In 1949, the first CNC machine was invented. Since then, CNCs have evolved rapidly changing industries and manufacturing forever.
Depending on your budget, time, work material, shape, and size of the product, you can choose from several types of CNC machines to make almost anything you want.
There are eight types of CNC machines: CNC Mills, CNC Routers, CNC Plasma Cutting Machines, CNC Lathes, CNC Laser Cutters, CNC Water-jet Cutters, CNC Electrical Discharge Machines (EDM), and CNC grinders.
|Types of CNC Machines|
|1.||CNC Milling Machine|
|3.||CNC Plasma Cutting Machine|
|4.||CNC Lathe Machine|
|5.||CNC Laser Cutting Machine|
|6.||CNC Waterjet Cutting Machine|
|7.||CNC Electrical Discharge Machine|
Different types of CNC Machines
Different types of CNC machines
CNC machines can be differentiated based on the function they perform, the materials they work on, and the underlying technology of the machine.
But how many types of CNC machines are there?
In the next sections, I give a broad overview of each type of CNC machine.
1. CNC Milling Machine
CNC mills are one of the most popular CNC machines, used mainly for milling, drilling, and cutting operations.
Mills derive and convert specific programs made up of letters and numbers (G-code) in order to route and path the spindle in different ways.
After placing the workpiece inside the milling machine, the computer takes control.
The computer code guides and instructs every movement and action of the spindle and tools to cut and convert the workpiece to a designed custom part with high accuracy.
Tapping, Drilling, Turning, Face milling, and Shoulder milling are some of the common functions that a CNC milling machine can perform.
CNC Milling machines have configurations starting from 3 axes, up to 6-axis.
In the most basic 3-axis CNC, the three axes represent the X-axis (left-right), Y-axis (front-back), and Z-axis (up-down) movements.
CNC milling machines are quite large and expensive when compared to other CNC machines like CNC routers.
In general CNC Mills are used to machine hard metals and CNC routers are used to machine softer materials like wood, plastics, and some soft metals.
Okuma, Haas, and DMG Mori are some of the popular professional-level CNC milling machine manufacturers.
2. CNC Router
A CNC router is a machine similar to a CNC mill but is generally used for machining softer materials and is typically less precise compared to CNC Mills.
CNC Routers are significantly cheaper than CNC Mills.
A professional-level CNC Router can cost less than $2,000 whereas even entry-level CNC Mills cost upwards of $10,000.
CNC routers are characterized by their ability to use computer numerical control to route spindle and machine tool paths to design and shape materials like wood, steel, composites, aluminum, foam, and plastic, into the desired design and shape.
CNC Routers generally consist of a Mechanical Base, Spindle, Stepper motors, Stepper Drivers, Controllers, and Power Supply.
When compared to traditional machining techniques, CNC routers reduce wastage, increase productivity and accuracy in addition to producing products at a faster rate.
Like CNC Mills, CNC routers are also available in various axes ranging from three to six.
Generally, entry-level CNC routers consist of a 3-axis system to carve the workpiece into the desired shape, with a rotary tool attachment (4th-axis), which can be purchased separately to machine curved workpieces.
Some of the most popular CNC router brands on the market today are Carbide 3D, Inventables, Avid CNC, BobsCNC, and Onefinity.
3. CNC Plasma Cutting Machine
CNC plasma cutter is a CNC cutting machine, similar to CNC milling machines in the fact that they share the same function, that is to remove material to produce the desired cut.
However, CNC plasma cutting machines use a plasma torch to cut through the workpiece while a milling machine uses an end mill or router bit attached to a spindle.
CNC plasma cutters work on the electric discharge mechanism, and therefore, can only be used for machining electrically conductive materials. This could also be considered a disadvantage of plasma cutting.
Typical materials used as workpieces for plasma cutting are brass, copper, aluminum, steel, and stainless steel.
A CNC plasma cutting machine is equipped with a high-powered torch that is able to cut through even the toughest materials like titanium and steel.
Primarily CNC Plasma cutters are used in heavy industries like shipbuilding, automobile manufacturing, chemical manufacturing, and industrial steel construction sites.
Consequently, the workpiece is generally large and heavy in CNC plasma cutting.
In a CNC plasma cutting machine, the torch is produced by passing high-velocity gas through a nozzle.
