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Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
CAD CAM LAB MANUAL
DEPARTMENT OF MECHNICAL ENGINEERING
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
CAD INTRODUCTION
Computer-aided design (CAD), also known as computer-aided design and drafting
(CADD) is the use of computer technology for the process of design and design-documentation.
Computer Aided Drafting describes the process of drafting with a computer. CADD software, or
environments, provides the user with input-tools for the purpose of streamlining design
processes; drafting, documentation, and manufacturing processes. CADD output is often in the
form of electronic files for print or machining operations. The development of CADD-based
software is in direct correlation with the processes it seeks to economize; industry-based
software (construction, manufacturing, etc.) typically uses vector-based (linear) environments
whereas graphic-based software utilizes raster-based (pixelated) environments.
CAD is an important industrial art extensively used in many applications, including
automotive, shipbuilding, and aerospace industries, industrial and architectural design,
prosthetics, and many more. CAD is also widely used to produce computer animation for special
effects in movies, advertising and technical manuals. The modern ubiquity and power of
computers means that even perfume bottles and shampoo dispensers are designed using
techniques unheard of by engineers of the 1960s. Because of its enormous economic importance,
CAD has been a major driving force for research in computational geometry, computer graphics
(both hardware and software), and discrete differential geometry
The design of geometric models for object shapes, in particular, is occasionally called
computer-aided geometric design (CAGD).
Current computer-aided design software packages range from 2D vector-based drafting
systems to 3D solid and surface modellers. Modern CAD packages can also frequently allow
rotations in three dimensions, allowing viewing of a designed object from any desired angle,
even from the inside looking out. Some CAD software is capable of dynamic mathematic
modeling, in which case it may be marketed as CADD — computer-aided design and drafting.
CAD is used in the design of tools and machinery and in the drafting and design of all
types of buildings, from small residential types (houses) to the largest commercial and industrial
structures (hospitals and factories).
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of
physical components, but it is also used throughout the engineering process from conceptual
design and layout of products, through strength and dynamic analysis of assemblies to definition
of manufacturing methods of components. It can also be used to design objects.
GEOMETRIC MODELING
A geometric modeling is defined as the complete representation of an object that includes in both
graphical and non-graphical information. In computer-aided design, geometric modeling is
concerned with the computer compatible mathematical description of the geometry of an object.
The mathematical description of the geometry of an object to be displayed and manipulated on a
graphics terminal through signal from CPU of the CAD system. The software that provides
geometric modeling capabilities must be designed for efficient use of both by the computer and
the human designer.
To use geometric modeling, the designer construct the graphical image of the object on the CRT
screen of the IGS system by inputting three types of commands to the computer. The first type of
command generates basic geometric elements such as points, lines, and circles. The second
command types is used to accomplish scaling, rotation or other transformations of these
elements. The third type of command causes the various elements to be joined into desired shape
of the object being created on the ICG system.
During this geometric modeling process the computer converts the commands into mathematical
model, stores it in the computer data files and displays it as an image on the screen. The model
can be subsequently being called from the data files for review, analysis or alteration. The most
advanced method of geometric modeling is solid modeling in three dimensions. This method
uses solid geometry shapes called primitives to construct the object.
Basically there are three types of modeling, they are
a. Wire Frame Modeling
b. Surface Modeling
c. Solid Modeling
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WIRE FRAME MODEL:-
This is the basic form of modeling; here the objects drawn will be simple but more verbose,
geometric model that can be used to represent it mathematically in the computer. It is
sometimes referred as a stick figure or an edge representation of the object. Typical CAD/CAM
system provides users with possibly three modes to input coordinates: Cartesian, Cylindrical or
Spherical. Each mode has explicit or implicit inputs. Explicit input could be absolute or
incremental coordinates. Implicit input involves user digitizes. A wire frame model consists of
points, lines, arcs, circles &curves. Early wire frame modeling techniques developed in 1960‘s
were 2-dimensional. They are not centralized &associative. Later in 1970‘s the centralized,
associative database concepts enabled modeling of 3D objects as wire frame models that can be
subject to 3-dimensional transformations.
WIRE FRAME ENTITIES
Wire frame Entities are divided into 2 types are:
a. Synthetic Entities---------- Splines & Curves
b. Analytic Entities---------- Points, lines, Circles, arcs, conics, fillet, chamfer
Applications:
1. Two-dimensional drafting.
2. Numerical control tool path generation.
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Advantages:
1. It is simple to construct model.
2. Less computer memory to store the object.
3. CPU time to retrieve, edit or update a wireframe model is less.
4. Does not require extensive training.
Disadvantages:
1 .It is ambiguous representation of real object.
