THEORY EXAMINATION (SEM–VI) 2016-17 UNCONVENTIONAL MANUFACTURING PROCESSES

UNCONVENTIONAL MANUFACTURING PROCESSES (EME012)

B.Tech – Semester VI
 

Time: 3 Hours | Max Marks: 100

SECTION – A (10 × 2 = 20 marks)

(Attempt all questions)

(a) What is cladding?

Cladding is a process in which a layer of corrosion-resistant or wear-resistant material is bonded on the surface of a base metal to improve surface properties.

(b) What are the different types of abrasives used in AJM?

The abrasives used in Abrasive Jet Machining are silicon carbide, aluminium oxide, glass beads, and sodium bicarbonate.

(c) What are the characteristics of laser used in laser machining?

Laser used in laser machining has high coherence, high intensity, monochromatic nature, and can be focused to a very small spot.

(d) Name some of the tool materials used in EDM.

Tool materials used in EDM include copper, graphite, brass, tungsten, and copper-tungsten alloys.

(e) What properties are expected from the electrolyte used in ECM?

The electrolyte should have high electrical conductivity, good chemical stability, low viscosity, non-toxic nature, and high corrosion resistance.

(f) Enlist the limitations of conventional machining processes.

Conventional machining is limited in machining very hard materials, intricate shapes, high tool wear, thermal damage, and low accuracy for micro-features.

(g) How are non-traditional machining processes classified?

They are classified based on energy used, such as mechanical, thermal, electro-chemical, and chemical machining processes.

(h) Write any four applications of EBM.

EBM is used in drilling micro holes, machining hard materials, welding aerospace components, and producing precision electronic parts.

(i) What are the functions of dielectric fluid used in EDM?

Dielectric fluid acts as an insulator, cools the tool and workpiece, removes debris, and helps in spark generation.

(j) How is plasma generated in PAM?

Plasma is generated by heating a gas to a very high temperature using an electric arc, which ionizes the gas.

SECTION – B (5 × 10 = 50 marks)

(Attempt any five questions)

2(a) Explain the principle and methodology of LBM. List advantages and limitations.

Principle:
Laser Beam Machining works on the principle of melting and vaporization of material by a high-energy laser beam focused on a small area.

Methodology:
A laser source produces a beam which is focused using optical lenses on the workpiece. The intense heat causes localized melting and evaporation of material.

Advantages:
LBM can machine hard materials, produces no tool wear, high precision, and non-contact operation.

Limitations:
High initial cost, low efficiency, thermal damage, and limited depth of cut.

2(b) Explain the process of AJM with applications and limitations.

Abrasive Jet Machining uses high-velocity abrasive particles carried by compressed air or gas to remove material by erosion.

Applications:
Glass cutting, deburring, engraving, cleaning surfaces, and machining brittle materials.

Limitations:
Low material removal rate, nozzle wear, limited accuracy, and not suitable for ductile materials.

2(c) Describe the working principle and elements of chemical machining.

Chemical machining removes material by controlled chemical etching.

Elements:
Etchant, maskant, workpiece, and temperature control system.

The maskant protects areas not to be machined, while the exposed surface is etched chemically.

2(d) Discuss USM process variables influencing material removal rate.

Material removal rate depends on abrasive size, tool amplitude, frequency of vibration, static load, and properties of workpiece material.

2(e) Explain ECG with neat sketch and applications.

Electro-Chemical Grinding combines ECM and grinding processes. Material removal occurs by anodic dissolution with minor grinding action.

Applications:
Machining hard alloys, deburring, and tool sharpening.

2(f) Explain ECM process with advantages and applications.

Electro-Chemical Machining removes metal by anodic dissolution using an electrolyte.

Advantages:
No tool wear, good surface finish, complex shapes possible.

Applications:
Turbine blades, dies, and aerospace components.

2(g) Short note

(i) Metallizing:
Metallizing is coating a surface with metal spray to improve corrosion resistance.

(ii) Explosive forming:
Explosive forming uses shock waves generated by explosives to shape metal sheets.

2(h) Short note

(i) Water hammer forming:
Uses pressure waves in liquid to form metal sheets.

(ii) Electro-hydraulic forming:
Uses electrical discharge in water to generate shock waves for metal forming.

SECTION – C (2 × 15 = 30 marks)

(Attempt any two questions)

3. Explain EBM with setup and working principle.

Electron Beam Machining uses a high-velocity electron beam to melt and vaporize material.

Setup:
Electron gun, vacuum chamber, focusing lens, deflection coils, and work table.

Working:
Electrons are accelerated at high speed and focused on workpiece, generating intense heat for machining.

4. Describe EDM equipment, working, applications, and advantages.

Equipment:
Power supply, tool electrode, workpiece, dielectric tank, servo system.

Working:
Electrical sparks between tool and workpiece remove material.

Applications:
Die making, mold manufacturing, aerospace components.

Advantages:
Can machine hard materials, complex shapes, and high precision.

5. Explain the following

(i) Photo-lithography:
Used in micro-fabrication where light transfers patterns onto photo-resist material.

(ii) Electro-magnetic forming:
Uses magnetic force to shape conductive metals.

(iii) Explosive welding:
Joins metals using explosive energy creating metallurgical bonding.