About this previous year paper
SECTION A – Short Answers (2 × 10 = 20 Marks)
(a) Characteristics of Fixed Automation High initial investment and production rate.
Product design fixed; inflexible to changes. Used for mass production (e.g., automotive assembly lines). Sequence of operations is rigidly fixed by equipment configuration.
(b) Analytic vs Synthetic Surfaces
| Parameter | Analytic Surfaces | Synthetic Surfaces |
|---|---|---|
| Definition | Defined by mathematical equations (e.g., plane, sphere) | Formed by combining or approximating points/splines |
| Example | Cylindrical, conical, spherical | Bézier, B-spline, Coons patches |
(c) Surface of Revolution
A surface created by rotating a curve (generatrix) around an axis in 3D space.
Example: rotating a semicircle about its diameter → sphere.
(d) Tabulated Cylinder
A surface generated by moving a straight line (generator) along a directrix curve while maintaining parallelism to a fixed direction.
Example: Cylindrical cam surface.
(e) Difference between G01 and G02
| Code | Function | Motion Type |
|---|---|---|
| G01 | Linear interpolation | Straight line |
| G02 | Circular interpolation (CW) | Arc or circle path |
(f) Purpose of MACRO Statement
Used to define a set of instructions under a single name.
Simplifies repetitive CNC programs by reusing code blocks.
Example:
O1000 M98 P2000 L3 ; Call macro 3 times
(g) Quadric Surfaces
Second-degree algebraic surfaces represented by:
Ax2+By2+Cz2+Dxy+Eyz+Fxz+Gx+Hy+Iz+J=0Ax^2 + By^2 + Cz^2 + Dxy + Eyz + Fxz + Gx + Hy + Iz + J = 0Ax2+By2+Cz2+Dxy+Eyz+Fxz+Gx+Hy+Iz+J=0
Examples: sphere, ellipsoid, paraboloid, hyperboloid.
(h) Manipulator
The mechanical arm of a robot designed to move, position, and orient objects.
Includes links (rigid members) and joints (rotary/prismatic).
(i) Slicing
In additive manufacturing, slicing divides a 3D CAD model into thin horizontal layers for layer-by-layer fabrication (e.g., in 3D printing).
(j) Teach Pendant
A handheld device used to manually control and program robot motion.
Functions: move robot joints, record positions, set speed & operations.
SECTION B – Descriptive Questions (Any 3 × 10 = 30 Marks)
(a) Automation Migration Strategy
A stepwise approach for gradual automation adoption:
Manual production → low investment. Semi-automatic → use programmable machines.
Fully automated → integrate material handling, sensors, control.
Ensures risk reduction & smooth technological transition.
(b) Polygon Translation Example Given: A(2,5), B(7,10), C(10,2)
Translate by (3,4):
A′(5,9), B′(10,14), C′(13,6)A'(5,9),\ B'(10,14),\ C'(13,6)A′(5,9), B′(10,14), C′(13,6)
(c) Classification & Coding in Group Technology (GT)
Classification Systems: Opitz Code – parts coded by geometry, manufacturing, material.
MICLASS, DCLASS, etc.
Advantages: Reduced setup time, design reuse, simplified scheduling.
(d) SCARA vs Other Robot Configurations
| Feature | SCARA | Cartesian | Cylindrical | Articulated |
|---|---|---|---|---|
| Motion | Selective Compliance in X–Y, rigid in Z | Linear | Rotational + Linear | Fully rotational |
| Best for | Assembly, pick & place | CNC machining | Welding | Painting |
| Axes | 4 | 3 | 3 | 5–6 |
(e) Variant Type of CAPP
Based on Group Technology coding. Uses existing process plans for similar part families.
Improves consistency and reduces planning time. Uses retrieval and modification of standard plans.
SECTION C – Long Answers (Any 1 from each pair)
3(a) Levels of Automation Device Level: Sensors, actuators.
Machine Level: CNC, PLC. Cell/System Level: FMS, AGV.
Factory Level: CIM, ERP systems. Enterprise Level: Integration of production and business.
3(b) Advantages & Disadvantages of CIM
Advantages: Paperless manufacturing, improved accuracy.
Real-time production control. Integration of CAD/CAM/CAE/ERP.
Disadvantages:
High cost, complex implementation, training needs.
4(a) Surface Modelling Terms
Blobby Objects: Soft objects defined by implicit equations that merge smoothly (e.g., molecular models).
Half Spaces: Define 3D solids by inequalities; used in solid modelling (e.g., plane divides space into two half-spaces).
4(b) DDA vs Bresenham’s Algorithm
| Feature | DDA | Bresenham |
|---|---|---|
| Type | Incremental | Integer-based |
| Accuracy | May have rounding errors | Pixel-perfect |
| Speed | Slower | Faster |
| Hardware | Software-based | Hardware-suitable |
5(a) CNC vs DNC System
| Feature | CNC | DNC |
|---|---|---|
| Control | Single machine | Multiple CNCs via central computer |
| Storage | Local | Centralized |
| Data flow | One-way | Two-way |
| Example | Machining center | Networked production cell |
5(b) Interpolation & Programming
Linear Interpolation: G01 – straight-line motion. Circular Interpolation: G02 (CW), G03 (CCW).
Absolute Programming (G90): Coordinates from origin.
Incremental (G91): Coordinates relative to last point.
6(a) Role of GT & JIT in FMS
Group Technology (GT): Organizes parts into families; enables standardization.
JIT (Just-in-Time): Reduces inventory, improves flow.
Together, they enhance efficiency and flexibility in Flexible Manufacturing Systems.
6(b) Robot Programming Methods Lead-through programming
Teach pendant programming Offline programming (simulation)
Automatic programming (sensor-based)
7(a) Automated Storage & Retrieval System (AS/RS)**
Computer-controlled system for storing/retrieving materials.
Components: Storage racks, conveyors, cranes, sensors, control computer.
Advantages: Reduced labor, accurate inventory tracking, efficient space use.
7(b) Fused Deposition Modelling (FDM)**
Process: Thermoplastic filament is heated and extruded layer by layer.
Materials: ABS, PLA, nylon. Advantages: Low cost, simple, minimal waste.
Applications: Prototyping, tooling, biomedical devices.