2 It lack in visual coherence and information to determine the object.
3. User or terminal time needed to prepare & or input data increases with complexity of object.
4. Inability to detect interference between components.
5. No facility for automatic shading.
6. Difficult in calculating Physical properties like Mass, surface area, centre of gravity etc.,
SURFACE MODEL:-
A surface model of an object is more complete and less ambiguous representation than it wire
frame model. It is also richer in associated geometric contents, which make it more suitable for
engineering and design applications. Surface model takes one step beyond wire frame models by
providing information on surfaces connecting the object edges. Creating a surface has some
quantitative data such as point & tangents & some qualitative data like desired shape &
smoothness. Choice of surface form depends on type of application.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
Surface Entities:
Similar to wire frame entities, existing CAD / CAM systems provide designers with both
analytic and synthetic surface entities. Analytic entities include plane surface, ruled surface,
surface of revolution, and tabulated cylinder. Synthetic entities include the bicubic Hermite
spline surface, B – spline surface, rectangular and triangular Bezier patches, rectangular and
triangular Coons patches, and Gordon surface. The mathematical properties of some of these
entities are covered in this chapter for two purposes. First, it enables users to correctly choose the
proper surface entity for the proper application. For example, a ruled surface is a linear surface
and does not permit any twist while a B – spline surface is a general surface. Second users will
be in a position to better understand CAD/CAM documentation and the related modifiers to each
surface entity command available on a system. The following are descriptions of major surface
entities provided by CAD/CAM systems
Application:
1. Calculating mass properties.
2. Checking for interference between mating parts.
3. Generating cross-sectioned views.
4. Generating finite element mesh.
Advantages:
1. They are less ambiguous than wireframe model.
2. Surface model provides hidden line and surface algorithms to add realism to the displayed
geometry.
2. Surface model can be utilized in volume and mass property calculations, finite element
modeling, NC path generation, and cross section &interference detections.
3. Change in finite element mesh size produce more accurate results in FEA
Disadvantages:
1. Surface models are generally more complex and thus require more terminal and CPU time and
computer storage to create than wireframe models.
2. Surface models are sometimes awkward to create and may require unnecessary manipulations
of wireframe entities.
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3. It requires more training to create.
4. It does not provide any topological information.
SOLID MODELING:-
A solid model of an object is more complete representation than its surface model. It is
unique from the surface model in topological information it stores which potentially permits
functional automation and integration. Defining an object with the solid model is the easiest of
the available three modeling techniques. Solid model can be quickly created without having to
define individual locations as with wire frames. The completeness and unambiguity of solid
models are attributed to the information that is related database of these models stores
(Topology--It determine the relational information between objects.)
To model an object completely we need both geometry & topological information. Geometry is
visible, whereas topological information are stored in solid model database are not visible to
user. Two or more primitives can be combined to form the desire solid. Primitives are combined
by Boolean Operations.
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SOLID MODELING APPROACH
There are two basic methods used to create solid models. They are Constructive Solid
Geometry (CSG) methods, and Boundary Representation (Brep) methods. CSG uses solid primitives
(rectangular prisms, spheres, cylinders, cones, etc.) and boolean operations (unions, subtractions,
intersections) to create the solid model. Brep methods start with one or more wireframe profiles, and
create a solid model by extruding, sweeping, revolving or skinning these profiles.
The Boolean operations can also be used on the profiles themselves and the solids generated
from these profiles. Solids can also be created by combining surfaces, which often have complex
shapes, through a sewing operation. This can be used, for example, to create the body of an
aerodynamic vehicle such as an airplane, with its carefully designed wing profiles. Further details on
these two different methods can be found in Zeid [Zeid]. These two methods can often be combined
in order to create the desired parts. Each of these methods has its limitations, and parts which are
very difficult to create using just one or the other method can be created much more easily using a
combination of both methods. Thus, most commercial solid modeling systems are hybrids using both
CSG and B-rep methods.
Boundary representation models are composed of two parts: topology and geometry
(surfaces, curves and points). The main topological items are: faces, edges and vertices. A face is a
bounded portion of a surface; an edge is a bounded piece of a curve and a vertex lies at a point. Other
elements are the shell (a set of connected faces), the loop (a circuit of edges bounding a face) and
loop-edge links (also known as winged edge links or half-edges) which are used to create the edge
circuits. The edges are like the edges of a table, bounding a surface portion.
