Question 1 (10 Marks)
(a) Why Geometrical Modelling (2 marks)
-Geometric modelling is the central part of product design.
- Geometrical modeling is the process of creating a digital representation of physical objects using
mathematical techniques. It allows engineers and designers to visualize, analyze, and simulate
complex shapes. Geometrical modeling forms the foundation for Computer-Aided Design (CAD)
systems.
(b) List modelling system in cad cam (3 marks)
-Line model, surface model, volume model.
(c) Discuss the wire frame and solid modelling (5 marks)
- In wireframe modelling, objects are represented using lines and points to define their edges and
vertices. It lacks volume or surface information. It’s useful for conceptual design and visualization.
- Solid modelling represents objects as 3D volumes with surfaces and interiors. It provides accurate
geometry for analysis, simulation, and manufacturing.
Question 2 (10 Marks)
i. Briefly describe the role of engineering analysis process in the product design cycle.
(2 marks)
-Static analysis, kinematic analysis, design for assembly, design for manufacture, heat/flow analysis.
ii. Explain with an example various step in the modern design process.
(3 marks)
Problem idenfication, problem definition, geometric modelling, engineering analysis, prototype
development, manufacturing process development, manufacturing implementation.
iii Briefly explain the various categories of manufacturing activities.
(2 marks)
Design concept, design assembly, selection of materials, cost estimates, best design concept, design
for manufacturing, prototype, production.
iv. Give a schematic and explain how the application of computers helps in the overall
Improvement of the design cycle.
Question 3
i. Read and explain the following program block. Illustrate the sequence of motions.
G01 G95 X100 Z-5 F0.25 S600 T0101
G01: This G-code specifies a linear interpolation (straight-line movement).
G95: This G-code sets the feed rate in millimeters per revolution (mm/rev).
X100: Moves the tool to the X-coordinate of 100 units.
Z-5: Moves the tool to the Z-coordinate of -5 units, indicating a downward movement.
F0.25: Sets the feed rate to 0.25 mm per revolution.
S600: Sets the spindle speed to 600 revolutions per minute (RPM).
T0101: Selects tool number 1 with offset number 1.
1. The tool moves linearly to the position (X100, Z-5).
2. The feed rate is set to 0.25 mm per revolution.
3. The spindle rotates at 600 RPM.
4. Tool number 1 with offset 1 is selected for the operation.
ii. Write a program for Cycle of Several Drilling Operations with Chip-Breaking
and ChipRemoval shown in Figure 1.
% O0001 (Drilling Cycle)
G90 G54 G17 G40 G49 G80 Initialize the machine (select XY plane, cancel tool offsets, cancel
fixed cycles, and set absolute positioning).
T0101 M06 (Tool change to tool 101)
S600 M03 (Spindle on, 600 RPM)
G00 X100 Z-5 (Rapid move to initial position)
G43 H01 Z5 (Tool length compensation)
G01 Z-20 F50 (Feed down to depth -20 at 50 mm/min)
G00 Z5 (Rapid retract to clearance plane)
G81 R5 Z-20 F100 (Start drilling cycle, retract to R-plane)
G80 (Cancel canned cycle)
M05 (Spindle off)
M30 (Program end)
Question 4
a) Describe the axes of motion for 2 ½ axis, 3 axis and 5 axis machine tools?
2½ Axis Machine Tools: These machines move along the X, Y, and Z axes. The tool can move in the
XY plane and adjust its depth (Z-axis). Suitable for 2D contouring, drilling, and pocket milling.
Commonly used for simple parts with flat surfaces.
3 Axis Machine Tools: These machines move along the X, Y, and Z axes. The tool can move in all
three directions simultaneously. Suitable for complex 3D shapes, surface machining, and contouring.
Widely used in general machining and milling operations.
5 Axis Machine Tools: These machines have additional rotational axes (A and B). The tool can tilt and
rotate, allowing access to multiple angles. Suitable for intricate parts, aerospace components, and
sculpted surfaces. Enables continuous 5-axis milling and simultaneous machining.
b. The component to be machined is shown in Figure 2. It is assumed that the pocket
is through and hence only outside is to be machined as a finish cut of the pocket.
The tool to be used is a 10 mm diameter slot drill. If an end mill is to be used the
program should be modified with a hole to be drilled first before the end mill is
used. The setting is done with point A as reference (0, 0, 0) and the reference
axes are along X and Y directions. Make a complete program as shown in Figure 2.
% O0001 (Machining Program)
G90 G54 G17 G40 G49 G80 (select XY plane, cancel tool offsets, cancel fixed cycles, and set absolute
positioning).
T0101 M06 (Tool change to slot drill)
S1000 M03 (Spindle on, 1000 RPM)
G00 X25.0 Y25.0 Z2.0 (Rapid move to initial position)
G43 H01 Z5 (Tool length compensation)
G01 Z-10 F200 (Feed down to depth -10 at 200 mm/min)
G02 X60 Y40 I10 J0 F150 (Arc from current position to point B)
G01 X70 Y30 (Straight move to point C)
G01 X60 Y20 (Straight move to point D)
G02 X50 Y30 I-10 J0 (Arc back to point A)
G00 Z5 (Rapid retract to clearance plane)
M05 (Spindle off)
M30 (Program end)
%
Question 5 (20 marks)
b) Show schematically the different forms of Numerical Control, viz. open loop and
closed loop control systems.?
c) Write a complete part program using the ISO codes for the following component for the different holes
present in the component shown in Figure 2. The cutting speed to be used is 20 m/min and the feed rate is
0.02 mm/rev. Use the lower left hand corner of the part as the datum.
