Yangon Technological University
Department of Mechanical Engineering
Workshop Technology II
WS-22012
Daw Ei Ei Soe
Lecturer
09757866071
eieisoe.me@gmail.com
Chapter (14)
Milling Machine Processes
1. What is meant by
milling as it applies to
machining?
➢ Milling is a process of
removing material with
a rotating multipletooth cutting tool called
a milling cutter.
➢ In the usual operation,
the workpiece is fed
against the rotating
cutter.
Figure.1 Milling Process
2
2. What kinds of jobs can be done on a milling machine?
The milling machine is used to machine
❖ flat and angular surfaces
❖ drill and bore holes
❖ slot keyways
❖ cut gear teeth
❖ mill screw threads
❖ cut irregular shapes
❖ cut helical flutes in twist drills and milling cutters, and
❖ do speciality work for which it can be adapted.
3
3. How many types of milling machines are used
and how are they classified?
There are three types of milling machines:
(a) knee- and-column milling machines,
(b) manufacturing milling machines, and
(c) special milling machines.
5
4. What type of milling machine is most often found in
small, general machine shops?
➢ The knee-and- column type.
➢ It is a general purpose machine with a full range of
speeds and feeds, which are controlled either manually or
automatically.
➢ There are three styles of knee and column milling
machines: (a) plain, (b) universal, and (c) vertical.
5. What is the function of the column?
➢ The column, including the base, is the main casting,
which supports all the other parts of the machine.
➢ The front of the column, the column face, is machine to
provide an accurate guide for the vertical travel of the
knee.
6
6. What is the function of the knee?
➢ The knee supports the saddle.
➢ The feed-change gearing is enclosed within the knee.
➢ The knee can be raised or lowered on the column face.
➢ It is supported and can be adjusted by the elevating
screw.
7. What is the function of the saddle?
➢ The saddle supports the table.
➢ It is supported and guided by the accurately machined
surface of the knee.
7
8. What is the purpose of the table?
➢ The table holds the workpiece.
➢ It rests on the dovetailed guides of the saddle.
➢ T slots are machined along the length of the top surface
of the table.
➢ They are used to align the job or the fixture, which holds
the job.
➢ Bolts fit loosely in the T slots and are used to clamp the
job, vise, or fixture to the table.
9. What is the purpose of the spindle?
➢ The spindle holds and drives the various cutting tools.
➢ It is a shaft mounted on bearings supported by the
column.
➢ The spindle is driven by an electric motor through a train
of gears all mounted within the column.
➢ The front end of the spindle has a tapered hole and
driving keys for location and driving various cutting tools,
chucks, and arbors.
10.What is the overarm?
➢
The overarm is mounted on the top of the column and
is guided in perfect alignment by the machined
dovetailed surfaces.
➢
It supports the arbor and is adjustable and can be
tightened in any position. Some machines have two
round over arms.
11. What is a vertical knee-and-column milling machine?
➢ The vertical milling machine is so named because the
spindle is located vertically and at a right angle to the
surface of the table.
➢ The spindle has a vertical movement and the table can be
moved vertically, longitudinally and transversely.
➢ Both the spindle and table movement can be controlled
manually or by power.
➢ The vertical-spindle milling machine can be used for face
milling ,milling dies and locating and boring holes.
➢ When used in conjunction with precision measuring
instruments this machine can be utilized as a very
efficient jig borer.
12
12. What is a precision jig-boring machine?
➢ A precision jig borer is a machine specially designed to
simplify boring holes to accurate size and to simplify
the problems of precisely locating the holes, in many
ways, it resembles a vertical milling machine in the
earliest stages of development, the machine looked
like a single spindle drill press.
➢ The jig borer’s rigid construction prevents vibration
and sag.
➢ The ways are made of steel and are hardened, ground,
and lapped.
➢ The table can be set in either direction to an accuracy
higher than 0.0001 in. Holes can be located to a
tolerance of 0.00005 in.
13
14
13. What is a tool and die milling machine?
➢ A tool and die milling machine is designed for the milling of curved
or irregular surfaces and surfaces located between projections
shoulders, and bosses.
➢ By means of a tracer riding on a cam the cutter automatically
reproduces intricate shapes accurately.