Compared to the constructive solid geometry (CSG) representation, which uses only
primitive objects and Boolean operations to combine them, boundary representation is more flexible
and has a much richer operation set. This makes boundary representation a more appropriate choice
for CAD systems. CSG was used initially by several commercial systems because it was easier to
implement. The advent of reliable commercial B-rep kernel systems like Parasolid and ACIS,
mentioned above, has led to widespread adoption of B-rep for CAD. As well as the Boolean
operations, B-rep has extrusion (or sweeping), chamfer, blending, drafting, shelling, tweaking and
other operations which make use of these.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
The Foundation of Pro/ENGINEER
What is Pro/ENGINEER?
Pro/ENGINEER is a computer graphics system for modeling various mechanical
designs and for performing related design and manufacturing operations.
The system uses a 3D solid modeling system as the core, and applies the feature-based,
Parametric modeling method. In short, Pro/ENGINEER is a feature-based, parametric
Solid modeling system with many extended design and manufacturing applications.
How is Pro/ENGINEER different from other CAD systems?
Pro/ENGINEER was the first CAD system entirely based upon feature-based design and
parametric modeling. Today most software producers have recognized the advantage of this
approach and shifted their product onto this platform. Nevertheless, the differences between a
feature-based, parametric solid modeling CAD system and a conventional CAD system include:
Pro/ENGINEER Conventional CAD Systems
Solid Model Wireframe and Solid Model
Parametric Model Fixed Model
Feature-Based Modeling Primitive-Based Modeling
Single Data Structure and Full Function-Oriented Data Structure
Associativity and Format Interpreters
Subject-Oriented Sub-Modeling Systems A Single Geometry-Based System
Manufacturing Information Texts Attached to Geometry Entities
Associated with Features
Generation of an Assembly by Generation of an Assembly by
Assembling Components Positioning Components
Ease of Use:
• Pro/ENGINEER was designed to begin where the design engineer begins with features
and design criteria, through cascading menus.
• Expert users employ "map keys" to combine frequently used commands along with
customized menus to exponentially increase their speed in use.
• Pro/ENGINEER provides the ability to sketch directly on the solid model, feature
Placement is thus simple and accurate.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
Full Associativity: Pro/ENGINEER is based on a single data structure, with the ability to
make change built into the system. Therefore, when a change is made anywhere in the
development process, it is propagated throughout the entire design-through-manufacturing
process.
Parametric, Feature-Based Modeling:
• Pro/ENGINEER's features feature contain non-geometric information, such as
Manufacturing processes and associated costs, as well as information about location and
relationships.
• This means that features do not require coordinate systems for placement, and they
"know" how they are related to the rest of the model. As a result, changes are made quickly and
always adhere to the original design intent.
Pro/ENGINEER Functionality
The basic functionality of Pro/ENGINEER is broken into four major areas:
• Part Modeling and Design
• Assembly Modeling and Design
• Design Documentation (Drawing Generation)
• General Functionality
Part Design and Modeling
Defining Geometry - Feature-Based Design
• Create sketched features including protrusions, cuts, and slots made by extruding,
revolving, or sweeping along a 2D sketched trajectory, or blending between parallel sections
• Create pick and place features, such as holes, shafts, chamfers, rounds, shells, regular
drafts, flanges, ribs, etc.
• Sketch cosmetic features
• Reference datum planes, axes, points, curves, coordinate systems, and graphs for
creating non-solid reference datum
Manipulating Geometry and Parametric Modeling
• Modify, delete, suppress, redefine, and reorder features, as well as making
Features "read-only"
• Create table-driven parts by adding dimensions to the family table
• Capture design intent by creating relations between part dimensions and
Parameters
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• Generate engineering information, including mass properties of parts, model cross
sections, and reference dimensions
• Create geometric tolerances and surface finishes on models
• Assign density, units, material properties or user-specified mass properties
to a model
• Additional functionality available through Pro/FEATURE.
Assembly Design
• Place components and subassemblies using commands like mate, align, and insert to
create full product assemblies
• Disassemble components from an assembly
• Modify assembly placement offsets
• Create and modify assembly datum planes, coordinate systems, and cross sections
• Modify part dimensions in assembly mode
• Generate engineering information, bills of materials, reference dimensions, and
assembly mass properties
• Additional functionality available through Pro/ASSEMBLY.
