Milling machines facilitate in removing metal pieces through a rotating cutter. The rotation of the cutter takes place at high speed, which helps it cut through metal efficiently. Furthermore, these cutters have cutting edges that play a vital role in cutting materials. These types of presses perform on various types of milling machines.
Milling machines can hold more than one cutter at a time. It is the most important machine that you can find in a workshop. You can perform operations with high accuracy. It has a high rate of metal removal compared to other similar machines, such as a shaper, planner, and lathe machines.
These machines are famous for their better surface finishing and excellent accuracy, making them a necessity for production work.
Types of Milling Machines
Some of the main types of milling machines are as under:
1. Horizontal or Plain Milling Machine
Plain milling machines are more robust than hand millers. The plain milling machines that have a horizontal spindle are also called horizontal milling machines. You can feed the table in vertical, cross, or horizontal directions.
In other words, horizontal milling machines mount the cutting tool on a horizontally oriented spindle that’s able to selectively remove material from the stationary workpiece. Furthermore, horizontal milling machines usually feature different cutting tools than vertical milling machines.
Horizontal milling machines feature a similar design in which a spindle containing a rotating cutting tool presses against a workpiece to remove material from the workpiece. With that said, horizontal milling machines differ from their vertical counterparts in several ways.
The biggest difference between these two types of milling machines is the orientation of the spindle. With vertical milling machines, the spindle features a vertical orientation. With horizontal milling machines, the spindle features a horizontal orientation.
The feed includes:
- Verticle – adjusts the table vertically.
- Cross – moves the table parallel to the spindle.
- Longitudinal – rotates the table
2. Vertical Milling Machine
The position of the spindle on a vertical milling machine is perpendicular or vertical to the table. You can use this machine for slots, machining grooves, and flat surfaces. The spindle head is fixed to a vertical column, which rotates at an angle. The milling cutter is fixed on the spindle to work with angular surfaces. In some vertical milling machines, you can adjust the spindle up and down.
A vertical milling machine is a precision tool used for shaping and fabrication by the removal of stock typically from metallic workpieces. Plastics and other materials can also be machined on the mill depending upon tooling and material.
Mill controls may be manually operated, computer numerical controlled (CNC), or a combination of both. Mill machining and material removal are typically made by a rotary cutter held in a spindle.
Cutting options are more sophisticated and variable than a drill press by virtue of a moveable table and/or vise (x and y-axes) and vertical spindle movement (z-axis). Many vertical mills also have a rotatable turret for the upper cutting head which provides even greater machining options (b-axis).
A diagram is included in this procedure to help illustrate the varying axes. Some of the common operations that can be performed on these types of milling machines:
- Milling: These operations provide a flat surface or spot on a workpiece, typically with a specific orientation to other workpiece features, surfaces, or another piece. Facing is sometimes used on an irregularly shaped workpiece to “true” one surface at a time to ensure that all surfaces have appropriate specific geometric relationships with each other.
- Slotting or keyways Slots, flats, or keyways can be cut with proper fixturing.
- Drilling or boring Where specific orientations are required between workpiece features, the vertical mill provides the means to accurately index and machine holes.
3. Universal Milling Machine
Universal Milling Machine is a milling machine having a table fitted with all motions and a dividing head with change gears so that it can perform any type of milling operation.
It can adapt to perform a wide range of operations. The table can pivot at any angle for up to 45-degrees on both sides from the normal position. As the table of the horizontal milling machine can move in three directions, it also boasts the fourth movement.
This machine can also perform helical milling operations. You can also use additional attachments to increase the capacity of the machine.
Some special attachments include:
- Slotting attachment
- Rotary attachment
- Vertical milling attachment
- Index head or dividing head
You can produce a milling cutter, reamer, twist drill, spiral, bevel, spur, and much more from this machine. You can perform all the operations that a shaper machine does with the universal milling machine.
4. Simplex Milling Machine
The spindle or the spindle head can travel in one direction only. The most common direction in which it can move is vertical.
These types of milling machines have:
- Stable Milling
- Excellent Surface Finish and Flatness of Milled Surfaces.
- High tool life, high productivity & low maintenance.
