CNC machines are electro-mechanical devices that can manipulate tools around a varying number of axes, usually 3 or 5 axes with high precision, per instruction from the computer program.
Types of CNC machines are classified according to the two manufacturing process i.e subtractive manufacturing process and additive manufacturing.
Subtractive manufacturing process
CNC machines using subtractive manufacturing methods employ tools to remove layers of material from a stock-piece usually known as blank or workpiece to convert them into the desired finished product.
Additive manufacturing process
CNC machines based on additive manufacturing method use the material from which the desired product is to be made instead of a tool for removing material. In additive manufacturing technique layers of material are added until the desired finished product is obtained.
Now that we know the two manufacturing process, let’s see the different types of CNC machines and their application based on these two manufacturing techniques.
Types of CNC machines
CNC milling machine
CNC milling machine most commonly used manufacturing machines which employ rotating multi point built-in tools for drilling and cutting. Milling machines work on programming employed for it based on G-codes or other codes generated using CAM (Computer-aided manufacturing) software, to guide the tools to drill or cut the material. Basic CNC milling machines consist of a three-axis system ( X, Y and Z), the many modern mills also use additional axes.
Advantages of CNC milling machine
- Rapid turnaround
- Custom finishes
- Material compatibility
CNC lathe machine
CNC lathe machines are distinguished by their ability to cut pieces in a circular direction with indexable tools. The cuts applied by CNC lathes are carried out with extreme precision and high velocity. The material is fixed to a spindle which rotates at high velocity and it is pressed against a carving tool that gives it the desired shape. A basic lathe consists of only two axes (X and Z) which makes it smaller and compact. Similarly, like CNC milling machines, lathe machines can be operated by G-codes or unique proprietary codes.
Advantages of CNC lathe machine
- Well finished products
- Reduces time consumption
- Low maintenance
- Easy upgradation
Plasma cutting machine as the name suggests uses a powerful plasma torch to cut the material. Plasma cutters are mainly used to cut metal sheets or plate but can also be used to cut other materials. A combination of compressed gas and electric arcs is used to generate the plasma to achieve the required speed and heat necessary to cut the metal. Unlike electric welding machines which can achieve temperatures up to 10,000 degrees Fahrenheit, plasma torches can achieve temperatures of up to 50000 degrees Fahrenheit.
Advantages of Plasma cutting machine
- High cutting speeds
- Wide cutting area
- Higher cutting area
- Can cut underwater
- High cut quality
Laser cutting machine
CNC laser cutting machine operates quite like plasma machines, in a way they both use non-contact thermal-based fabrication process suitable for metal and non-metal materials. Laser cutting machines uses a high power laser beam instead of a Plasma torch to cut through materials. These high power laser beams are focused on the material using laser optics. The high intensity of the laser beam is achieved by compressing highly reactive gases into a pressurizing container.
The three common types of lasers used are CO2 laser, Yttrium-aluminium-garnet laser and fibre laser. CO2 and YAG laser both have a similar construction but have a different application.
Application of different lasers
CO2 laser comes in two power levels i.e high power level and low power level. Low power level CO2 laser is used for engraving operation while the high power level is used for welding and cutting due to their reasonably lower costs.
YAG lasers have a higher peak output and can produce good results for the operation of metal marking and etching.
Fibre lasers have a solid-state construction and give a high-power output which helps to reduce the consumable costs and is effective for cutting a wide variety of materials.
Advantages of Laser cutting machine
- Faster processing and production times
- Less warping
- Higher accuracy compared to plasma cutting
- Less waste
- Ability to cut a wide variety of materials
Electric discharge machine
Electric discharge machine is also called a spark machine or spark eroding machine, as it uses rapidly recurring current discharges between two electrodes, known as a spark to remove material from the workpiece by melting or vaporizing it to gain the desired shape.
In electric discharge machining, the workpiece is placed between two electrodes with a very small electric field also known as spark gap. This assembly is submerged into a dielectric fluid which acts as a coolant and semiconductor between the electrode and the workpiece to maintain stable and controlled conditions to ignite a spark between the electrode and workpiece.
