CNC machines are classified
according to the nature of the work they perform. Popular CNC machines include
CNC Machining centers, CNC Turning Centers, CNC Grinding machines, CNC Laser
cutting machines, CNC Plasma cutting machines, CNC Routers, and 3D Printers,
all of which have various applications. However, the most commonly used metal
cutting machines in different modern industries are the CNC machining center
and CNC turning center. CNC machining centers are typically categorized as
vertical or horizontal machining centers, depending on the direction of the
spindle movement. In vertical machining centers, the spindle movement is
perpendicular to the base, while in horizontal machining centers, it is
parallel. Most CNC machining centers are equipped with automatic tool change
and workpiece changing systems. Sometimes, a single CNC machine is capable of
performing two different machining operations, such as milling and turning, and
is referred to as a turn-mill center. CNC machines are also classified based on
the number of controlled axes they have, such as two, three, four, and five-axis
CNC machines. The selection of a CNC controller usually depends on the number
of axes to be controlled. A basic CNC controller is suitable for managing two
to three axes, while an advanced CNC controller is capable of handling
simultaneous movements of five or more axes. The basic working principle of all
types of CNC machines is roughly the same. The following pictures depict
various types of CNC machines.
CNC Machining center
A CNC machining
center (also known as CNC milling center or CNC milling machine) is a
computer-controlled machine tool used for machining various materials,
primarily metal, but also plastics and wood. The term "CNC" stands
for Computer Numerical Control, which means that the machine's movements and
operations are controlled by a computer program and precise numerical commands.
CNC machining centers are capable of performing a wide range of cutting
operations, such as milling, drilling, tapping, reaming, and other precision
machining processes. These machines are widely used in manufacturing industries
for producing complex and precise parts with high accuracy and repeatability.
The CNC machining center is
the most popular machine tool used for milling operations. In milling machines,
the cutting tool is clamped with the machine spindle and rotates at high speed.
It removes excess material from the workpiece, which is mounted on the machine
bed and moves in different directions. Horizontal and vertical milling machines
are two types of CNC machining centers widely used in the machining industry.
The spindle movement is perpendicular to a vertical milling machine and
horizontal to the other. Most CNC machining centers offer 3 to 5 axes and can
have a single or multi-spindle for complex milling operations. Some CNC
machining centers are equipped with automatic tool changing and automatic
pallet changing facilities to improve efficiency.
CNC Turning center
Another popular machine used
in the machining industry is the CNC turning center, where the workpiece is
clamped with the machine spindle and rotates at high speed. With the controlled
movement of a stationary cutting tool, the material is removed from the workpiece.
Turning is a machining process used to manufacture cylindrical parts. A turret
with different cutting tools is affixed to the machine and programmed to remove
material from the workpiece to achieve the desired dimensions. Two types of CNC
turning centers are commonly used in the machining industry: slant bed type and
flatbed type. Among them, the slant bed type turning center is widely employed
and may have additional facilities.
CNC
turning centers are widely used in various industries, including automotive,
aerospace, medical, and general manufacturing. They are capable of producing
precise and intricate components with excellent surface finish and dimensional
accuracy. CNC turning is particularly well-suited for high-volume production of
cylindrical parts, making it an essential tool in modern manufacturing
processes.
CNC Turn-mill center
A turn-mill center is
capable of performing both turning and milling operations on the same machine.
It is a turning machine where milling operations are also performed on a
cylindrical workpiece. The turret of the machine contains multiple fixed
cutting tools for turning processes, and live tools (which can rotate) are
added for milling operations. The machine is programmed to remove material from
the cylindrical workpiece. Sometimes, mill-turn machines are also found, where
milling is the primary operation and turning is a supplementary machining process.
CNC turnmill
centers typically have a main spindle that is used for turning operations, and
a sub-spindle that is used for milling operations. The main spindle is usually
located in the center of the machine, while the sub-spindle is located on the
side of the machine. CNC turnmill centers can be configured with a variety of
tools, including turning tools, milling tools, and drilling tools. This allows
them to be used to manufacture a wide range of parts, from simple to complex.
CNC
turnmill centers are a valuable tool for manufacturers who need to produce
high-quality parts with high accuracy and repeatability. They are also a good
choice for manufacturers who need to produce complex parts that would be
difficult or impossible to manufacture on traditional lathes or milling
machines.
CNC Grinding Machine
Grinding is a machining
process that uses a rotating abrasive wheel as a cutting tool. Each grain on
the wheel's surface cuts or removes a tiny chip from the workpiece. Grinding
machines are commonly used for hard and fine machining, removing a small amount
of material. Sometimes, a center-less cylindrical grinder is used for grinding
with rotated workpieces.
CNC
grinding machines are commonly used in various industries, including
automotive, aerospace, tool and die making, medical, and precision engineering.
They are employed for grinding tasks such as cylindrical grinding, surface
grinding, centerless grinding, internal grinding, and form grinding. These
machines are known for their ability to produce extremely accurate and
high-quality finished parts with tight tolerances and excellent surface
finishes.
