Since both NC and CNC machines are automated devices used for cutting and shaping metal, their principles are comparable. While CNC provides you more flexibility and ability to handle logical processes, NC allows you to store data while the machining process is being completed. Well, in this reading, I’ll be exploring what NC machining is, application, Types, diagram, advantages, disadvantages & how to use.
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What Is NC Machining?
Numerical control, also known as computer numerical control or CNC, is the automated computer-controlled operation of machining tools, including drills, lathes, mills, and 3D printers. Without a manual operator directly controlling the machining operation, a CNC machine follows a coded programmed instruction to process a piece of material (metal, plastic, wood, ceramic, or composite) to meet specifications.
A CNC machine is a computer – controlled device that can move its motorized tool and, more often, its motorized platform in response to precise input instructions. A CNC machine receives instructions in the form of a sequential program that is executed, including G-code and M-code for machine control. A human can write the program, but graphical computer-aided design (CAD) and/or computer-aided manufacturing (CAM) software generates it considerably more often. When using a 3D printer, the component that to be produced is “sliced” before the software or instructions are created. G-Code is used for 3D printers.
When compared to non computerized machining, which requires mechanical control via prefabricated pattern guides (cams) or manual control (e.g., using hand wheels or levers), CNC is a huge improvement. The design of a mechanical item and its production program are highly automated in contemporary CNC systems. Computer – aided manufacturing (CAM) software converts the mechanical dimensions of the product into manufacturing instructions. CAD software defines the part’s mechanical dimensions. The generated instructions are put into the CNC machine after being converted (by “post processor” software) into the precise controls required for a certain machine to make the component.
Since a given component may need for the use of many distinct tools, such as saws and drills, contemporary machines sometimes integrate numerous tools into a single “cell.” In some setups, the component is moved from machine to machine by a human or robotic operator using a variety of machines and an external controller. Either way, a highly automated set of procedures is required to make any item, and the end product nearly resembles the original CAD model.
John T. Parsons, a pioneer in numerical control, developed a machine tool that programmed to create a curve using milling cutters and coordinate movements. The idea was presented to the US Air Force in 1948, which funded several projects at the Massachusetts Institute of Technology’s (MIT) labs.
The makers of machine tools began working on commercial NC devices, and MIT demonstrated the first NC prototype in 1952. The researchers discovered Automatically Programmed Tools (APT) language, which allowed programmers to easily convey machining instructions to machine tools using English-like expressions. APT is still widely used in the industrial sector, with several contemporary programming languages built on its foundational ideas.
Numerical control technology finds its principal application in metal machining operations, such as turning, sawing, grinding, milling, drilling, and boring. This technology is designed to handle virtually the entire metal removal process, reducing costs and ensuring accurate results. However, it faces challenges such as costly job geometry, process errors, and potential engineering design changes. The principal application of NC technology is in series or sequence of machining operations, where high metal removal, 100% inspection, close tolerance, and batch processing are required. Future modifications in engineering design are anticipated.
How Does NC Machining Works?
Let’s break down the main stages of the NC machining process to understand how it works.
- Programming the Machine: Programming the machine with precise instructions is the initial state in NC machining. The machine is instructed on how to carry out the necessary tasks by these codes, which are often represented by G and M codes. Software for computer-aided design (CAD) and computer-aided manufacturing (CAD) may be used for this programming, guaranteeing accuracy in the instructions sent to the machine.
- Setting Up the Machine Tool: The machine tool is set up after the program is ready, this include setting up the required cutting instruments and fastening the workpiece position. To guarantee that the machining process runs smoothly and finished product fulfils the required criteria, the setup has to be precise.
- Executing the Machining Operation: The machining process may start after the machine is configured and the software loaded. When operating on operations like drilling, milling, or cutting, the NC machine adheres to the preprogramed instructions. High accuracy and reproducibility are made possible by the pre-defined instructions that govern every movement and operation.
- Inspecting the Final Product: The finished product is examined to make sure it satisfies the necessary requirements once the machining process is finished, measuring the part’s dimensions, looking for flaws, and confirming that it adheres to the design criteria are all possible steps in this examination.
The two major types of NC systems are contouring and PTP systems. Contouring systems depict the height and form of land surface on maps, providing topographical information for geography, landscape design, and surveying. They also control component motion, including moving velocity and planned routes between required places.
PTP systems regulate component positions by taking the shortest path and traversing at the machine tool’s permitted speed. Wireless point-to-point (PtP) systems enable bi-directional data transfer between two end points, providing a direct mode of communication. These systems offer reduced fixturing, greater manufacturing flexibility, reduced manufacturing lead time, non-productive time, reduced inventory, improved quality control, reduced floor space requirement, and reduced scrap.
However, NC systems have disadvantages such as the need for skilled operators, no optimal feed and speed, wear and wearing of punch tape components, and high investment and maintenance costs. Conventional NC machines do not provide an option to change cutting speed and feed during operation, leading to wear and less reliable components.
In conclusion, both contouring and PTP systems offer significant benefits in various industries, including geography, landscape design, and surveying. However, they also come with drawbacks, such as the need for skilled operators, unreliable punch tape components, high investment and maintenance costs, and potential for errors in programming.