While this process is carried out, an electric arc is produced.
The arc forms through the high-velocity gas and jumps onto the material being cut, converting an amount of the high-velocity gas into plasma (electronically ionized gas).
CNC plasma cutting machine exhibits a close resemblance to the function and property of a handheld gas-powered torch.
While the gas-powered torch produces temperatures up to 10,000 ℉ for welding, plasma torches achieve temperatures ranging from 10,000 ℉ to 50,000 ℉.
The material being cut melts at this temperature due to the amount of heat produced.
Some of the popular CNC machine brands that manufacture CNC plasma cutters are STV CNC and Torchmate.
An entry-level plasma cutting CNC machine will cost around $5,000, while the most expensive ones cost hundreds of thousands of dollars.
4. CNC Lathe Machines
CNC lathes work by spinning the workpiece at a high speed while a cutting tool is applied to the surface to produce the desired product.
Lathes, typically work best for products with cylindrical, conical, or flat shapes. This is a distinct difference between CNC Mills and Lathes because CNC Mills can work on any shape.
Although considered to be less precise and versatile compared to a CNC Mill, CNC Lathes cost lesser and are excellent for quick, simple jobs.
CNC lathes gain an advantage in the fact that the machine is smaller and more compact, thereby increasing its portability.
The machine is also characterized by its ability to rotate the workpiece while in operation.
CNC lathe machines consist of a computer-controlled lathe spindle that rotates and turns the raw materials into position as programmed and commanded by the computer.
Typically, CNC Lathes have two axes. The Z-axis is the movement of the cutting tool along the length of the workpiece, and the X-axis controls the movement of the cutting tool perpendicular to the chuck.
The movement along the X-axis determines the depth of the cut and controls the diameter of the workpiece.
Although CNC lathes with higher axis systems are available on the market, the 2-axis is the most basic form of lathes.
The tools used for cutting the workpiece are fed in a straight or linear path along the spinning or rotating bar stock.
The machine then applies a subtractive method, i.e., it removes material around the circumference of the material until the desired diameter for the custom design is achieved.
Since the machine has the feature to rotate the raw materials, it requires fewer axes for the movement of the lathe cutting tool, leading to their smaller form factor.
CNC lathe machines are mainly used for their ability to create external and internal features on the workpiece by performing different operations, such as turning, drilling, boring, threading, etc.
CNC Lathe machines are similar in how they are controlled to CNC mills and can read both G code and proprietary programming languages.
Shafts, bolts, and screws are some of the components made on CNC lathes and turning machines. Some of the popular manufacturers of CNC Lathes are HaaS, Okuma, DMG Mori.
5. CNC Laser Cutting Machine
CNC laser cutters resemble CNC plasma cutters in their ability to cut through tough materials.
However, a CNC laser cutting machine uses a powerful beam of highly focused laser to perform the task, unlike a plasma cutter which uses plasma (ionized gas).
Since lasers have a smaller point of contact and spread when compared to torches, CNC laser cutting machines typically provide a higher level of accuracy and a better surface finish when compared to CNC plasma cutters.
Also, CNC laser cutters are comparatively more expensive than CNC Plasma cutters of similar capability (accuracy and cutting depth).
Laser cutters offer greater material flexibility than plasma cutters and are predominantly used for cutting plastic, paper, fabric, metals, and hardwood.
Depending on the density and strength of materials, the laser intensity can be tweaked to cut through the material easily.
In CNC laser cutters, the workpiece (generally a flat surface) is placed on the work table.
The laser beam then moves to and fro on the material, producing the heating effect to vaporize or melt the workpiece and create the required cut.
CNC laser cutters are often able to produce a variety of designs when compared to other cutting machines.
Often, the cuts and edges produced are so precise and clean that they do not require additional finishing.
Hence CNC laser cutters and engravers are often used for making and engraving machine components.
Laser engraving is highly used in decorative works such as sign-making, woodworking art, and glass engraving.
CNC Laser cutting is opted for when the tolerances are tight and a precise output is required.
Lasers such as CO2 and neodymium (Nd)-doped yttrium-aluminum-garnet (Nd:YAG) are commonly used in CNC laser cutting machines.
