Machining is the family of processes that give a part its shape by removing material, most often as chips, with a cutting tool. You start from a blank (bar, plate, block, forging or casting) and work towards the geometry on the drawing, dimension by dimension.
The main processes are milling, turning, drilling and grinding, plus electrical discharge machining (EDM), which removes material with sparks. Modern machines are driven by a CNC control that runs a program produced by CAM software. A complete job is generally done in two stages: roughing, which removes a lot of material quickly, then finishing, which is slower and delivers the dimensions, tolerance and surface finish.
Machining suits precision parts in small and medium runs, prototypes, one-off spare parts and shapes that casting or forging cannot produce accurately enough: cylinder bodies, flanges, shafts, sensor brackets, tooling, special-machine components. It works metals and engineering plastics alike, with excellent repeatability. Its main drawback is material waste: the larger the blank compared with the finished part, the higher the cost. The guide to the price of CNC machining explains what a quote includes, and the CNC machining page presents the usual services.
In a quote request. Attach the dimensioned drawing and the 3D model, then state the material and grade, the quantity per order and per year, the tolerances and roughness values that are genuinely critical, and the treatments or inspections you expect (material certificate, dimensional report). Anything that is not functional can stay within general tolerances, which cuts cost without harming the part.