➢ This machine also performs the usual milling machine operations.
14. What is a milling machine attachment?
➢ Every machine used in machine shop work has one or more
attachments.
➢ An attachment is designed to give the machine greater versatility, or
work capability.
➢ The milling machine has many attachments, which add to its
adaptability, efficiency, and convenience.
15. What is a vertical milling attachment?
➢ The vertical milling attachment can be mounted on the face
of the column of a knee and column milling machine.
➢ Plain and universal milling machines can then perform the
operations ordinarily done on a vertical milling machine.
➢ The spindle head can be swiveled accurately to any degree
for angular milling.
16. What is the universal milling attachment?
➢ A universal milling attachment makes a milling machine
truly universal because its spindle may be set at any angle
in both planes.
➢ This allows an end mill to do the work of an angular cutter.
17. What is a slotting attachment?
➢ When mounted on the column face of a plain or
universal milling machine the slotting attachment
converts the rotary motion of the spindle into the up
and down motion of the tool slide.
➢ This is particularly valuable in a shop where keyways
must be machined and no slotting machine is available.
➢ The tool slide of this attachment can be set at any
between 0 and 90° on either side of the center line.
➢ The stroke can be set from 0 to 4 in .
18
18. What is a rack milling attachment?
➢ A rack milling attachment is used to cut teeth usually
gear teeth along a straight line.
➢ It can also be used in connection with the universal spiral
index centers for cutting worms on universal milling
machine.
➢ The cutter is mounted on the end of a spindle that
extends through the attachment case parallel to the table
T slots.
➢ This spindle is driven from the machine spindle by a
train of hardened steel bevel and spur gears.
➢ A vise which simplifies the holding of the rack, is
furnished as a part of the attachment.
20
19. What is a milling fixture?
➢ A milling fixture is a work-holding device that is
clamped to the table for machining duplicate parts on a
production basic.
➢ Once the fixture is accurately aligned and set to the
cutter, or cutters, and the first piece is machined and
checked for a accuracy, all of the following workpiece
need only be clamped in the fixture and machined.
➢ When the table-feed is being used to feed the
workpiece against the cutter, the vertical-feed and the
cross-feed clamps must be tightened to provide a rigid
setup and maintain the accuracy.
20. What are plain milling cutters?
➢ Plain milling cutters are made with cutting edges on
the periphery of the cutter only.
➢ They are used for cutting keyways and slots and for flat
surfaces that are narrower than the width of the cutter.
➢ Plain milling cutters that are more than ¾ in .in width
are usually made with spiral teeth.
➢ The helical plain cutter is specially desirable when an
uneven surface, or one with holes in it, is to be milled.
21. What are side milling cutters?
➢ Side milling cutters are cutters with teeth on both
sides as well as on the periphery.
➢ They are used for cutting slots that must be accurate
in width.
➢ They are also used for straddle milling, in with case
two cutters are mounted on an arbor with spacers
between them, as when milling two sides of a
casting or two sides of the head of a bolt.
➢ The staggered-tooth side milling cutter is used when
deep cuts are required.
➢ With this type of cutter, it is possible to operate at a
higher speed and feed than with an ordinary cutter.
23
24
22. What are slitting saws?
➢ Slitting saws are very thin cutters varying in thickness
from 1/32 to 3/16 in..
➢ They are used to cut deep. Slots and to cut material into
required lengths.
➢ The cutter is thinner at the center than at the edge, to
provide clearance and to prevent the cutter from binding
in the slot.
➢ Another style of cutter is preferred when deep slots must
be cut at high speed.
➢ They are also used for cutting slots in the heads of
screws.
26
23. What are angular cutters?
➢ Angular cutters may be single, or double.
➢ They are used to cut teeth in flat and rotary cutters and to
cut the flutes of drills and reamers.
Double Angle Cutter
Single Angle Cutter
24. What are form cutters?
➢ Form cutters are designed to cut definite shapes.
➢ Examples of these are the convex cutter, the concave
cutter, and corner-rounding cutters.
Convex cutter
Concave cutter
Corner-rounding
cutter
28
25. What is a T-slot cutter?
➢ A T-slot cutter is used to cut T-shaped slots similar to those
in the milling machine table.
➢ It is available in many sizes.
29
30