Screw machine parts are turned parts created in high volumes. Basically, a screw machine, whose cutting methods are like a highly automated lathe, turns/faces the rod of material and advances the rod for the next part. Bar stock is gripped by a spring collet of the spindle, which rotates the stock. The automatic movement, depth and duration of all cuts are controlled by cams. The turret automatically positions each tool. Lever-operated cross slides carry the tools at right angles to the spindle. The main drive shaft of a screw machine provides power to the machine bed's lead work shaft and controls the two front cam shafts. The machine motor, located at the base of the machine, is the central power source for all operations and will vary in horsepower, depending on the size of the machine, speed and stock to be machined. Screw machines are equipped with a mechanical safety clutch that will disengage to stop the main drive shaft, in the event of overloading or jamming, in order to protect the operating mechanisms.

Automatic screw machines can be single- or multi-spindled. Multi-spindle screw machines can machine from four to twelve bars at a time. The stacked type is like four machines in one, as it can produce four complete pieces during one machining cycle. The spindles of an indexing type of a multi-spindle screw machine progressively cut the bar stock, making no identical cuts. The multiple spindle chucking machine is similar to that of a multi-spindle automatic screw machine, except it is semi-automatic. Instead of bar stock, these machines are used for castings or forgings.

The multiple-spindle bar machine can perform side and end operations on each spindle simultaneously. The first spindle position feeds the bars of material out by an amount equal to the workpiece length plus the width of the cutoff tool. The last spindle position is the cutoff station. Independently operated attachments may be added to allow the operator to broach, burnish, hob, knurl, mill, slot, stencil, and thread.

Screw machine parts are integral components of a variety of products in the automotive, aerospace, communications, agricultural, medical, electronic, recreational, and ordnance for Defense industries. Screw machines are used to form turned parts for numerous computer products, hardware and tools, lawn and garden equipment and an endless array of other industrial products. Turned parts include fittings, screws, bolts, nuts, pins, rivets, fasteners, studs, bushings, shafts, plugs, pinions, pistons, washers and rings. Cost effectiveness, rapid production and close tolerances of large volumes of parts are a few advantages of screw machining. In addition, a wide variety of metals can be turned, including stainless steel, titanium and aluminum steel alloys, and non-ferrous metals including aluminum, brass, Teflon and others. Certain plastics can also be used in the production of screw machine parts.