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.
Let’s Get Started!
Contents
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.
Brief History Of The NC
John T. Parsons made significant contributions to the field of numerical control in 1940 when he attempted to automatically create a curve using milling cutters and coordinate movements. Parsons developed the idea of controlling a machine tool using punched cards that included a coordinate position system in the late 1940s.
The machine was programmed to provide the required finish by moving in tiny increments. Parons presented this idea to the US Air Force in 1948, and the Air Force funded a number of projects at the Massachusetts Institute of Technology’s (MIT) labs. The makers of machine tools soon started working on their own to get commercial NC devices into the market.
Following extensive study, MIT was able to display the first NC prototype in 1952 and illustrate the technology’s potential uses the following year. The investigation went on as researchers at MIT discovered Automatically Programmed Tools, or APT language, which could be used to program the NC machines.
The primary goal of the APT language was to provide programmers a way to more easily convey machining instructions to the machine tools using English-like expressions. APT is still extensively used in the industrial sector, and several contemporary programming languages are built on its foundational ideas.
Application of Numerical Control Technology
Numerical control technology has applications in a wide variety of production operations such as metal cutting, automatic drafting, spot welding, press working, assembly, inspection, etc.
However, NC finds its principal application in metal machining operations. It is built to do virtually the entire metal removal process. (Example for metalworking Turning, sawing, Grinding, Milling, Drilling, boring).
These are the production jobs where the numerical control machines are most appropriate are listed below.
- The NC technology may be used in a series or sequence of machining operations.
- The job geometry is costly and difficult.
- Process errors cause significant loss.
- Future modifications in engineering design are anticipated.
- High metal removal is necessary.
- The work piece needed to be inspected 100%.
- Close tolerance is required on the work portion.
- While processing calls for a large number of procedures.
- Small lot sizes are often processed in batches.
Types of NC System
These are the two major types of NC System, let explain the two major types
1. Contouring System
The process of using contour lines to depict the height and form of the land surface on a map is known as a contouring system. The peaks, valleys, and slopes of the landscape may be understood thanks to these lines connecting sites of similar height.
Given its ability to graphically convey topographical information, this approach is vital in the fields of geography, landscape design, and surveying. In addition to managing locations, contouring NC systems may also control component motion, which includes moving velocity and the planned route between the required places.
2. PTP System
PTP is an NC system that alone regulates the component positions the component motion’s course in relation to the workpiece is not regulated in this system. Traveling between several points is done 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. Point-to-point (P2P) systems are often used when two line-of-sight (LOS) endpoints need to communicate quickly, continuously, and impenetrably.
Diagram
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.
Advantages Of NC System
- Reduced fixturing. The fixture required in NC operation are simpler and less costly because NC tape does position instead of jig and fixture.
- Greater manufacturing flexibility. Changes in the engineering design and a modification in the manufacturing schedule are readily accommodated by NC.
- Reduced manufacturing lead time. The project can easily and fast set up with NC.
- Reduced non-productive time. When it comes to intricate machining, NC seems to be useful in cutting down on idle time, due to quicker setup times, quicker/automated tool changes, and shorter workpiece handling times.
- Reduced inventory. This is the result of fewer setup reduced lead time.
- Quality control improved. No chance of errors made by people, it makes the component very precisely, it also lowers the inspection man-hour.
- Reduced floor space requirement. since the one NC can do variety of operation it replaces several conventional machines.
- Reduce the scrap. the high accuracy of NC machine helps to reduce scrap material.
Disadvantages Of NC System
- Require skilled operator. Finding and training of NC personnel should be considered.
- No optimal feed and speed. Conventional NC machine do not provide an option to change the cutting speed and feed during the operation.
- Tearing and wearing of punch tape and less reliable punch tape component, part programming mistake in punched tape.
- High investment cost and Maintenance cost. The majority of advanced and complicated technologies are more expensive than traditional machines.
- The majority of advanced and complicated technologies are more expensive than traditional machines.