Military Institute of Science and Technology
Department of Industrial & Production Engineering
Q.1. Compare soldering, brazing and welding. 10
Answer:
No
Welding Soldering Brazing
.
Welding joints are
Soldering joints are Brazing joints are
strongest joints used to
weakest joints out of weaker than welding
bear the load. Strength
three. Not meant to bear joints but stronger than
1 of the welded portion of
the load. Use to make soldering joints. This
joint is usually more
electrical contacts can be used to bear the
than the strength of base
generally. load up to some extent.
metal.
Temperature
Temperature required is
requirement is up to Temperature may go to
2 3800°C in welding
450°C in soldering 600°C in brazing joints.
joints.
joints.
To join work pieces Work pieces are heated
Heating of the work
3 need to be heated till but below their melting
pieces is not required.
their melting point. point.
Mechanical properties of May change in
No change in
base metal may change mechanical properties
4 mechanical properties
at the joint due to of joint but it is almost
after joining.
heating and cooling. negligible.
Heat cost is involved Cost involved and skill Cost involved and sill
5 and high skill level is requirements are very required are in between
required. low. other two.
Heat treatment is
generally required to No heat treatment is No heat treatment is
6
eliminate undesirable required. required after brazing.
effects of welding.
Q.2. Define measurement error. Mention various sources of measurement error. 10
Answer: Measurement error is the difference between the true value of the size and
the value found by measurement.
Error = True Size – Actual Size
Measurement errors arise for many reasons. Here are just a few:
Calibration Errors: due to nonlinearity or errors in the calibration method.
Loading or Intrusion Errors: the sensor may actually change the very thing it
is trying to measure.
Spatial Errors: arise when a quantity varies in space, but a measurement is
taken only at one location (e.g. temperature in a room - usually the top of a
room is warmer than the bottom).
Human Errors: arise if a person consistently reads a scale on the low side, for
example.
Defective Equipment Errors: arise if the instrument consistently reads too
high or too low due to some internal problem or damage.
Zero Error: The instrument does not read zero when the input is zero. Zero
error is a type of bias error that offsets all measurements taken by the
instrument, but can usually be corrected by some kind of zero offset adjustment.
Linearity Error: The output deviates from the calibrated linear relationship
between the input and the output. Linearity error is a type of bias error, but
unlike zero error, the degree of error varies with the magnitude of the
Q.3. Mention the types of cutting fluid. List the essential properties of good cutting 10
fluid.
Answer: Cutting fluids are used in metal machining for a variety of reasons such as
improving tool life, reducing workpiece thermal deformation, improving surface finish
and flushing away chips from the cutting zone. Practically all cutting fluids presently in
use fall into one of four categories:
Straight oils
Soluble oils
Semi-synthetic fluids
Synthetic fluids
A good type of cutting fluid should possess certain desired properties such as:
Good cooling capacity and lubricating qualities
Rust resistance and stability- for long life
Resistance to rancidity and foaming
Non-toxic
Transparent-to allow the operator to see the work clearly during machining
Relatively low viscosity-to permit the chips and dirt to settle quickly
Nonflammable-to avoid burning easily and should be non-combustible
Ability to dispose in an environmentally responsible way.
In addition, it should not smoke excessively, form gummy deposit which may
cause machine slide to become sticky, or clog the circulating system.
Q.4 Discuss the assumptions in Linear Programming problem formulation. 10
Answer:
Assumptions in Linear Programming formulation are given below:
Proportionality assumption: The contribution of each activity to the value of
the objective function Z (and LHS of functional constraint) is proportional to the
level of the activity.
Additivity assumption: Every function in a linear programming model is the
sum of the individual contributions of the respective activities.
Divisibility assumption: Decision variables in a linear programming model are
allowed to have any values, including non-integer values that satisfy the
functional and non-negativity constraints.
Certainty assumption: The value assigned to each parameter of a linear
programming model is assumed to be a known constant.
Q.5. Examine the properties that a conveyer belt should essentially possess. 10
Answer:
Properties of a conveyer belt:
Low hygroscopicity
High strength
Low self-weight
Small specific elongation
High flexibility
High resistance to ply separation
Long service life
Q.6. Describe ‘ABC Analysis’? How do you use it for inventory management? 10
Answer: ABC analysis is a type of inventory categorization method in which inventory
is divided into three categories, A, B, and C, in descending value. A has the highest
value items, B is lower value than A, and C has the lowest value.
