UNIVERSITY VOC COLLEGE OF ENGINEERING
(A Constituent College of Anna University , Chennai )
THOOTHUKUDI CAMPUS - 628008
ME8712 - TECHNICAL SEMINAR PRESENTATION
ABOUT MILLING MACHINE
NAME : PONSELVAN P
REGISTER NO. : 953220114304
YEAR : IV
BRANCH : MECHANICAL ENGINEERING
INTRODUCTION :
• Transmission electron microscopes (TEM) are microscopes that use a particle
beam of electrons to visualize specimens and generate a highly-magnified image.
TEMs can magnify objects up to 2 million times.
• In order to get a better idea of just how small that is, think of how small a cell is. It
is no wonder TEMs have become so valuable within the biological and medical
fields.
HOW DOES WORK :
• TEMs employ a high voltage electron beam in order to create an image. An
electron gun at the top of a TEM emits electrons that travel through the
microscope’s vacuum tube.
• Rather than having a glass lens focusing the light (as in the case of light
microscopes), the TEM employs an electromagnetic lens which focuses the
electrons into a very fine beam.
• This beam then passes through the specimen, which is very thin, and the electrons
either scatter or hit a fluorescent screen at the bottom of the microscope.
• An image of the specimen with its assorted parts shown in different shades
according to its density appears on the screen. This image can be then studied
directly within the TEM or photographed. Figure 1 shows a diagram of a TEM
and its basic parts.
What are the difference between a TEM and a Light Microscope:
• Although TEMs and light microscopes operate on the same basic
principles, there are several differences between the two.
• The main difference is that TEMs use electrons rather than light in
order to magnify images.
• The power of the light microscope is limited by the wavelength of
light and can magnify something up to 2,000 times. Electron
microscopes, on the other hand, can produce much more highly
magnified images because the beam of electrons has a smaller
wavelength which creates images of higher resolution. (Resolution is
the degree of sharpness of an image.) Figure 2 compares the
magnification of a light microscope to that of a TEM.
VERTICAL MILLING MACHINE :
• Here 3
UNIVERSAL MILLING MACHINE :
• It can be adapted to a wide range of milling
operations. Here the table can be swiveled to any
angle up to 45-degrees on either side of the normal
position.
• In addition to 3 movements as mentioned earlier in
a plain milling machine, the table may have the
fourth movement when it is fed at an angle to the
milling cutter. Helical milling operation can also be
performed. This machine can produce spur, bevel,
spiral, twist drill, reamer, milling cutter. All
operations that are Performed on a shaper can be
done using a universal milling machine.
OMNIVERSAL MILLING MACHINE :
• Here the table also has four movements of the universal
milling machine. It can also be tilted in a vertical plane by
providing a swivel arrangement at the knee.
• The additional swivelling arrangement of the table helps in
machining spiral grooves in reamers and bevel gears.
PLANER TYPE MILLING MACHINE :
• This types of milling machine are also called as
“Plano-Miller”. It is a massive machine used for
heavy-duty work having spindle heads
adjustable in the vertical and transverse
direction.
• It relates to a planer and like a planning
machine. This machine has a cross rail capable
of being raised or lowered carrying the cutters.
It has their heads, and the saddles, all supported
by rigid uprights.
• This arrangement of driving multiple cutter
spindles enables a number of work surfaces to
be machined. Thereby it obtains the great
reduction in production time.
ROTARY TABLE MILLING MACHINE :
• Here the table is circular in nature and rotates about a vertical
axis. Here cutters are set at different heights. Which results in
one cutter roughing the workpiece and other one cutter
finishing them.
• The advantage of this machine is that continuous loading and
unloading of workpieces can be done by the operator, while is
in progress.
PLANETARY MILLING MACHINE :
• Here workpiece is held stationary while the revolving cutter.
The cutter moves in a travelling path to finish a cylindrical
surface on the workpiece either internally or externally. This
machine is also adapted for milling internal and external
threads.
MAIN COMPONENTS :
1.
2.
3.
4.
5.
6.
7.
8.
Base .
Column.
Saddle.
Table.
