Section 13. qxd

Milling machines
use cutters with multiple teeth in
contrast with the single-point tools of the lathe and planer.
Milling-machine classification is based on design, operation, or pur-
pose. 
Knee-and-column
type milling machines have the table and saddle
supported on the vertically adjustable knee gibbed to the face of the col-
umn. The table is fed longitudinally on the saddle, and the latter trans-
versely on the knee to give three feeding motions.
Knee-type machines are made with horizontal or vertical spindles.
The 
horizontal
universal machines have a swiveling table for cutting
helices. The plain machines are used for jobbing or production work,
the universal for toolroom work. 
Vertical
milling machines with fixed or
sliding heads are otherwise similar to the horizontal type. They are used
for face or end milling and are frequently provided with a rotary table
for making cylindrical surfaces.
The 
fixed-bed
machines have a spindle mounted in a head dovetailed to
and sliding on the face of the column. The table rests directly on the bed.
They are simple and rigidly built and are used primarily for high-production
work. These machines are usually provided with work-holding fixtures
and may be constructed as plain or multiple-spindle machines, simple
or duplex.
Planer-type
millers are used only on the heaviest work. They are used
to machine a number of surfaces on a particular part or group of parts
arranged in series in fixtures on the table.
Milling Cutters
Milling cutters
are made in a wide variety of shapes and sizes. The
nomenclature of tooth parts and angles is standardized as in Fig.
13.4.16. Milling cutters may be classified in various ways, such as pur-
pose or use of the cutters (Woodruff keyseat cutters, T-slot cutters, gear
cutters, etc.); construction characteristics (solid cutters, carbide-tipped
cutters, etc.); method of mounting (arbor type, shank type, etc.); and
relief of teeth. The latter has two categories: profile cutters which pro-
duce flat, curved, or irregular surfaces, with the cutter teeth sharpened
on the land; and formed cutters which are sharpened on the face to
retain true cross-sectional form of the cutter.
Fig. 13.4.15
Basic types of milling cutters and operations. (
a
) Peripheral milling; (
b
) face milling; (
c
) end milling.
Two kinds of milling are generally considered to represent all forms
of milling processes: