as weldments, are an example of fabrication.
• Boilermakers originally specialized in boilers, leading to their trade's name, but the term as used today has a broader meaning.
• Similarly, millwrights originally specialized in setting up grain mills and sawmills, but today they may be called upon for a broad range of fabrication work.
• Ironworkers, also known as steel erectors, also engage in fabrication. Often the fabrications for structural work begin as prefabricated segments in a fab shop, they are moved to the site by truck, rail, or barge, and finally, are installed by erectors.