What is CNC Machining?
CNC is the abbreviated term for Computerised Numerical Control. This is a computerised manufacturing process in which pre-programmed software and code operates production equipment. This equipment is often complex and includes grinders, lathes and turning mills.
As a subtractive manufacturing process, a range of tools are used to cut contours and shapes into a workpiece in order to create parts. The high level of automation means that CNC machining is suitable for both prototype and low-medium volume production.
A 3D model of the design is created using CAD software and is converted into a CNC programme. The machine is then programmed using the G Code, which informs the machine of precise measurements, such as speed, feed rate and coordination. The machine then removes material from the workpiece to produce the custom-designed part.
Many different types of materials can be CNC machined, including metals, plastics, glass, and foam.
Different Types of CNC Machining
The two main types of 3-axis machining are CNC milling and CNC turning. The chief distinction between the two is that CNC milling uses a rotating tool and CNC turning uses a rotating part.
Let’s now look at each of these methods in more detail:
During CNC milling, the cutting tool is attached to a spindle and can move in three different directions: along the X, Y and Z axes. It rotates at high speed to remove material from the workpiece.
Multi-axis milling allows 4 or more axes to provide added dexterity to the operation. 5-axis machines are commonly used and can create all kinds of parts within the accepted parameters of CNC milling.
CNC milling produces a flat or sculptured shape in the workpiece. The operation is performed on a milling machine using a multi-point cutting tool, also known as a milling cutter. The cutting tool cuts intermittently during the process.
CNC milling is ideal when straightforward cutting is required. However, for more complex geometries 3-axis CNC milling can have its limitations. As there are only 3 axes, the cutting tool may not be able to interrogate every part of the workpiece.
An advantage of this particular method is that parts can be produced to high tolerances and the setup costs are low.
For CNC turning, the workpiece is held in a chuck and rotated, and the tool is applied to the object piece to remove material. A stationary cutting tool is applied to the surface of the rotating bar stock, and unwanted material is removed. There can be several cutting tools used to achieve this.
Unlike with CNC milling, the tool does not rotate but moves around the workpiece radially and lengthwise. It is a highly accurate machining process which is suitable for achieving tight tolerances.
The speed of the cutting will be dependent on the type of machine, the material being used and the main features of the component.
The cutting tool remains in continuous contact with the workpiece for the duration of the process. It is performed using a single point turning tool, also known as an SPTT.
CNC turning machines are also known within the industry as lathes. The increased machining speed reduces manufacturing costs, improves lead times, and makes large volume production more viable. However, because it is only suitable for cutting cylindrical shapes, its geometries are limited. It is, therefore, more commonly used as a secondary step when an additional feature is required.
5-Axis machining (multi-axis machining) is a versatile process which provides more options and scope to the machining process than either CNC milling or CNC turning.
5-axis refers to the number of directions in which the cutting tool can move. It moves across the X, Y and Z linear axes, and rotates on the A and B axes. This means that it can approach the workpiece from any direction, thus adding greater versatility, accessibility, and sophistication to the process.
In essence, it means that a single component can be machined at 5 angles all at the same time.
There are savings to be made in terms of cost and lead times, and it is also possible to achieve more complex geometries than those which would be achievable with 3-axis machining.
This method also produces a smoother surface finish, and the accuracy of the final parts is usually high. The process is single setup, which also reduces the amount of manual labour required.
Advantages of CNC Machining
High level of automation which reduces the need for human input
Ideal for rapid prototyping, as parts can be produced very quickly
Ease of repeatability
Cost-saving exercise for prototyping or one-off designs, as there is no need to make custom tooling
Parts produced are often highly accurate and capable of achieving tight tolerances
CNC Machining by Industry
CNC machining is used for applications across a wide variety of business sectors. It is particularly useful in industries where a high level of precision and accuracy is required. Products and components which need to pass rigorous safety tests will significantly benefit from CNC machining.
Let’s take a look at the specific applications of CNC machining in some key business areas…
Automotive – gears, pins, brakes, shafts, valves, axles, and cylinder blocks
Aerospace – manifolds, bushings, landing gear and engine components
Medical – surgical instruments, dental implants, titanium joints and orthotics
Electronics – housings, computer motherboards, breaker panels, RFI shields and electrical insulation
CNC Machining at RP Technologies
CNC Machining is an element of our services here at RP Technologies which often gets forgotten, but we do in fact have extensive experience in this area, with excellent state-of-the-art CNC machining centres, a highly competent CAD design team, and a team of vastly experienced CAM engineers.
We precision machine components in most metals and polymers to support product designers and engineers for prototyping or low volume production. Our direct machining capabilities allow for fast turnaround of components, including those which feature complex shapes and contours.
Our CNC Machining department is expanding all the time. In 2023, we employed four new CNC Programmers and also invested in our brand new state-of-the-art Hurco 5-Axis Machining Centre.
We have received a high volume of repeat custom and we have also picked up many new customers during this period of time.
By offering tooling, moulding and CNC machining under one roof, we can reduce your total project costs by providing a one stop solution without the stress of sourcing multiple suppliers.