milling machine

                                 milling machine

Milling is an operation in which metal is removed from a workpiece by a rotating milling cutter. The workpiece can be moved in three directions at

right angles to each other, with respect to the cutter. The three directions

are longitudinal, transverse, and vertical, respectively. There are two basic

types of milling machines. In one the axis of the cutter is perpendicular to

the surface of the workpiece and this is called a vertical

milling machine. 

In the other, the axis of the milling cutter is parallel to

the surface of the workpiece and this is called a horizontal milling

machine 

Both types are used extensively in the manufacture of various parts of

the mould.

The table assembly is identical for both machines and we will, therefore,

discuss this feature first. The table is mounted on the slideways of the

saddle, which allows the table to be moved longitudinally. The saddle is

mounted on slideways of the knee and these slideways are at right angles

to the saddle slideways, which permits the workpiece to be traversed.

Finally, the knee, which is the main supporting member, is mounted on

the vertical slideways of the column. This allows for the workpiece to be

adjusted vertically. In the horizontal machine, the depth of cut is preset by

this vertical movement. However, with the vertical machine, the vertical

movement of the knee is used primarily to bring the workpiece close to

the milling cutter, the actual depth of cut being preset by vertical

movement of the spindle on which the cutter is mounted.

The vertical milling machine incorporates a vertical

milling head mounted on a horizontal extension of the column. The head

comprises a spindle suitably driven by an electric motor via a belt

transmission system. The spindle, which is rotated at high speed, can be

fed in the vertical direction either manually, or automatically via the drive

system. an endmill cutter is fitted into the spindle.

 This

type of cutter incorporates cutting edges both on its periphery and on its underside. Thus the cutter can be sunk into the workpiece which can then a moved either longitudinally or transversely depending upon the form required.