What are CNC Machines? A Beginner's Guide

3D printers are widely used computer-controlled manufacturing machines, although they are generally discussed separately from CNC machining equipment. They follow a prepared build file that directs the printing process, including motion and material deposition or curing, depending on the technology.

3D printers work through an additive manufacturing process, where material is added (layer by layer) to create our parts. Two benefits of this production technique are that there is little waste, and that complex geometries can be manufactured depending on the resolution of the 3D printer being used.

There are many different types of 3D printers out there, some that extrude rolls of material called filament, and others that cure liquid resin using a light source. Some 3D printers are more affordable, and some can produce higher quality and stronger parts. 3D printers typically manufacture parts using some type of plastic or plastic composite, though versatile material options are becoming more readily available as this technology improves.

CNC Milling Machines are one of the most commonly used CNC machines in an industrial setting, as well as for hobby and prototyping use. Milling machines utilize a milling spindle that rotates a cutting tool at high speeds, and then uses this cutting tool to carve material through a subtractive manufacturing process.

Unlike an additive process, subtractive manufacturing requires us to start with a raw piece of material such as aluminum or wax - then uses milling operations to create pockets, contours, holes, and other types of engravings or cuts to fabricate our designs.

CNC Mills come in many different configurations, from smaller desktop units to large industrial machines. Mills are also typically more versatile than other CNC machines, with some mills being able to manufacture parts out of metals, plastics, composites, and woods - like the Carvera and Carvera Air. The complexity of the parts you can create depends on the mill’s motion capabilities, power, and overall design. Tool access, cutter geometry, machine rigidity, and workholding also affect which features can be machined successfully.

CNC routers are similar to CNC milling machines because both use rotating cutting tools to remove material. Routers often use high spindle speeds for cutting wood, plastics, and other sheet materials, while mills are commonly designed around greater rigidity and the cutting demands of metalworking. Spindle speed alone does not distinguish the two.

Many CNC routers offer a large working area and are used for signs, furniture components, panels, and relief carving. Prices, enclosure designs, and material capabilities vary considerably between machines. Precision depends on the machine’s construction, drive system, spindle, tooling, and workholding, so it should not be judged from the “router” or “mill” label alone.

A CNC lathe is another machine that operates through a subtractive manufacturing process. In conventional turning, the workpiece rotates on a spindle while a non-rotating cutting tool moves along or across it to remove material. Some CNC turning centers also include live tooling, which allows rotating tools to perform operations such as milling, drilling, and tapping.

Turning is especially useful for parts with features arranged around a central axis, such as shafts, bushings, spindles, and threaded components. CNC lathes can produce these features efficiently, with the achievable geometry and production rate depending on the machine, material, tooling, and setup.

A rotary axis on a CNC mill can help machine features around a part and produce some shapes that resemble turned components. However, rotary milling is not the same process as turning on a lathe: the cutting motion, workholding, and production efficiency differ.

CNC Lasers also come in many forms, and like a CNC Mill or Router, we start with a piece of raw material. All lasers then use a light source to cut or engrave materials, typical wood, fabric, or plastic.

Laser capability depends on wavelength, optical power, operating mode, and material compatibility. Blue-light diode systems can engrave and cut certain compatible materials, but they cannot directly cut clear acrylic effectively. CO₂ lasers are commonly used for materials such as wood and acrylic. Fiber laser systems are widely used for metal marking or cutting, although a marking machine and a sheet-metal cutting machine have different capabilities. Always check the specific machine’s supported materials and thicknesses.

But a key safety concern that you must consider with lasers is ventilation, as all laser cutters and engravers release harmful fumes as a byproduct of this manufacturing process. As such, it's important to ensure you're working with materials that are safe to use for a laser, and also have proper exhaust and air filtration systems in place.

Axis count describes a machine’s motion capabilities rather than a separate manufacturing process. The following examples refer to common milling and routing configurations; other CNC machines can use different axis arrangements.

On a typical vertical 3-axis mill or router, X and Y describe movement in the horizontal plane, while Z describes movement along the vertical spindle direction. A 4-axis configuration adds a rotary axis, often an A-axis that rotates the workpiece. A common 5-axis milling configuration adds two rotary axes, allowing the tool and workpiece to approach one another from more directions. For beginners learning milling, three axes are often a practical starting point.

Rotary axes may reposition the workpiece between cuts or move during cutting, depending on the machine, controller, and CAM software. Having more axes does not automatically mean simultaneous multi-axis machining.

There are many other types of CNC machines out there, some which are suitable for hobby and DIYers like vinyl cutters or embroidery machines, and others which are used in industrial settings like waterjet cutters and wire EDM machines.

Across these machines, a shared principle is the use of programmed instructions to coordinate motion and machine functions. Many designs use linear guides and stepper or servo drives, but the mechanical arrangement and motion system vary with the process.

What makes the machine unique are the types of control systems that are used, as well as the tool head. For example 3D printers are sometimes built similarly to laser cutters or mills, but one has an extruder while the other has some type of spindle or laser module. This is why you can often find versatile machines that can perform many different operations, like the Carvera and Carvera Air desktop CNCs.