Overhanging arm.
Front brace.
Spindle.
Arbor.
PARTS CLASIFICATION :
BASE :
• The base of the machine is grey iron casting and serves as a foundation member for all
other parts which rests on it.
• The base carries the column at its one end. In some other machines, the base is hollow
and works as a reservoir for cutting fluid.
COLUMN:
• The column is the main supporting frame mounted on the base.
• It is box-shaped and houses all the driving mechanism for the spindle and feed table.
• The front vertical face of the column is precisely machined and is equipped with dovetail
guideways for supporting the knee.
• The top of the column is finished to hold an overarm that extends beyond the front of the
machine.
KNEE:
• The knee is a fixed grey iron casting that slides up and down on the vertical ways of
the column face.
• The adjustment of height is affected by an elevating screw mounted on the base that
also supports the knee.
• The knee houses the feed mechanism of the table and controls to operate it.
• The top face of the knee forms a slideway for the saddle that gives cross travel to the
table.
SADDLE:
• On the top of the knee is placed the saddle, which slides on guideways set exactly at 90
degrees to the column face.
• A crossfeed screw near the top of the knee engages a nut on the bottom of the saddle to
move it horizontally, by hand or power, to apply cross-feed.
• The top of the saddle is precisely machined to provide guideways for the table.
TABLE:
• It rests on guideways on the saddle and travels longitudinally.
• The top of the table is finished accurately and T-slots are provided for clamping the
work and other fixtures.
• A lead-screw is provided under the table that engages with a nut on the saddle, it
helps to move the table horizontally by hand or power.
• The longitudinal travel of the table possibly limited by fixing trip dogs on the side of
the table.
• In universal machines, the table may also be swivelled horizontally. For this purpose,
the table is mounted on a circular base, which in its turn is mounted on the saddle.
• The circular base is graduated in degree .
OVERHANGING ARM :
• Overhanging arm act as a support for the arbor.
• It is mounted on the top of the column extends outwards the column face and works as
bearing support for the other end of the arbor.
• The Overhanging arm is adjustable so that the bearing support may be provided nearest
to the cutter.
• More than one bearing support can be provided for the arbor.
SPINDLE:
• The spindle of the machine is located in the upper part of the column and receives
power from the motor through belts, gears, and clutches and transmit it to the arbor.
• The front end of the spindle just projects from the column face and is provided with a
tapered hole into which various cutting tools and arbor may be inserted.
ARBOR:
• Arbor is an extension of the machine spindle on which milling cutters are securely
mounted and rotated.
• These are made with taper shanks for proper alignment with the machine spindles
having taper holes at their nose.
• The taper shank of the arbor match to the Morse taper or self-release taper whose
value is 7:24.
• The arbor may be supported at the farthest end from the overhanging arm or maybe of
cantilever type which is called stub arbor.
ADVANTAGES:
• Milling machines can help to increase productivity as they are able to perform
multiple operations in a single setup.
• Milling machines can also help to increase accuracy as they are able to produce
parts that are more precise than those produced by other methods.
• Another advantage of milling machines is that they are very versatile and flexible.
• Milling machines is that they can help to reduce waste. This is because when parts
are milled correctly, there is very little material waste.
DISADVANTAGES :
• Milling machines can be very loud, which can be disruptive to both the operator
and those nearby.
• Milling machines generate a lot of dust.
• Milling machines are typically very expensive, which may make them
unaffordable for some people.
• Milling machines require a high level of skill to operate, which may make them
difficult to use for some people.
• Milling machines require a lot of space, which may not be available in all shops or
homes.
CONCLUSION :
• All in all, milling machines have many advantages that make them well worth the
investment for any business looking for precise results from their cutting
operations, but there are also some disadvantages that must be considered before
investing in one of these pieces of equipment, including setup times and
maintenance costs along with slower speeds compared to other types of machinery
like laser cutters or water jet cutters. Ultimately the decision comes down to what
type of application you’re looking for – if accuracy is more important than speed,
then investing in a milling machine might be the right choice, but if you need
faster results, then another type of machinery might make more sense for your
particular needs.