Understanding CNC Machining
Computer Numerical Control (CNC) Machining is a subtractive manufacturing process in which computers are used to control factory tools and machinery. This process is used to operate complex machinery, and CNC machines can complete third-dimensional cutting tasks with minimal human input.
The history of CNC Machines
CNC Machines had come a long way from the past when people built the first NC machines in the 1940s and 1950s. Early CNC machines were built on existing tools with modifications. The motors moved based on the information fed into the machines on punched tape where the operator manually punched the code.
How do CNC machines work?
CNC Machines are computerized machines that require human input. Files containing the information and instructions are uploaded into computerized machines such as G – Code and M – Code and then executed. A person can write the program, but in most cases, CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing) software is used to generate the program required. The motion is controlled in multiple axes, X-axis, Y-axis and Z-axis. Stepper motors or servo motors drive the position of the tool to make precise movements.
Types of CNC Machines
CNC Machines operate by the same principle. However, each machine functions differently based on its use. Some of the standard CNC Machines are listed below:
Water Jet Cutters
Water Jet Cutters are CNC Machines that use high pressure water to cut hard materials, such as granite and metal. The water is sometimes mixed with sand or other abrasive substances. This machine is usually employed in the manufacture of factory machine parts where materials are sensitive to heat.
Plasma Cutters are used on metals and some other materials. A plasma torch is present to generate the required heat and intensity to cut metals.
In Lathe machines, indexable tools and drills are generally used to make fast, high precision cuts while rotated. CNC Lathes produce complex designs which would not be possible in manually-run lathes.
These machines generally use G- Code or a unique language developed by a manufacturing team to move a workpiece across various locations and depths. Usage includes tapping, drilling, face milling, shoulder milling, and others.
CNC Electric Discharge Machines
Electric Discharge Machines (EDM) also includes Wire EDM and Sinker EDM. It is a manufacturing process where a component is placed under the wire, and the machine produces an electrical discharge where the heat of the discharge creates the desired shape. It is then flushed away with liquid to obtain the desired product.
It is also called wire cutting EDM. It uses spark erosion to remove parts from an electrically conductive material. A travelling wire electrode is used in this process, and so a new electrode is required every time the wire gets eroded.
A sinker EDM is also called a Volume EDM. It uses an inert anode and workpiece soaked in dielectric fluid. The materials are conducted with electricity to obtain the desired shape.