Computer numerical control (CNC) turning minimizes the opportunity for human error and is able to produce parts that have been machined with a margin of error of less than 0.001 inch.
Precision turned parts are cylindrical and machined from aluminum, titanium, brass, stainless steel, copper, polycarbonate, nylon and polyvinyl chloride (PVC). Though cylindrical, these parts have many variations; for instance, the general shape may be contoured, fillet, tapered or pointed. They may receive a smooth finishing or be given a textured surface. Precision turning is critical for many parts to guarantee that they fit together and will function correctly; in some applications, even a small flaw or error can throw off the whole system, wasting valuable time and money.
Parts that are machined to very precise specifications will perform to higher standards. The demand for top quality parts is high; precision turning is an important process for parts such as rods, shafts, hubs, pulleys, bushings, couplings, housing, flanges, nozzles, tools and more. Precision turned parts are used in applications across many industries including the automotive, commercial, electronics, petroleum, defense, aerospace, marine and construction industries.
Precision turning is a fairly simple process. Computer-controlled turning is performed in machine shops. A round, square or hexagonal blank called a workpiece is attached to spindles on the machine that hold it firmly in place. The blank begins to spin and as it rotates, multiple automated cutting, drilling, notching and knurling tools attached to the machine apply the appropriate amount of pressure to shear away the material. The tools are powered by a motor located at the machine’s base that acts as the power source for all operations.
These motors vary in horsepower in accordance with the size of the machine, the necessary speed and the material of the workpiece. Smoothing and finishing is completed and the part is removed from the machine. There is one major difference between turned and milled parts. During the machining process, turned parts are rotated and a stationary tool is applied whereas milled parts are held stationary while a tool rotates. There are two main pieces of equipment used to produce precision turned parts: screw machines or lathes. Both work in similar ways and are generally computer operated.
Screw machines have multiple spindles, which allows for the simultaneous machining of several parts. Lathes use a single spindle and a drill bit to cut away unnecessary material. CNC turning machines are quickly replacing conventional machines that require an operator with high levels of skill, knowledge and experience.