What is CNC machining?
CNC machines make parts around the world for nearly every industry. They make things from plastic, metal, aluminium, wood, and many other hard materials. The word “CNC” stands for Computer Numerical Control, but today everyone calls it CNC. So, how to define CNC machine tools? All automatic motion control machines have three main components – the command function, the drive/motion system, and the feedback system. CNC machining is the process of producing parts from solid materials in different shapes using computer-driven machine tools.
CNC machines come in many types and levels of sophistication. Some machines can hold multiple tools simultaneously or work along the X, Y and Z axes to remove excess material from any side or angle.
CNC machining creates parts and assemblies for nearly every industry and application. This includes the aerospace industry and other highly complex industries that require the machining of large parts. Manufacturers can use this process on substrates such as:
- composite material
- Foam
- grass
- Metal
- plastic
- wood
CNC machining is particularly advantageous due to its automation capabilities. Automation enables machines to operate self-sufficiently, requiring less workforce to produce precise parts. The growing shortage of skilled machinists and labour in the industry has been a major factor in the advancement of CNC technology in recent years.
Generally, CNC machining refers to one of many reduction processes that remove material from a workpiece to complete a design. The CNC process uses computer control to handle the entire machining process from start to finish, resulting in consistently accurate parts. CNC machining equipment can follow the same set of instructions over and over to facilitate small or large production runs of the same parts.
Overview of the CNC machining process
The predecessor of CNC machining – numerical control (NC) machining – used punched tape cards and basic commands. CNC machining follows more complex commands and uses a greater variety of controls. These systems all direct cutting and forming tool removal, but CNC machining equipment can follow complex custom instruction sets from complex CAD or CAM designs.
Different CNC machining equipment can handle different tools, capabilities and operations. The CNC machining process usually includes the following general steps:
1. Design the CAD model
Before the CNC machining process begins, manufacturers must create product designs. Computer-aided design (CAD) software can be used to create detailed two-dimensional (2D) or three-dimensional (3D) models. These design files include parts geometry, dimensions and other technical specifications. The CAD software considers the machining process’s limitations and properties of the selected material.
For example, suppose the design contains holes formed by a cylindrical tool. In that case, the CAD software can notify the design engineer if the design is too complex for a given substrate or identify potential problems due to selected process constraints. These automated checks help CAD/CAM design services, and engineers avoid many potential errors during the rendering process, thereby increasing the efficiency of the prototyping phase.
2. Convert CAD files into usable CNC commands
These CNC-compatible instruction sets typically take one of two file types: STEP or IGES. They include programming languages such as G-code and M-code, each of which handles specific areas of machine function. G-code operations focus on the actual operation of the tools, such as their speed, the direction they move, and the distance they move. M-code operations focus on miscellaneous operations such as auxiliary functions such as power on and off.
3. Prepare the CNC machine
that machines cannot manage. This includes:
Load CNC program files into the machine
Add the workpiece to a mechanical spindle or vice so the machine can manipulate the workpiece
Install the specified machining tool
Check the work area, machine and workpiece
4. Execute the action
Once the equipment is ready, and the program is started, the CNC machining equipment executes these steps and performs machining operations on the workpiece. The program can complete the necessary restore process from start to finish without further operator input. After completing the instructions, the part can continue through the finishing and packaging process.
CNC machining by Elimold MANUFACTURING
1 – CNC Lathes and Lathes
CNC lathes and lathes are characterized by their ability to rotate (turn) material during machining operations. The cutting tools of these machines are fed in a linear motion along the rotating bar; the material is removed on a circumference until the desired diameter (and feature) is achieved.
A subset of CNC lathes are CNC Swiss lathes (this is the type of machine the Pioneer Service operates). With a CNC Swiss lathe, the rod of material rotates and slides axially into the machine through a guide bush (a retaining mechanism). This provides better support for the material as the die machined the part’s features (resulting in better/tighter tolerances).
CNC lathes and lathes can create internal and external features on components: drills, holes, broaches, reams, grooves, taps, tapers, and threads. Components manufactured on CNC lathes and turning centres include screws, bolts, shafts, poppets, and more.
2 – CNC Milling Machine
CNC milling machines can rotate the cutting tool while keeping the workpiece/block of material stationery. They can produce a variety of shapes, including face-milled features (shallow, flat surfaces and pockets in the workpiece) and peripheral-milled features (deep pockets such as slots and threads).
Parts produced on CNC milling machines are typically square or rectangular shapes with multiple features.
3 – CNC Laser Machine
CNC laser machines have a pointed router with a highly focused laser beam for precisely cutting, slicing or engraving materials. The laser heats the material and causes it to melt or evaporate, creating cuts. Typically, the material is in sheet form, and the laser beam is moved back and forth across the material to create precise cuts.
Compared to conventional cutting machines (lathes, turning centres, milling machines), this process can produce a wider range of designs. It often produces cuts and edges that do not require additional finishing processes.
CNC laser engravers are often used for machined components’ part marking (and decoration). For example, it isn’t easy to machine logos and company names into CNC-turned or CNC-milled parts. However, it can be added to components using laser engraving even after the machining operation is complete.
4 – CNC Electric Discharge Machine (EDM)
A CNC electrical discharge machine (EDM) uses a highly controlled electrical discharge to machine material into the desired shape. Also known as spark erosion, die, spark machining or wire burn.
An assembly is placed under the wire, and the machine is programmed to emit an electrical discharge from the wire, which produces intense heat (up to 21,000 degrees Fahrenheit). The material is melted or washed away by the liquid to form the desired shape or feature.
EDM is most commonly used to create precise micro-holes, grooves, tapered or sloped features, and a variety of other more complex features in components or workpieces. It is typically used for very hard metals that are difficult to machine into the desired shape or feature. Typical gears are a good example.
5 – CNC Plasma Cutter
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. Similar in function to hand-held pneumatic torches for welding (up to 10,000 degrees Fahrenheit), plasma torches can reach up to 50,000 degrees Fahrenheit. The plasma torch melts through the workpiece to create cuts in the material.
As a requirement, whenever CNC plasma cutting is used, the material being cut must be conductive. Typical materials are steel, stainless steel, aluminium, brass and copper.
Precision CNC machining provides a wide range of production capabilities for components and finishing in a manufacturing environment. Depending on the usage environment, required materials, lead time, quantity, budget, and required functionality, there is usually an optimal method to deliver the desired results.
With enough time, resources, and imagination, manufacturers can automate almost any process. Raw materials can go into the machine, and finished parts can be packaged and ready. Manufacturers rely on various CNC machines to manufacture products quickly, accurately and cost-effectively.