MILLING MACHINES

GENERAL TYPES

Hand milling machines may be of the column and knee type or constructed with a table mounted on a
fixed bed. This type of machine is intended for small work only. The hand feed operates by means of
levers or a hand screw for work such as slotting and cutting grooves and key ways.

The machine is provided with a horizontal spindle with speeds of 75 to 4,000 rpm (4- ranges). The
worktable has longitudinal and vertical feeds also a cross feed. A machine of this type can be used for
production work if provided with stops and specially designed fixtures where parts can be rapidly
loaded and unloaded.

Milling machines are designed to hold and rotate a milling cutter, hold a work piece, and feed the work
piece to the milling cutter in one of several directions. The work piece may be held directly, or indirectly,
on the table of the milling machine.

The table and the work piece may be moved or adjusted about the rotating milling cutter, in three
directions, that is vertical, horizontal, parallel to the rotational axis of the spindle, and horizontal,
perpendicular to the rotational axis of the spindle. Along any one of these three directions, feeding may
be accomplished.

Movements along the other two directions then are used for locating the cut that includes obtaining the
depth of cut. Adjusting the movements along these three directions can be controlled to within 0.00 1
inch.

Milling machines are available in several different types, and can be used for making a large variety of
machining cuts. Milling machines with a horizontal spindle for rotating the milling cutter are called
horizontal milling machines. Milling machines with a vertical spindle are called vertical milling machines
that we will be using here.

VERTICAL MILLING MACHINES

A vertical milling machine has the same table movements as a horizontal machine. It is called a vertical
milling machine because the spindle is located vertically and at right angles to the top of the table. The
head may be swiveled for angular or bevel milling operations.

Vertical milling machines use end-milling cutters of various types and sizes depending upon the kinds of
operations to be performed. These operations consist of milling horizontal surfaces, angular surfaces,
milling grooves, key ways, T-slots, and dovetails.

Vertical milling machines can also be used for drilling and boring operations where it is necessary to
space a number of holes accurately. In this type of operation, dial gages, veneer scales, precision