INDUSTRIAL
TRAINING REPORT
Training
Taken at:
LAKSHMI
MACHINE WORKS Ltd, COIMBATORE
&
SIMTA Ltd,
COIMBATORE
SUBMITTED
BY
SATHYA PRAKASH.G
2K2-177
DEPARTMENT OF MECHANICAL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
KURUKSHETRA
PLANO
MILLER AND UNIVERSAL MILLING MACHINE:
These two machines are mainly employed for cutting
beds for Lathe, VMC, and HMC. Both the machines can hold 60 tools that
facilitate the continuous operation of the machines. Both the machines are
Computer operating (CNC) so the programs can be developed for each types of bed
and stored in the computer. Another main advantage in CNC is that, if we
connect two computers by LAN connection, we can access the programmes of other
computers also.
And while
working for a particular bed say Pilatus (Lathe), the casted part has to be
fitted and we have to run the program. Then within one hour the bed would be
ready. In this operation, we need at least one worker to take care of the
coolant flow in the right cutting area.
Both the machines have capacity of finishing one bed in an hour if
working under normal conditions.
GRINDING:
Grinding
is a finishing process used to improve surface finish, abrade hard materials,
and tighten the tolerance on flat and cylindrical surfaces by removing a small
amount of material.
In
grinding, an abrasive material rubs against the metal part and removes tiny
pieces of material. The abrasive material is typically on the surface of a
wheel or belt and abrades material in a way similar to sanding. On a
microscopic scale, the chip formation in grinding is the same as that found in
other machining processes. The abrasive action of grinding generates excessive
heat so that flooding of the cutting area with fluid is necessary. Almost any
material can be ground - aluminium, steel, ceramics, even diamond or glass.
When we grind a material we would see some sparks produced around work-piece. The sparks are a result of small fragments of metal - grinding
chips - being rapidly sheared from the surface at high temperatures and burning
in the atmosphere. Since grinding chips are burning in atmosphere, high
temperature is produced around the work-piece, so we should use high efficient
coolant with constant high flow rate of coolant.
It is a highly effective method of achieving
desired metal removal and surface finish in a wide range of common
applications, such as: grinding down and smoothing weld seams, cleaning metal
before welding, removing imperfections, and smoothing rough surfaces on
castings.
Reasons for grinding are:
1. The material is too hard to be machined economically. (The material
may have been hardened in order to produce a low-wear finish, such as that in a
bearing raceway.)
2. Tolerances required preclude machining. Grinding can produce
flatness tolerances of less than ±0.0025 mm (±0.0001 in) on a 127 x 127 mm (5 x
5 in) steel surface if the surface is adequately supported.
3.
Machining removes excessive material.
DEEP
HOLE DRILLING:
Originally a time-consuming and costly
process, today's technological advances make it a highly efficient
manufacturing operation in all metal cutting industries. Gun drilling is an
ideal solution for most deep and precision drilling projects. This high
precision operation produces accurate, repeatable holes, with excellent surface
finishes. Gun drills hold location to precise tolerances, are sized to exact
specifications, produce burr free holes, and can be formed to produce specific
shapes in blind holes with minimal machine adaptation.
A typical gun drill consists of three
parts: a carbide tip, a heat treated alloy shank, and a steel driver. All are
typically silver brazed together, and are designed to allow coolant to pass
through its entire length. The shank must be properly formed, heat treated, and
aligned to absorb cutting torque, sagging, and the whipping associated with
high RPM's.
The drill is positioned and held in the
spindle nose, then guided into the work-piece through a pre-started hole or
guide bushing that prevents vibration and ensures accuracy. Gun drill cutting
edges form thin, curled chips that are carried away from the bore by
high-pressure lubricant. The off-centre design of the cutting edges creates
pressure within the bore that is carried by pads behind the drill tip. The
coolant that flushes the chips also lubricates these pads, which burnish the
surface and develop the fine finish.
Specifically designed to provide the
optimum conditions for operating the gun drill, the deep hole drilling machine
is equipped with a high pressure pump that delivers lubricant to the rear of
the drill. Generally, the drill is held stationary but work piece is rotating
and with the advancement of the drill, deep hole is made.
The gun drill is supported by anti-whip
devices along the shank length and at the rear of the chip box. The chip box
contains a chip deflector and a front end bushing which guides the drill into
the work-piece. The chip box also contains escaping chips and lubricant, which
are separated and filtered.