Below is a list of Screw Machining manufacturers from Ontario, California. Screw machining is a precision manufacturing process that fabricates screws and other threaded parts by the selective removal of material. The end product of screw machining is a screw. Screws can be made from a variety of materials such as hardened metals, steel alloys or plastics. They are produced from screw machines, which are powered mechanical devices. Other machine tools include drill presses, gear shapers, lathes, milling machines and planers.