Many people have heard of CNC, but do not know what it stands for. It is a technology that has revolutionised the manufacturing industry as CNC machines are able to create parts with incredible accuracy and speed.
If you are interested in learning more about this technology, keep reading! We’ll not only take a look at what it stands for but also how it works along with its pros and cons. Let’s get started!
What Does CNC Stand For?
CNC stands for computer numerical control and is a term referring to automated specialised machinery that is sometimes called machining centres. It’s a process for automating the control of machine tools via software installed in a microcomputer linked to a tool. It is often used in manufacturing for machining plastic and metal parts.
With CNC, each created item gets a distinct computer program usually written in a G-Code, an international standard language.
The program consists of parameters and instructions the machine tool needs to follow. These include the material feeding rate and speed/positioning of tool components.
CNC Machining
It is a subtractive manufacturing process involving the use of cutting tools. These are utilised to remove materials (as necessary) to create the desired part.
The process contradicts 3D printing, which is an additive manufacturing technology wherein materials are added layer by layer to create a part to the required form. The process is opposed to that of CNC where you’ll take the material from a blank to produce it.
Before there was any form of automated control of machining, the production of a custom machined part was done manually. Usually, the process was done on a milling machine or lathe by a machinist.
To get the job done, highly-skilled operators were needed to read blueprints and take precision measurements. They had to utilise instruments such as micrometres and callipers to repeatedly cut at a workpiece. This occurred until a finished portion with the right dimensions was created.
The more complex the design and the higher tolerance required, the more tedious the machining process. This, however, limited the throughput and impacted costs.
With that, steps to include automation in the process started becoming more important for projects involving the creation of precise components.
The Basic Steps in CNC Machining
To give you an idea, here are the basic machining steps:
- Design and creation of a CAD model of the chosen part
- Going through a conversion process to take the CAD model details and produce a CNC program
- Proceed with the set-up/initialisation of the CNC machine
- Run the saved program to perform machining operations
How Does CNC Work?
Since we’ve answered the question of what CNC stands for, let’s discuss how it works. Early in the process, engineers produce a CAD (or computer-aided design) drawing of the part they want to be manufactured. From there, they convert the drawing into a G-code.
The program is then loaded to the machine control unit (MCU) and an operator does a test run without the raw element in place. They do this to ensure adequate performance and positioning. This is a vital step because incorrect positioning or speed can damage or impair the machine and the part.
CNC is known to offer more complexity and precision than manual machining. Other benefits are greater flexibility, speed, and contour machining. The latter allows the milling of contoured shapes including shapes produced via 3D designs.
However, CNC can be quite pricey and need more maintenance than other production processes. Also, it may force companies to get a skilled CNC programmer to get the job done right.
A few CNCs are built-in with CAD and CAM (computer-assisted manufacturing) software. These can help boost MCU's programming process.
Coupling with ERP software and other related applications like enterprise asset management software can help improve plant performance & maintenance. Plus, it can also facilitate operating intelligence methods.
Advantages and Disadvantages of CNC Machines
Here are the advantages and disadvantages of using CNC machines.
Advantages
- Accurate with high precision
- Less time consuming
- Safer to use and operate
- Minimal staff required
- No possibility of human error
- Reliable and complex designs can be produced
- Low maintenance and highly versatile
- Can work 24 hours a day
- Generated waste is lower compared to conventional machining
- Efficient and fast
- No need for product prototyping
- It can work with various materials
Disadvantages of CNC machines
- Expensive
- Operators need to be trained to operate the machine
- During breakdowns, a skilled professional has to solve the issue
- Installation is complex
History and Evolution of CNC
The theory of CNC machining did not start how most people assume it did. Today when we mention CNC machining, people expect computerised methods. However, CNC machining started out as a more manual copying method.
In 1949, the very first machine was credited to James Parsons, a computer pioneer. He worked on an Air Force research project related to producing helicopter blades and improved aircraft skin.
He successfully calculated helicopter airfoil coordinates via an IBM602-A multiplier. From there, Parsons entered the information into a punched card that he utilised on a Swiss jig borer. The data led to the creation of tons of aircraft skins and helicopter blades.
Development of CNC
Before creating the first CNC machine, other devices were instructed to create other tools. These were called NCs or Numerical Controls. Eventually, Parsons created the first CNC machine, and with this came an evolution. Here is a quick timeline of the evolution and progress of the CNC machining history.
1952 - 1958 - The Cold War intensified, leading to the need for enhanced efficiency and productivity in the creation of many weapons and machines. So in 1952, the first CNC milling machine called Cincinnati Milacron Hydrotel was created by Richard Kegg together with MIT. In 1958, Kegg eventually filed a patent for the MCA for a Positioning Machine tool.
1967 - 1972 - More people worldwide started recognising CNC machining because of the CAD and CAM development in 1972. The inclusion of these in CNC machining led to its great development. Despite this, CAD and CAM were not regarded as a regular part of the manufacturing method.
1976 - 1989 - Then in 1976, 3D CADs and CAMs were introduced and included in CNC machining. Then in 1989, CAM and CAD software-controlled machines started becoming the industrial standards for CNC machines.
Final Thoughts
Computer numerical control has become an important way to make a wide variety of items quickly and efficiently. It has come a long way since the days of James Parsons with thousands of companies around the globe now using CNC.