in a temporary memory known as buffer
memory. The memory unit will provide
the information blocks to the processing
unit in the desired sequence. Processing
unit The processing unit serves as a link
between the memory unit and output
channels. The process
drilling machine table. 20. What type of
surfaces are machined on a shaper? 21.
Which part of the shaper is involved in
automatic lifting of the tool during the
return stroke of the ram? 22. Name one
artificial abrasive. 23. Name the grinding
memory unit b. feedback unit c.
processors d. driving devices 6.
Transducers are a. feedback devices b.
memory unit c. output channels d.
processors 7. When a NC system does
not have any feedback arrangement, it is
known as a. positioning system b.
tools. The affected parts are to be
replaced if necessary. Backlash Some
slackness is observed in holding of parts,
meshing gears or bolt and nut assembly.
This slackness is known as backlash. If
the amount of backlash is more in the
case of mating gears,
on each other. It generates heat and the
parts get damaged. In order to keep the
machine tools accurate and durable, it is
necessary to apply lubricants between
mating parts. It will reduce friction and
wear is minimised. Lubrication is the
nerve centre o
ADAPT, EXAPT, SPLIT, PROMPT are some
of the high level languages used for
writing NC programs. 9.9 Advancements
in NC machines After the modern microprocessor based computers took control
of the NC system, the technology in this
field has grown tremendous
the feedback system a. Open loop
system b. Closed loop system D.
According to axis identification a. 2- axis
b. 3- axis c. 4- axis d. 5- axis 9.5 Motion
control system The cutting tool and the
work are located at certain postions in
NC machine. During the
welding torch through regulators. The
colour of the hose from the oxygen
cylinder is black and the one from the
acetylene cylinder is red. These hoses
carry the gases to the welding torch. Gas
welding kit is shown in Fig. 8.4 8.8.5
Welding torch Oxygen an
management has to pay the labourers
their wages. It will also be earning a bad
name due to non - deliverance of the
products to its customers. So, it is
necessary to plan the preventive
maintenance program to avoid such
losses. Even if the machine tools a
control valve Acetylene control valve
Hoses 8.8.7 Welding gloves Protective
hand gloves are used by the operator to
prevent possible damages that may be
caused by high temperatures and metal
splashes during welding. 8.9.8 Spark
lighter Spark lighter is us
can be made on the surfaces of different
cutting tools and cutters. Fig. 8.9 shows
hard facing. 8.15.4 Soldering Two parts
made of similar or dissimilar metals are
joined by a solder made of a fusible
alloy. Solder is an alloy made of Tin and
Lead. The me
format is used. In this system, only two
digits (0 & 1) are used and the base is 2.
All instructions and informations are
converted as numbers consisting of
digits 0 and 1. It becomes easy to record
the informations on punched tapes or
punched cards in th
arc welding d. solid state welding 2. The
working temperature of arc welding is a.
100C-150C b. 50C-100C c. 5000C6000C d. 150C-200C 3. The pressure
of oxygen in the cylinder of gas welding
equipment is a.16 kg/cm2 b. 125kg/cm2
c. 100kg/cm2 d. 14kg/cm2 4.
container having oil is placed above the
bearing. The wick connects the container
and the part to be lubricated. This
lubrication enables the oil to flow from
the container to the required place. Wick
lubrication is illustrated in Fig. 10.2.
of the welding joint is increased by
adding Nickel or Chromium in filler rods.
A thin coat of copper is provided on the
filler rods to prevent the molten metal
from reacting with atmospheric oxygen.
Flux may be applied either in powdered
form or liquid fo
the molten filler metal is applied
between the parts to make the joint. In
this method, the metal parts are not
melted. The process of brazing is
illustrated in Fig. 8.11. Fig 8.11 Brazing
Filler rod Brazing tip Brazing torch Work
8.16 Types welded joints
Driving devices consist of different types
of motors and gear trains. They convert
the instructions form the MCU into
accurate mechanical displacements of
the machine tool slides. The motors may
be electrical, hydraulic or pneumatic.
Electrical motors are
(MCU) Machine Control Unit consists of
electronic circuits (hardware) that are
useful in reading and interpreting the
instructions (NC program) fed by means
of input media and convert them into
mechanical actions of the machine tool.
