Types of Milling Machine

  

Type of Milling Machines

Milling machines can be classified into different categories depending upon their construction, specification and operations. The choice of any particular machine is primarily determined by nature of the work to be done, its size, geometry and operations to be performed. The typical classification of milling machines on the basis of its construction is given below.

The broader classification has three categories and each category has its sub-classifications given below :

1-   Column and Knee Type Milling Machine

(a)            Head milling machine

(b)            Plain milling machine

(c)     Universal milling machine

(d)     Omniversal milling machine

(e)     Vertical milling machine

2-   Fixed Bed Type Milling Machine

(a)     Simplex milling

(b)     Duplex milling

(c)     Triplex milling

3-  Special Type Milling Machine

        (a)     Rotary table milling

(b)     Drum milling

(c)     Planetary milling

(d)     Tracer controlled milling

In addition to above three types there is one more type of milling machine named as planner type milling machine which is rarely used.

1-    Column and Knee Type Milling Machine

                                                                      Main shape of column knee type of milling machine is shown in Figure 1.3. This milling machine consists of a base having different control mechanisms housed there in. The base consists of a vertical column at one of its end. There is one more base above the main base and attached to the column that serves as worktable equipped with different attachments to hold the workpiece. This base having worktable is identified as “knee” of the milling machine. At the top of the column and knee type milling machines are classified according to the various methods of supplying power to the table, different movements of the table and different axis of rotation of the main spindle. These are described in brief as below.

(a)   Head Milling Machine

                                               In case of head milling machine feed motion is given by hand and movements of the machine are provided by motor. This is simple and light duty milling machine meant for basic operations.

(b)  Plain Milling Machine

                                            Plain milling machine is similar to hand milling machine but feed movement can be powered controlled in addition to manual control.

(c)   Universal Milling Machine

                    

                                           A universal milling machine is named so as it is used to do a large variety of operations. The distinguishing feature of this milling machine is it table which is mounted on a circular swiveling base which has degreegraduations. The table can be swiveled to any angle upto 45o on either sideof normal position. Helical milling operation is possible on universal milling machine as its table can be fed to cutter at an angle. Provision of large number of auxiliaries like dividing head, vertical milling attachments, rotary table, etc. make it suitable for wide variety of operations.

(d)Omniversal Milling Machine

Omniversal milling machine is like a universal milling machine with additional feature that its table can be tilted in a vertical plane by providing a swivel arrangement at the knee. This enables it to make taper spiral grooves in reamers, bevel gears, etc.

(e)Vertical Milling Machine

Position of spindle is kept vertical or perpendicular to the worktable in case of vertical milling machine.

2-     Fixed Bed Type Milling Machine

It is also known as manufacturing type milling machine. Its table is mounted directly on the ways of fixed bed. Table movement is restricted to reciprocation only. Cutter is mounted on the spindle head which can move vertically on the column. Duplex milling machine has double spindle heads, one on each side of the table. Triplex milling machine has three spindle heads one each side of the table and third one is mounted on the cross rail. Bed type milling machine is shown in

Planer Type Milling Machine

It is a heavy duty milling machine, its spindle head is adjustable in vertical and transverse directions. It is different from planner as feed is given to the worktable. This can accommodate a number of independent spindles carrying milling cutters on the rail. Independent driving of the different spindles is possible so multiple operations are possible simultaneously.

3-     Special Type Milling Machines

These are the special purpose milling machines, entirely different in design and construction from the conventional milling machines. In case of rotary table milling machine face milling cutters are mounted on two or more vertical spindles and a number of workpieces are clamped on the horizontal surface of a circular table which rotates about a vertical axis. Different milling cutters are mounted at different heights. Loading and unloading are possible while milling is in progress. In case of drum milling machine the worktable rotates about a horizontal axis and is called drum. In a planetary milling machine, the work is held stationary while the revolving cutters in a planetary path. It is used to finish cylindrical surface of a workpiece internally or externally or both. Pantograph milling machine reproduced the workpiece at any desired scale of pre-decided model. Profiling machine duplicates full size of the template attached to the machine. Tracer milling machine can produce any pre-decided irregular or complex shapes of dies, moulds by synchronizing movements of the cutter and tracing elements.