CNC Laser cutting machine
Laser cutting
is a thermal process where a focused laser beam is used to melt the material,
forming the expected dimensions. In this process, a laser beam is applied to
vaporize or melt and remove the material slowly from the workpiece. CNC laser
cutting typically uses optics, supporting gas, and a control system to
precisely direct and focus the laser beam into the workpiece. A continuous cut
is generated by passing the laser beam or sometimes moving the workpiece under
CNC control. This process is suitable for cutting a wide range of materials
such as metal, plastic, wood, glass, and paper.
The
process of laser cutting involves focusing a concentrated beam of light,
typically from a CO2 or fiber laser, onto the surface of the workpiece. The
intense heat of the laser beam melts, burns, or vaporizes the material,
creating a narrow cut known as the kerf. The CNC laser cutting machine's computer
controls the positioning and movement of the laser beam, allowing it to follow
the desired cutting path precisely. CNC laser
cutting machines are widely used in various industries, including
manufacturing, aerospace, automotive, electronics, and signage. They offer
several advantages, such as high cutting precision, fast cutting speeds,
minimal material wastage, and the ability to cut intricate and complex shapes.
Laser cutting is particularly suitable for cutting thin to medium-thickness
materials, making it an essential tool in modern metal fabrication and sheet
metal processing.
CNC Plasma cutting machine
Plasma cutting
is a process where an accelerated jet of hot plasma is forced at high speed
through a nozzle to cut a workpiece. In this process, an electric arc is
injected into the gas to ionize and form a plasma, which is then used to
machine the metal. An electrical current passing through the ionized air
between an electrode and the workpiece generates tremendous heat, melting the
metal and blowing it away. CNC plasma cutting refers to the cutting of metals
using a plasma torch, precisely controlled by a CNC controller.
The
process of plasma cutting involves creating an electrical circuit between the
plasma cutting torch and the workpiece. When the torch comes into contact with
the material, an electric arc is formed, ionizing the gas (typically air,
nitrogen, or oxygen) and creating plasma. The plasma reaches extremely high
temperatures, melting through the material, while the high-velocity gas blows
away the molten metal, resulting in a clean cut. Plasma cutting is
especially suitable for cutting thick metals and producing parts with smooth
edges. It is a cost-effective method for high-speed cutting of metal sheets and
plates, making it a popular choice for industrial cutting applications.
CNC Router
A manual
router is a hand-held electric power tool commonly used to rout or cut
different materials such as wood and plastic into different shapes. It has a
high-speed rotating cutter and removes the wood or plastic in its path when an
operator pushes it forward. A CNC router functions similarly to a hand-held
router but is operated through a CNC milling operation, accurately controlled
by a controller. CNC wood routers are widely employed to create complex wood
crafts by precisely controlling the movement of axes.
CNC routers are
designed to handle a wide range of materials and thicknesses, and they can
produce intricate designs with excellent detail. They are often used for tasks
such as 2D and 3D carving, contouring, pocketing, drilling, and engraving. CNC
routers come in various sizes, from small desktop models suitable for hobbyists
and small workshops to large industrial machines used for heavy-duty
production. The choice of CNC router depends on the specific application, the
size of the workpieces, and the level of precision and complexity required.
EDM wire-cutting machine
Electrical
Discharge Machining (EDM) is a process of machining where a 'tool' discharges
thousands of sparks onto a metal workpiece. With an EDM wire-cutting machine,
electrical discharge between a 'wire' and the workpiece creates sparks that
rapidly cut away material. Non-ferrous wires, such as steel, titanium, and
brass, are commonly used in EDM machining. The material melts or evaporates
instead of being cut, leaving behind minute debris and providing very accurate
dimensions. As the charged wire never contacts the workpiece, there are no
cutting forces involved, making it possible to manufacture tiny and precise
parts with EDM wire-cutting machines.
CNC EDM wire
cutting machines are widely used in various industries, such as aerospace,
automotive, tool and die making, and precision engineering. The wire EDM
process provides high precision, excellent surface finish, and the ability to
work with hard materials or delicate components without causing mechanical
stresses. CNC EDM wire cutting machines are essential tools in modern
manufacturing for producing molds, dies, tooling, and various intricate parts
that require extreme accuracy and intricate details.
3D Printing machine
3D printing,
or additive manufacturing, is a process of creating three-dimensional solid
objects by depositing materials layer by layer, following a 3D digital model or
programming. A 3D-printed object is constructed using additive manufacturing,
which involves laying down successive thin slices of material until the object
is complete. It can be considered the opposite of subtractive manufacturing
processes like milling and turning.
There
are several types of 3D printing technologies, each with its own unique
approach to creating three-dimensional objects. Some common types of 3D
printings are :
- · Fused Deposition Modelling or FDM - Here the printers use a heated nozzle to extrude and deposit thermoplastic filament layer by layer to build the object.
- · Stereolithography or SLA – Here the printers use a liquid photopolymer resin that is cured layer by layer using an ultraviolet (UV) laser or a light source.
- · Selective Laser Sintering or SLS – Here the printers use a high-powered laser to selectively fuse powdered materials (typically plastic, metal, or ceramic) layer by layer, creating durable and functional objects.
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