(SEM VII) THEORY EXAMINATION 2023-24 MATHEMATICAL MODELING OF MANUFACTURING PROCESSES

KME073 – MATHEMATICAL MODELING OF MANUFACTURING PROCESSES

B.Tech (SEM VII) – Theory Examination
Time: 3 Hours | Max Marks: 100

SECTION A

(Attempt all questions in brief – 2 marks each)

a. Enlist the four mechanical properties of materials.

Four mechanical properties are:                                 Strength

Hardness                                                                     Ductility

Toughness

b. Distinguish between recrystallization and melting point temperature.

Recrystallization temperature is the minimum temperature at which new strain-free grains form in a cold-worked metal.

Melting point temperature is the temperature at which a solid metal changes into liquid state.

c. Distinguish between linear and non-linear models.

Linear model: Output is directly proportional to input; equations are linear.

Non-linear model: Output is not proportional to input; equations involve powers, exponentials, or products of variables.

d. Define the term tool life.

Tool life is the duration for which a cutting tool performs satisfactorily before it becomes dull and requires replacement or re-sharpening.

e. Define bulk deformation of metals.

Bulk deformation refers to manufacturing processes in which metals undergo large plastic deformation, such as rolling, forging, extrusion, and drawing.

f. What do you understand by fusion welding?

Fusion welding is a welding process in which base metals are melted with or without filler material to form a joint upon solidification.

g. What do you mean by liquid phase sintering?

Liquid phase sintering is a powder metallurgy process where a liquid phase forms during sintering, enhancing bonding and densification of particles.

h. Differentiate between casting and coating.

Casting: Molten metal is poured into a mold to form a component.

Coating: A thin layer of material is applied on a surface to improve properties like corrosion resistance or wear resistance.

i. Distinguish between macro machining and micro machining.

Macro machining: Conventional machining with millimeter-scale features.

Micro machining: Machining of features in micron or sub-micron scale with high precision.

j. Write down the objectives of heat transfer.

Objectives of heat transfer are:                                   To control temperature

To improve energy efficiency                                      To enhance material properties

To ensure safe and efficient process operation

SECTION B

(Attempt any three – answers provided for ALL)

2(a). What do you understand by modeling? Explain types of mathematical models used in manufacturing.

Modeling is the process of representing a real manufacturing system using mathematical equations to analyze, predict, and optimize performance.

Types of mathematical models:                                  Empirical models: Based on experimental data

Analytical models: Derived using physical laws           Deterministic models: No randomness involved

Stochastic models: Include uncertainty and randomness

Linear and non-linear models

Models help in process optimization and cost reduction.

2(b). Calculate the specific cutting energy of material in turning process.

Specific cutting energy is defined as the energy required to remove a unit volume of material.

Specific Cutting Energy=Cutting Force×Cutting SpeedMaterial Removal Rate\text{Specific Cutting Energy} = \frac{\text{Cutting Force} \times \text{Cutting Speed}}{\text{Material Removal Rate}}Specific Cutting Energy=Material Removal RateCutting Force×Cutting Speed​

It depends on material properties, cutting conditions, and tool geometry. It is used to estimate power requirements in machining.

2(c). Explain the different types of welding heat source.

Welding heat sources include:

Electrical arc: Used in arc welding                                Gas flame: Used in oxy-fuel welding

Resistance heating: Used in spot welding                   Laser beam: High energy density and precision

Electron beam: Deep penetration welding                  Each source differs in heat intensity and application.

2(d). Explain steps of powder metallurgy and compare with additive manufacturing.

Steps of Powder Metallurgy:                                      Powder production

Blending and mixing                                                      Compaction

Sintering                                                                         Finishing

Comparison:

Powder metallurgy uses molds; additive manufacturing builds layer by layer.

Additive manufacturing allows complex shapes.

Powder metallurgy is suitable for mass production.

2(e). Explain micro manufacturing processes and applications.

Micro manufacturing involves fabrication of micro-scale components using processes such as:

Micro machining                                                            Micro molding

Micro EDM                                                                     Micro additive manufacturing

Applications:                                                                Medical devices

MEMS                                                                             Micro electronics

Precision instruments

SECTION C

3(a). What are engineered materials? Explain their properties.

Engineered materials are materials designed to achieve specific mechanical, thermal, or electrical properties.

Properties include:                                                   High strength-to-weight ratio

Corrosion resistance                                                   Thermal stability

Tailored mechanical behavior                                      Examples include composites and smart materials.

3(b). Short note on solid phase transformation.

Solid phase transformation involves change in crystal structure without melting. Examples include austenite to martensite transformation in steel. It significantly affects mechanical properties.

4(a). Explain material removal mechanism of Electro-Chemical Machining (ECM) and role of electrolyte.

In ECM, material is removed by electrochemical dissolution based on Faraday’s laws.

Role of electrolyte:                                                   Conducts electricity

Removes dissolved metal ions                                    Maintains temperature

Improves machining accuracy

4(b). Explain heat generation and dissipation in metal cutting zones.

Primary shear zone: Heat due to plastic deformation

Secondary zone: Heat due to friction between tool and chip

Tertiary zone: Heat due to tool-workpiece contact

Proper heat dissipation improves tool life.

5(a). Principle of solid-state welding and difference from arc welding.

Solid-state welding principle: Joining without melting by applying pressure and/or heat.

Difference:

Solid-state welding does not melt metal                          Arc welding melts metal using electric arc

Solid-state welding produces stronger joints

5(b). Classify sheet metal forming and explain deep drawing.

Sheet metal forming processes:

Bending                                                                             Drawing

Stretch forming                                                                 Spinning

Deep drawing: A flat sheet is drawn into a die cavity to form cup-shaped components. It is widely used in automotive industries.

6(a). Principle, classification, and challenges of additive manufacturing.

Principle: Parts are built layer by layer from digital models.

Classification:                                                                   Material extrusion

Powder bed fusion                                                              Binder jetting

Vat photopolymerization

Challenges:                                                                       High cost

Limited material options                                                    Surface finish issues

6(b). What is coating? Explain one coating method.

Coating is the process of applying a thin protective layer on a surface.

Thermal spraying: Molten material is sprayed onto the surface to improve wear and corrosion resistance.

7(a). Manufacturing technology shift from micro to nano and challenges.

Nano manufacturing deals with features below 100 nm.

Challenges:                                                                      Tool fabrication

Precision control                                                               Measurement accuracy

High cost

7(b). Effect of heat treatment on steel microstructure.

Heat treatment processes like annealing, quenching, and tempering alter grain size and phase distribution, improving hardness, strength, and toughness.