Some popular CNC laser cutter brands are OMtech, Flux Beamo, and Glowforge.
6. CNC Waterjet Cutting Machine
CNC Waterjet cutters, as the name suggests, use high-pressure jets of water to cut through materials.
Typically CNC Water-jet Cutting is opted for when the material to be worked upon is sensitive to temperature and could melt at high temperatures, such as plastic and aluminum.
Although these machines can cut with just water, usually additional abrasive materials like garnet (a mineral) or aluminum oxide are added to the water for more efficient cutting.
A CNC Water-jet cutting machine costs more than a plasma cutter with similar specifications. But it costs less compared to a CNC Laser cutter with similar specifications.
One disadvantage of a CNC water-jet cutter is that it is typically slower than CNC plasma cutters and CNC laser cutters.
Some popular CNC waterjet cutter brands are KMT, WARDjet, OMAX, and Flow.
7. CNC Electrical Discharge Machine
CNC Electrical discharge machines (EDM) are also termed spark CNC machines.
The process in an EDM can also be called wire burning, die sinking, sparks machining, or spark eroding.
CNC electric discharge machines use electrical sparks which produce high temperatures to manipulate and shape materials into the desired form.
Electrical discharge CNC machines produce a series of controlled sparks or recurring electrical discharges producing temperatures up to 21,000 ℉ to vaporize the material and produce the desired shape.
The materials or workpieces are placed in between two electrodes, the top, and bottom electrodes.
Based on the G code, the computer instructs the amount of electrical discharge that must be produced by the electrodes.
This process creates sparks that consume the material on the workpiece as per the design.
The materials consumed by the sparks are flushed/washed by a dielectric fluid which completes the process.
Electrical Discharge Machine is distinguished by its ability to create precise slots, micro holes, angled or tapered features, which are usually difficult to machine using traditional CNC methods.
Since EDM uses sparks for cutting rather than bits or end-mills, the machining in an EDM is non-contact.
As a result, it is suitable for machining thin workpieces, which otherwise would undergo deflection when acted upon by the cutting force.
CNC Electric discharge machining is used for machining complex designs with very high precision, such as sprocket gears.
Kent USA is a popular brand in the USA that makes Electrical Discharge Machines (EDM).
8. CNC Grinder
A CNC Grinder uses abrasive tools to smooth and finish a machined product.
Grinders are typically used in applications requiring extremely high precision such as engine parts.
Generally, the product is first created with a rough surface using a CNC Mill or Lathe and then moved to the CNC Grinder for grinding operation to attain the final finishing.
CNC Grinders come in various types such as surface grinders, roll grinders, and cylindrical grinders among others.
There is a lot of variety in the type of abrasive used for grinding as well, such as plated or vitrified CBN, Diamond grinding wheels, Aluminum Oxide, and Ceramic Blend Grinding Wheels among many others.
Selecting the Best CNC Machine for Your Application
The selection of the machine depends upon the shape of the workpiece, the type of material, the accuracy required, and the machining operation to be performed.
Generally, a CNC router is used for cutting and carving soft materials like wood, plastics, PCB, etc., whereas a CNC mill is suitable for machining hard materials like metals.
Similarly, a CNC lathe is recommended for machining axisymmetric workpieces, like furniture legs, shafts, and other cylindrical workpieces.
A CNC laser cutter is recommended for applications where high accuracy and intricate patterns are to be cut or engraved on a workpiece.
Although a CNC electrical discharge machine or a waterjet machine can provide better accuracy, they are comparatively slower than laser cutting and are preferable where high accuracy is preferred over machining time.
On the other hand, a plasma cutter provides comparatively lower accuracy than a laser cutter but is best suited for cutting thicker metals, which otherwise can be difficult to machine with a laser cutter.
The machines discussed above are the most common types of CNC machines that are in use today.
Apart from these 8 CNC machines, there are other machines such as CNC machines with automatic tool changers, which are upgraded versions of these machines and include an ATC to automatically replace the cutting tool during machining.
Moreover, these machines are also available in 5-axis and 6-axis variants that provide greater flexibility to perform complex machining operations with relative ease.
However, these upgraded variants are very expensive and are only suitable for large-scale industrial applications.
The choice of machine depends on the type of job, the accuracy required job budget, and the time available to complete the job.
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