Types of Electric Discharge machines
Wire EDM is also known as spark EDM, wire erosion or wire burning EDM. Wire EDM uses a thin wire to cut the workpiece. In Wire EDM, the wire functions of an electrode which is made of either brass or copper. While machining operation the wire is automatically fed by a spool. This wire can easily be manipulated depending on where the cut needs to be made.
Sinker EDM is also known as cavity type EDM, volume EDM, RAM EDM or die-sinking EDM. Sinker EDM is used to produce parts with complex shapes. In sinker EDM the electrodes made from graphite and copper are used, which are pre-machined as per the required shape. The pre-determined electrodes are then sunk into the workpiece, producing a replica version of its original shape.
Hole drilling EDM
Hole drilling EDM as the name suggests is used for drilling holes in the workpiece. Hole drilling EDM compared to other traditional drilling machines are able to drill extremely small and deep holes. The electrodes used in hole drilling are tubular in shape and the dielectric fluid is fed by the electrode itself while machining.
Advantages of Electric Discharge machine
- Can machine complex shapes
- Good surface finish
- Extremely hard materials can be machined
- Can produce tapered holes
CNC routers machine is usually used to gain large dimensions in wood, metal, sheets and plastics. CNC router completely controlled by computer programs and the user does not need to manipulate the router by hand.
CNC routers are vastly used in industries to produce high-quality products consistently and improve industrial productivity.
Advantages of CNC Router
- Highly automated
- Reduction of waste and errors
- Less time consumption
Pick and Place machine
Pick and place CNC machines are sophisticated machines which consist of several nozzles that are used to pick up electrical components mainly for PCB assembly. As the name suggests these machines pick a component using vacuum create inside the nozzle and places it as per the required coordinates on the PCB assembly.
Pick and place machines are mainly used in the manufacturing of electrical circuit boards as small parts need to be assembled with extreme precision. Accurate positioning is of great importance because some components are very small, and also very sensitive to force. Pick and place machines enable to assemble these parts with extreme precision eliminating any human involvement.
Advantages of Pick and Place machine
- Can assemble small and delicate parts
- Eliminates human error
- Increases productivity
- Highly efficient
3D printing machine
3D printing machine is a part of a process known as additive manufacturing, where an object is created by adding material layer by layer. Additive manufacturing allows designers to create complex parts for machines, aeroplanes and cars at a fraction of the cost and time of standard means like forging, moulding and sculpting.
The most common material used for 3D-printing is plastic. But the use of some other materials allow for the creation of some pretty amazing products beyond simple tools and toys.
In the medical world, doctors are testing bio-materials for regenerative medicine. By using a patient’s cells, doctors could 3D print small body parts like ears and noses. Some surgeons have even tested 3D printed organs for transplants.
Advantages of 3D printing machine
- Faster production
- Easily accessible
- Better quality
- Tangible design and product testing
- Creative design and customization freedom
Application of different types of CNC machines across various industries
The medical industry depends hugely on customized products to meet the extremely rigorous medical standards to treat the patients. However, the medical sector relies on disposable items to maintain the health and hygiene standards of its facilities. This sector demands products with precision and high volume to fulfil the needs of patients. At the same time, it must fulfil the strict medical standards laid down by the medical regulatory bodies.
As the medical sector is continuously evolving with research carried on day and night to improve the quality and precision of treatment, it requires prototypes to be able to test the idea before implementing it into patients.
Various types of CNC machines like 3D printers adapt well to the needs of medical filed. Due to this adaptability, a wide variety of prototypes can be manufactured and tested like:
- Orthotic devices
- Electronic enclosures for monitoring devices
- Research equipment
- Shielded enclosures
- MRI machines
- Electrical parts
- Customized packaging to maintain sterility
- Medical instruments
In CNC machining process, an engineer can see a 3D model of the product using CAM software before machining it. This allows the engineers to rectify any possible margin of error to avoid any misdiagnosis and malfunctioning of the part.
Aviation industry like the medical industry depends on parts manufactured with extreme precision to avoid any damage to the aircraft. Aircraft have to undergo extreme pressures, high speeds and fast air currents, even a small disfunction can catch on an air current, producing drag or can wear out the parts faster.
