A power point presentation regarding Machining & Material Removal

2.  Turning
 Boring
 Drilling
 Milling
 Grinding
 Electrochemical
 Chemical
 Gears & Bearings

3.  Turning is a machining
process to produce parts
round in shape by a single
point tool on lathes.
 The tool is fed is either
linearly in the directon
parallel or perpendicular to
the axis of rotation of the
workpiece, or along a
specified path to produce
complex rotational shapes.
 The primary motion of
cutting in turning is the
rotation of the workpiece,
and the secondary motion of
cutting is the feed motion.

4.  Boring is a process of producing
circular internal profiles on a
hole.
 It uses single point cutting tool
called a boring bar. In Boring,
the boring bar can be rotated or
the workpart can be rotated.
 Machine tools which rotate the
boring bar against a stationary
workpiece are called boring
machines (also boring mills).
 Boring can be accomplished on
a turning machine with a
stationary boring bar positioned
in the tool post and rotating
workpiece held in the lathe
chuck as shown in figure.

5.  Drilling is the process of producing
round holes in a solid material or
enlarging existing holes with the use
of multi-tooth cutting tools called
drills or drill bits.
 In drilling, the rotating tool is fed
vertically into the stationary
workpiece to create a hole.
 A drill press is specifically designed
for drilling, but milling machines and
turning machines can also perform
this process. Drilling operations such
as counterboring, countersinking, rea
ming, and tapping can be used to
create recessed holes, high precision
holes, and threaded holes. Other
multi-point cutting processes exist
that do not require the tool to rotate,
such as broaching and sawing.

7.  Milling is a process of producing flat &
complex shapes with the use of multi-tooth
cutting tool which is called milling cutter
and the cutting edges are called teeth.
 The axis of rotation of the cutting tool is
perpendicular to the direction of feed,
either parallel or perpendicular to the
machined surface.
 Milling is an interrupted cutting operation;
the teeth of the milling cutter enter & exit
the work during each revolution. This
interrupted cutting action subjects the teeth
to a cycle of impact force and thermal shock
on every rotation.
 The tool material & the cutter must be
designed to withstand these conditions.
Cutting fluids are essential for most milling
operations.

8. A. In Down Milling, the cutter
rotation is in the same
direction as the motion of
the workpiece being fed.
B. In Up (Conventional)
Milling the workpiece is
moving towards the cutter
opposing the cutter
direction of rotation.
A. SLAB MILLING
B. FACE MILLING
C. END MILLING
TYPES OF MILLING:

9.  Grinding is an abrasive
machining process that uses
a grinding wheel as the cutting
tool.
 It is the only economical method
of cutting hard material like
hardened steel.
 It produces very smooth surface ,
suitable for bearing surface.
 Surface pressure is minimum in
grinding.
 It is suitable for light work,
which will spring away from the
cutting tool in the other
machining processes.

10. CENTERLESS GRINDING

11.  The wheels and workpiece are
electrically conductive.
 Wheels used last for many grindings -
typically 90% of the metal is removed
by electrolysis and 10% from the
abrasive grinding wheel.
 Capable of producing smooth edges
without the burrs caused by mechanical
grinding.
 Does not produce appreciable heat that
would distort workpiece.
 Decomposes the workpiece and
deposits them into the electrolyte
solution. The most common electrolytes
are sodium chloride and sodium
nitrate at concentrations of 2 lbs. per
gallon

12.  Machining processes that involve chip formation
have a number of limitations
Large amounts of energy
Unwanted distortion
Residual stresses
Burrs
Delicate or complex geometries may be difficult or
impossible

13. Complex geometries are possible
Extreme surface finish
Tight tolerances
Delicate components
Little or no burring or residual stresses
Brittle materials with high hardness can be machined
Microelectronic or integrated circuits (IC) are possible
to mass produce

14.  An electrolytic reaction
takes place at workpiece
surface for removal of
material.
 Electrochemical
machining (ECM) removes
material by anodic
dissolution with a rapidly
flowing electrolyte.
 The tool is the cathode
and the workpiece is the
anode.

15. Advantages and Disadvantages of
Electrochemical Machining:
 Advantages
ECM is well suited for the
machining of complex two-
dimensional shapes
Delicate parts may be made
Difficult - to machine
geometries
Poorly machinable materials
may be processed
Little or no tool wear
 Disadvantages
Initial tooling can be
timely and costly
Environmentally
harmful by-products

16.  Chemical reaction between a liquid
reagent and workpiece results in
etching.
 Typically involves metals, but
ceramics and glasses may be
etched
 Material is removed from a
workpiece by selectively exposing it
to a chemical reagent or etchant.
 Gel milling - gel is applied to the
workpiece in gel form.
 Maskant - selected areas are
covered and the remaining
surfaces are exposed to the
etchant. This is the most
common method of CHM.
Fig: Steps required to produce a stepped
contour by chemical machining.

17. Advantages and Disadvantages of
Chemical Machining:
 Advantages
Process is relatively
simple
Does not require highly
skilled labor
Induces no stress or cold
working in the metal
Can be applied to almost
any metal
Large areas
Virtually unlimited shape
Thin sections
 Disadvantages
Requires the handling of
dangerous chemicals
Disposal of potentially
harmful byproducts
Metal removal rate is
slow

18.  Because of their capability for
transmitting motion & power,
gears are among the most
important of all machine elements.
 Special attention is paid to gear
manufacturing because of the
specific requirements to the gears.
 The gear tooth flanks have a
complex & precise shape with high
requirements to the surface finish.
 Gears can be manufactured by
most of manufacturing processes
such as casting, forging,
extrusion, powder metallurgy,
blanking.
 But as a rule, machining is applied
to achieve the final dimensions,
shape and surface finish in the
gear.

22.  The main function of a rotating shaft is to
transmit power from one end of the line to
the other.
 It needs a good support to ensure stability
and frictionless rotation. The support for
the shaft is known as “bearing”.
 The shaft has a “running fit” in a bearing.
All bearing are provided some lubrication
arrangement to reduced friction between
shaft and bearing.

23.  Plain or slider bearing : -
In which the rotating shaft
has a sliding contact with
the bearing which is held
stationary . Due to large
contact area friction
between mating parts is
high requiring greater
lubrication.
 Rolling or anti-friction
bearing : -
Due to less contact area
rolling friction is much
lesser than the sliding
friction , hence these
bearings are also known as
antifriction bearing.