- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 14 Feb 2019
Computer numerical control
Computer numerical control (CNC) is the digital manipulation of machines such as drills, lathes and other machine tools by computers and circuitry. Also known as numerical control or computational numerical control, the process comprises a series of numerical values generated by a computer; each of which is assigned to a desired tool or control position to enable the machining of a blank piece of material to precise specifications without requiring a manual operator.
The process dateso back to the first CNC machines built in the 1950s and 60s which relied on punched tape (or perforated paper tape) to communicate the tool position that was controlled by a motor. The process has since been refined and improved by analogue and digital computers.
Under CNC, every object to be manufactured is allocated a G-code (an international standard language) that is stored in the machine and executed by a microcomputer (machine control unit or MCU) attached to the machine. The G-code is a set of instructions – such as the positioning or speed of the tool’s components – that the machine will follow to create or part-create the item in question. Typically, this allows the automation of machine tools such as lathes, mills, routers, lasers and grinders.
In sophisticated manufacturing operations, G-codes are typically derived from the automatic translation of engineers’ CAD drawings into a sequential programme of machine control instructions which are then implemented. A less complex method is writing part-programmes using high-level, part-programming languages.
CNC does not rely on conventional control by cranks, cams and gears. Instead, it allows desired feed rates and cuts to be ‘dialled in’, thereby providing precise, repeatable machine movements that can be optimised for speed, feed and machine cycles.
 Benefits of computer numerical control
- Provides highly automated, precise manufacturing;
- Does not rely on manual control;
- The part produced is a close match to the original CAD drawing, and
- Gives flexibility of batch size.
- 3D printing
- Water jet cutters, drills, embroidery machines, sheet metal works and glass cutting
- Electrical and/or chemical machining
- Lasers, oxy-fuel and plasma technology
 Related articles on Designing Buildings Wiki
- 3D printing.
- Advanced construction technology.
- Building drawing software.
- Building information modelling.
- Common data environment.
- Computer aided design.
- Computer aided manufacturing.
- Computers in building design.
- Computers in tendering.
- Computers in the management of construction.
- Information manager.
- Information and communications technology.
- PAS 1192-2:2013.
- Rapid prototyping.
Featured articles and news
We have a great range of introductory articles written by ECA.
7 of the most common myths, busted.
Consider a career in the electrotechnical industry.
Exploring local assets of community significance. Book review.
Wood-burning stoves should not be used in thatch-roofed buildings.
Servitisation, smart systems and connectivity.
What happens to the Construction Products Regulation if there is no Brexit deal.
The first step to long-term prosperity.
The status and rights of employees in construction
Continuing to share environmental best practice.
The employee assistance programme EAP.