5. Duplex Milling Machine
Duplex milling machines are two machines located opposite the other, which can work separately or as a single milling machine when the workpiece can be machined with 2 simultaneous spindles. The spindle can move in both horizontal and vertical directions.
Main advantages of the duplex solution:
- Production increase of up to 50% in relation to conventional solutions, i.e. individual milling machines
- Improvements in part precision, by managing to do the machining of the part in one single setup, in most of the cases
- One sole operator can control the duplex milling machines
- Reduced space and investment requirement comparing with two single machines
- Fast investment amortization due to the high productivity
- Duplex solution admits different configurations: single working area, pendulum working areas, or pallet changing system
6. Triplex Milling Machine
The spindle can move in all three directions i.e. X Y and Z axis.
- Special application based on the customer’s requirements of related accuracies.
- Highly productive and accurate.
7. Rotary Table Milling Machine
Rotary Milling is the ability to perform 2D and 2.5D machining cycles around or on the end of a cylinder. When performing radial machining (around the cylinder), the tool is restricted to moving parallel to and around the rotary axis. The tool is always oriented radially to the centreline of the rotary axis.
The rotary table milling machine consists of a circular table that rotates on a vertical axis. You need to set multiple cutters at different heights. The machine works with one cutter roughing up the workpiece, and the rest of the cutters finishing the surface.
The operator can load and unload the workpieces continuously while the machine is working, and that is the most significant advantage of the rotary table milling machine.
8. Tracer Controlled Milling Machine
Tracer-controlled milling machines are equipped with copying capabilities through tracer control, and hence car reproduces or duplicates external or internal geometries in two dimensions. Tracer-controlled milling machines are used for machining cams, grooves, contoured surfaces, etc.
This machine is perfect for tracing the elements and reproducing dies with complex and irregular shapes. The stylus energizes the oil relay system, operating the primary hydraulic system of the table. This type of arrangement is called servomechanism and is complicated.
Tracer-controlled milling machines are used for machining cams, grooves, contoured surfaces, etc. Die sinking and other processes involving the machining of cavities can be done on three-dimension profilers or duplicators.
9. CNC Milling Machine
CNC milling, or computer numerical control milling, is a machining process that employs computerized controls and rotating multipoint cutting tools to progressively remove material from the workpiece and produce a custom-designed part or product.
A CNC Milling Machine uses a rotating cylindrical cutter to move along multiple axes, and create slots, holes, and details in material to turn it into a vehicle or mechanical part. Most machines operate on three to five axes, creating much more precision and detail.
Modern CNC milling machines are assembled as both horizontal and vertical machining centers. Components can be made with materials such as plastics, ceramics, and composite materials, in addition to metals.
Technical features include automatic tool changers, tool carousels & magazines, coolant systems, and enclosures to keep machines running smoothly on their own without manual interference.
10. Drum Milling Machine
Drum milling machines are used for production work only. This type of machine has a vertical central drum that rotates on a horizontal axis much like a Ferry’s wheel.
The cutters are of face mill type and usually both roughening and finishing cutters similar to those of a rotary-table miller are employed.
In operation, the drum- fixture rotates slowly, carrying the work against the rotating cutters. Usually, there are four cutter spindles. The operation is continuous since machined parts are removed and new ones added after the work has completed its cycle.
Automobile cylinder heads and small shafts are milled on this machine. These are the types of milling machines in general uses in industrial operation.
11. Turret Milling Machines
A turret machine is a versatile milling machine that can be used in the creation of many parts. Also, known as a Bridgeport-type milling machine, these machines can be repositioned opening a broader range of uses.
12. C-Frame Milling Machines
C-frame milling machines are sturdy and powerful. They use a hydraulic motor and are best utilized in industrial settings.
13. Tracer Controlled Milling Machines
Designed to produce duplicate parts based on a master model, tracer-controlled milling machines can be used for machining grooves and contoured surfaces.
14. Bed Type Milling Machines
The worktable of a bed type milling machine is placed on the bed itself, as opposed to on top as with other milling machines. On a bed type machine, the knee is omitted to allow for longitudinal movement.
15. Column Milling Machines
Often used for creating car parts, a column milling machine is one of the simplest types of milling machine. They consist of 5 key parts the worktable, head, saddle, knee, and over the arm, and use a vertically suspended drill.