Inventory management and optimization in general is critical for business to help keep
their costs under control. ABC analysis works towards this goal by letting management
focus most of their attention on the few highest value goods (the A-items) and not on
the many low value, trivial goods (the C-items).
ABC analysis may be seen to share similar ideas as the Pareto principle, which states
that 80% of overall consumption value comes from only 20% of items. Plainly, it
means that 20% of your products will bring in 80% of your revenues.
ABC analysis works by breaking it down in the following ways:
A-items: 20% of all goods contribute to 70-80% of the annual consumption
value of the items
B-items: 30% of all goods contribute to 15-25% of the annual consumption
value of the items
C-items: 50% of all goods contribute only 5% of the annual consumption value
of the items
Q.7. Define Zero Quality Control (ZQC). Explain the cost of quality. 10
Answer: Zero Quality Control is a method, popularized by the quality guru Shigeo
Shingo that proposes removing the need for inspection by eliminating the possibility of
human error. Mr. Shingo was a proponent of PokaYoke or Mistake Proofing processes
which is a key component to removing the need for inspection. The idea is that by
removing the root causes of errors, it is possible to achieve zero defects.
Cost of quality fall into four categories, which are:
Prevention costs. The cost in order to keep a quality problem from
occurring. It is the least expensive type of quality cost, and so is highly
recommended. A focus on prevention tends to reduce preventable scrap costs,
because the scrap never occurs.
Appraisal costs. One can incur appraisal cost in order to keep a quality
problem from occurring. This is done through a variety of inspections.
Internal failure costs. An internal failure cost is incurred when a defective
product is produced. This appears in the form of scrapped or reworked goods. The
cost of reworking goods is part of this cost.
External failure costs. One can incur an external failure cost when a
defective product was produced, but now the cost is much more extensive, because
it includes the cost of product recalls, warranty claims, field service, and
potentially even the legal costs associated with customer lawsuits.
Q.8 Describe the basic elements of a project planning. 10
Answer:
Elements of Project Plan
The process of developing the project plan varies from organization to organization, but
any project plan must contain the following elements:
Overview: short summary of the objectives and scope of the project.
Objectives: This contains a more detailed statement of goals or target to be
achieved.
General Approach: This section describes both the managerial and the
technical approaches to the work.
Contractual Aspects: includes a complete list and description of all reporting
requirements.
Schedules: plan showing when individual or group activities will be started and
completed
Budget: plan expenditures required to achieve objectives.
Resources: resource requirements are detailed by tasks.
Personnel: this section lists the expected personnel requirements of the project.
Risk management plan: covers any type of unwanted problems that could
affect the project.
Evaluation: need to evaluate financially and technically against standards and
by methods established at the project’s inception.
Q.9. Define Machine Home and Part Origin. Mention the advantages of Computer 10
Numerical Control (CNC) over Numerical Control (NC).
Answer:
Machine Home (Machine Zero) – a location set once by the machine
manufacturer.
Part Origin (Part Zero) – a location determined by the NC part programmer.
Advantages of CNC over NC:
New machine functions can be “easily” added to a CNC system.
A CNC controller can store, edit, and execute programmed instructions.
Direct Numerical Control (DNC) – several CNC machines can be linked
together to a main computer (programs can be downloaded to any CNC machine
in the network).
Distributive Numerical Control – several DNC systems can be networked to
form a large distributive numerical control system.
Q.10. Mention the application of following lathe accessories: 10
i. Lathe Chuck
ii. Faceplate
iii. Mandrels
iv. Rests
Answer:
Lathe Chuck:
Used for holding and rotating a work piece in lathe. Components of any regular of
irregular can be held. Attached to the spindle with bolts with the back plate screwed on
spindle nose. Mainly two types: universal or three jaw chuck and four jaw chuck
(independent).
Faceplate:
Used for holding the chuck in lathe. It is very heavy and has strong ribs. Nuts and bolts
are used for clamping the chuck with it. Has thread in a hole in center so that it can be
fit into the spindle nose.
Mandrels:
It is a shaft made of high carbon steel and mounted between the centers. It is used for
holding the pre drilled work pieces for outside machining. It is always rotated with the
help of a dog and it is never placed in a chuck.
Rests:
It is used to support a long slender job, which is turned between centers. It prevents the
bending of work piece which is cause due to its own weight and vibrations of the
cutting forces. It is generally used when length to diameter ratio is around 1: 10-12.
Mainly of two types: steady and follower.