Generally, the MCU ma
have any feedback arrangement, it is
known as open loop system. Actual
output movement is not directly
measured and checked with the desired
movement. 9.6.2 Closed loop system In
this system, the final movements
(spindle speed and slide displacement)
milling cutter in one minute is known as
a. cutting speed b. depth of cut c. spindle
speed d. feed 11. Impeller is a part found
in a. reciprocating pump b. gear pump c.
centrifugal pump d. vane pump 226 12.
Starter used for motors of capacity upto
5 hp is
the machine tool to produce the desired
part. 201 In performing all the above
operations, the NC machine may have
the following elements: 1. Software 2.
Machine Control Unit 3. Driving devices
4. Manual control unit 5. Machine tool
9.3.1 Software A series
reducing flame. The supply of acetylene
will be more than oxygen to produce this
flame. Carburising flame consists of
three zones namely, 1. Sharp inner cone
2. White intermediate cone 3. Bluish
outer cone Carburising flame is useful in
welding low carbon
Adaptive control is a system in which an
important feature of decision making is
employed during machining. When a
component is being manufactured, some
important process variables like torque,
force and temperature are measured.
These values are compared
by keeping the metal plates at
perpendicular (90) to each other. Sheets
with thickners over 3 mm only are
welded by this type 197 Fig 8.12 Types of
welded joints Butt joint Lap joint T joint
Corner joint Flange joint 8.16.4 Corner
joint Two metal sheets k
correct option 1. Lathe was first
developed by a. Henry Maudslay b. Eli
Whitney c. James Nasmith d. Michael
Faraday 2.Turret and capstan lathes are
classified under a. automatic lathes b.
semi-automatic lathes c. bench lathe d.
tool room lathe 3. The lip
4. What are the types of electrodes? 5.
Name the three types of flames
generated in gas welding? 6. Write short
notes on filler rods used in gas welding?
7. Write any four advantages of gas
welding? 199 8. What are the limitations
of gas welding? 9. What
beings in the machining process is
substituted by some operating
instructions in a coded form. This coding
otherwise known as part program is
stored in cards or tapes. Getting the
required instructions from these input
media, the machine carries out diffe
quality of the product also becomes
better. 11. Operator errors are
substantially reduced and so very less
scrap is produced. 12. As a single
operator can supervise several machines
at a time, the labour cost is reduced. 9.8
Programming for CNC machines B
the task performed to make the machine
tools work perfectly is called
Maintenance. This is achieved by
ensuring that machine tools, cutting
tools and measuring instruments
function properly without any fault.
10.2. The objective of Maintenance The
gun Handle Grease filling port Grease
outlet Lubricating oil and grease are
manufactured under several trade
names by the Indian oil companies.
Suitable lubricants are used for specific
purposes. 10.7 Central maintenance
department The primary aim of
lubrication? 12. What are the parts
which need to be lubricated? III. Answer
the following questions in about a page
1. What are the objectives of
lubrication? 2. Explain Ring lubication
with a diagram. 3. Explain Wick
lubrication with a diagram. 4. Greas
sentences 1. Define - Numerical Control.
2. What do you mean by software of a
NC system? 3. What is Machine Control
Unit? 4. What are the types of MCU? 5.
Mention the functions of input reading
unit? 6. How is processing unit important
in a NC system? 7.
also to be kept ready. 9. Annual budget
for the maintenance work should be
prepared atleast six months or one year
in advance. 10.10 Materials and
instruments needed for doing
maintenance 1. Steel rule 2. Try-square
3. Calipers 4. Micrometer 5. Vernier
Name any two points in specifying the
size of a shaping machine. 37. What is
centreless grinding? 38. What is glazing?
39. What is milling? 40. What is the use
of indexing head? 41. Mention the types
of hydraulic pumps. 42. What are the
safety devices fit
manual control unit may be a part of the
MCU (machine control unit) The
operator use the manual contrl unit to 1.
switch on and off the machine 2. load
and unload the workpieces and 3.
change the tools in certain types of
machines 9.3.5 Machine tool It is