CNC machines due to their high precision machining and manufacturing capacity can provide high precision parts with tolerances up to as tight as 0.00004 inches. Engineers can manufacture highly durable parts with materials like titanium, nickel, alloys, plastic and more.
Parts made for aerospace and aviation industry include-
- Landing gear parts
- Electrical connectors
- Radiofrequency suppression materials
Transportation industry just like the aviation industry depends on parts like engine, suspension, gears and other components which should have high surface finishes, toughness and long durability. As CNC machining allows to easily manufacture prototypes of a part before going into mass production, engineers can test, analyze and modify the parts as per required performance standards.
While the aviation industry depends on parts built for high speeds, extreme currents and forces, the transportation industry depends on parts which can undergo huge loads, high wear and tear, huge torques and strains. The parts manufactured for the transportation industry must be highly durable to carry loads over long distances and for a longer amount of time.
Parts and components manufactured for transportation industry using CNC machines include:
- Shipping vessels
- Freight trains
- Passenger rail
- 18-wheel transport trucks
- Passenger vehicles
Oil and gas industry
Petrochemical industries have large machinery and refineries to extract oil from the earth and to refine it into required products. Parts manufactured for the oil and gas industry include rigs, valves and pistons which need to fit perfectly, otherwise, a cylinder might not get filled due to insufficient pressure, a valve might leak or piston might not create the required pressure.
Petrochemical industries is another industry which requires parts with high tolerances. Unlike other industries, the petrochemical industries are located in extremely isolated places, so getting a replacement for faulty parts is quite difficult. That is why it’s necessary that parts manufactured for this industry are highly durable and can also withstand high tidal currents and corrosion due to salty seawater.
CNC machines are used to produce parts for pipelines, refineries and rigs which include:
- Drill bits
Military and Defence industry
Defence industry similar to the petrochemical industry require parts that can undergo the harshest of the environments. Parts manufactured for the defence sector just like the medical sector must fulfil certain defence standards for them to be employable on the field.
The defence industry consists of many sectors within itself so parts made for this sector are similar to the aviation, transportation, electronics and the medical sector. The defence industry evolves continuously at a faster rate than other industries to meet the defence standards and changing conditions.
Parts manufactured for the defence sector include:
- Communications components
- Transportation components
- Plane parts
Electronics parts in itself are made out of hundreds of small intricate parts which are assembled with extreme precision. Parts used in the electronics industry can be extremely compact, as small as the size of a fingernail depending on its application.
CNC machines due to their precision machining can achieve these small sizes with extreme precision and intricacy. They allow them to manufacture parts not just with small sizes but also very complex shapes.
Another reason why different types of CNC machines are used in the electronics industry is their ability to assemble parts with extreme precision and speed. Many electronics products are an assembly of small electronics parts which are difficult for a human to assemble with such high accuracy and speed.
Parts and components made for the electronics industry include:
- Heat sinks
- Amplifier housings
- Radiofrequency interference shielding
- Electrical insulation
Marine industry stays afloat thanks to the high-quality parts manufactured by CNC machines. The marine industry has unusual requirements as compared to the other industries.
Marine industry requires parts that can function properly which come directly in contact with water or partially in contact with water. Marine parts need to withstand high water pressures, high currents and corrosion due to moisture. Electronics parts used in ships and huge vessels need highly compact water casing to avoid any contact with water.
Components used for marine industry need to be highly resistant to water and need to be durable for a long time as replacement of faulty parts might not take place until the ship comes to the port. CNC machines hugely benefit the marine industry with its ability to make custom parts.
Parts produced for the marine industry using CNC machines are:
- Insulating cases
- Engine components
- Electronic parts
- Prototype moulds
- Boat parts
CNC machines will continue to be a useful means of production for various industries. The ability of CNC machines to create parts using different materials as per desired standards is another factor which makes CNC machines such a critical part of the manufacturing industries.
From small electronics parts to extreme complex parts like engines, CNC machines can manufacture highly customized parts according to the needs of the industry. To serve the needs of different industries and their various product requirements different types of CNC machines serve different purposes.
The ability to rapidly manufacture prototypes and test them before it goes into batch production is the major reason why CNC machines are so widely used across various industries for research and high output. Thus, different types of CNC machines will continue to serve different industries with new means of manufacturing and techniques developing in the future.