Common CNC precision machining methods
CNC machining is a general term used for a variety of machining applications. “CNC” stands for Computer Numerical Control and refers to the programmable capabilities of a machine that enables it to perform many functions with minimal human control. GC Machining is a world-class prototyping, precision CNC machining and lathe shop.
CNC machining is the use of CNC controlled machines to manufacture components. The term describes a range of subtractive manufacturing processes that remove material from bar stock or blanks to produce finished parts. There are 5 different types of CNC equipment that perform 5 common CNC precision machining operations.
CNC precision machining is widely used in medical, aerospace, industrial, oil and gas, hydraulics, and other industries. A variety of materials can be CNC machined, and metals, plastics, glass, composites, and wood can be machined.
Precision CNC machining offers many advantages over machining without CNC programmability. Significantly reduces machining cycle times, improves surface smoothness, and improves quality and consistency.
Here are the 5 most common precision CNC machining methods:
- CNC lathe processing
CNC lathes are characterized by their ability to rotate (turn) material during machining operations. The lathe’s cutting tool feeds in a linear motion along the rotating bar; this removes material around the circumference until the desired diameter and features are achieved.
A subset of CNC lathes are CNC Swiss lathes. Using a CNC Swiss lathe, the bar material is rotated and slid axially through the guide bushing into the automatic lathe, and then the cut parts are automatically processed. Generally speaking, CNC automatic lathes are suitable for processing small diameter parts.
CNC lathe machining can create internal and external features on parts: including drilling, broaching, reaming, grooving, tapping, and threading. CNC lathes and turning centers make components including screws, bolts, shafts, joints and more.
- CNC milling machine processing
CNC milling machines feature the ability to rotate the cutting tool while keeping the workpiece/piece of material stationary. They can produce a variety of shapes, including face milling (shallow, flat surfaces and cavities in the workpiece) and perimeter milling (deep cavities such as grooves and threads).
Parts suitable for production on CNC milling machines are typically square or rectangular shapes with various features.
3. CNC Laser Processing
CNC laser machines have a pointed router with a highly focused laser beam that is used to precisely cut, slice, or engrave materials. The laser heats the material and causes it to melt or vaporize, creating cuts in the material. Typically, the material is in sheet form. The laser beam moves back and forth across the material to create precise cuts.
This process allows for a wider freedom of design than traditional cutting equipment (lathes, turning centers, milling machines) and often produces cuts and/or edges that do not require additional finishing processes.
CNC laser engravers are often used to mark (and decorate) machined parts. For example, logos and company names are difficult to machine with CNC turning or CNC milling processes. However, it is so easy to engrave with a CNC laser that you can use laser engraving to add it to the component even after the machining operation is complete.
4. CNC Electrical Discharge Machining (EDM)
CNC electrical discharge machining (EDM) uses a highly controlled electrical spark to machine materials into the desired shape. It may also be called spark corrosion, spark machining, or wire burning.
A component is placed under the electrode wires and the machine is programmed to emit electrical discharges from the wires, generating intense heat (up to 11,700°C). The material is melted or washed away with liquid to create the desired shape or features.
EDM is most commonly used to create precise micro holes, grooves, tapered or angled features, and a variety of other more complex features in components or workpieces. It is typically used to machine difficult shapes and sizes, often in very hard metals. For example, gears.
5. CNC Plasma Cutting Machine
CNC plasma cutters are also used to cut materials. However, they do this using a high-power plasma (electron-ionized gas) torch controlled by a computer. Functionally similar to handheld pneumatic torches used for welding (up to 5500 degrees Celsius), plasma torches can reach temperatures up to 27500 degrees Celsius. The plasma torch melts through the workpiece to create cuts in the material.
Whenever CNC plasma is used for cutting, the material being cut must be electrically conductive. Typical materials are conductive metals such as steel, stainless steel, aluminum, brass and copper.
Precision CNC machining provides extensive production capabilities for manufacturing components and finishing. Depending on the environment of use, materials required, lead time, quantity, budget, and functionality required, there is usually a best approach that will provide the desired results.