Design Documentation (Model Drawings)
• Create numerous types of drawing views, including general, projection, auxiliary,
detailed, exploded, partial, area cross-section, and perspective
• Perform extensive view modifications; including changing the view scale and the
boundaries of partial or detailed views, adding projection and cross-section view arrows, &
creating snapshot views
• Create drawings with multiple models, delete a model from a drawing, set and high-
light the current model of a drawing
• Use a sketch as a parametric drawing format
• Manipulate dimensions, including show, erase, switch view, flip arrows, move
dimensions, text, or attach points
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• Modify dimension values and number of digits
• Create, show, move, erase, and switch view for standard notes
• Include existing geometric tolerances in drawing notes
• Update the model geometry to incorporate design changes
• Markup drawings to indicate changes to be made
• Export a drawing IGES file
• Additional functionality available through Pro/DETAIL.
General Functionality
• Database management commands
• Layer control for placing items on a layer and displaying Layers
• Measuring commands for distance, geometric information angle, clearance, and global
interference on parts and assemblies
• Viewing capabilities to pan, zoom, spin, shade, and re-orient models and drawings.
The Function Modules of Pro/ENGINEER
The core of Pro/ENGINEER is the feature-based, parametric solid modeling system for
modeling mechanical parts.
The part model created by this system can be used to form mechanical assemblies and to
produce engineering drawings.
The model can also be used to carry out many other related analyses, simulation,
planning and manufacturing activities such as the generation of CNC tool paths and Bills of
Material. These extended functions are reflected by the following example Pro/ENGINEER
modes.
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MODULES OF PRO/E WILDFIRE:-
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PLANE DISPLAY:-
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MOUSE OPERATION:-
MODEL DISPLAY:-
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
Ken Youssefi Mechanical Engineering Dept., SJSU 6
Default Datum Planes in Pro/E
Three Standards Principal Orthographic Planes
Top
Right
Front
Ken Youssefi Mechanical Engineering Dept., SJSU 7
Creating Solids
Sketched Features - (extrusions, revolves, sweeps, blends,
..) These features require a two-dimensional drawing (cross
section) which is then manipulated into the third dimension.
Although they usually use existing geometry for references,
they do not specifically require this. These features will
involve the use of an important tool called Sketcher.
Select a datum plane to draw.
Create a 2D sketch.
Create a feature from the sketch
by extruding, revolving,
sweeping, ….
Revolve
Sweep
Blend
Extrude
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Ken Youssefi Mechanical Engineering Dept., SJSU 8
Creating Solids
Placed Features - (holes, rounds, shells, ...) These are
features that are created directly on existing solid
geometry. Examples are placing a hole on an existing
surface, or creating a round on an existing edge of a part.
Shell
Rib
Draft
Hole
Round
Chamfer
Ken Youssefi Mechanical Engineering Dept., SJSU 9
Edit Toolbar
The final group of buttons is used for editing and
modifying existing features.
Merge
Trim
Pattern
Mirror
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Ken Youssefi Mechanical Engineering Dept., SJSU 10
Implicit Constraints in Sketcher
Ken Youssefi Mechanical Engineering Dept., SJSU 11
• vertical lines
• horizontal lines
• perpendicular lines
• tangency
• equal length lines
• equal radius
• vertical alignment
Example of Implicit Constraints
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Ken Youssefi Mechanical Engineering Dept., SJSU 12
Setting Sketch Orientation
Sketch plane - the plane on which you will draw and your view is always
perpendicular to the sketch plane.
The Orientation option list in the dialog window (Top, Bottom, Left, Right)
refers to directions relative to the computer screen, as in “TOP edge of the
screen” or “BOTTOM edge of the screen” and so on. This orientation must be
combined with a chosen reference plane (which must be perpendicular to the
sketch plane) so that the desired direction of view onto the sketching plane is
obtained.
Ken Youssefi Mechanical Engineering Dept., SJSU 13
Setting Sketch Orientation - Example
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Ken Youssefi Mechanical Engineering Dept., SJSU 14
Sketcher
Ken Youssefi Mechanical Engineering Dept., SJSU 15
The Sketcher Toolbar
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Ken Youssefi Mechanical Engineering Dept., SJSU 16
Sketcher Toolbar Flyout Buttons
Ken Youssefi Mechanical Engineering Dept., SJSU 17
Weak vs. Strong Dimensions
Sketch with weak dimensions
A dimension created by Sketcher
is called ―weak‖ and is shown in
gray. Strong dimensions, on the
other hand, are those that you
create.
You can make a strong dimension in any of three ways:
1. Modify the value of a weak dimension
2. Create a dimension from scratch by identifying entities in the sketch
and placing a new dimension on the sketch
3. Select a weak dimension and promote it to strong using the RMB
pop-up menu
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Ken Youssefi Mechanical Engineering Dept., SJSU 18
Over and Under Constrained Sketch
If there is not enough information to define the drawing (it
is underconstrained), Sketcher will create the necessary
and sufficient missing dimensions.These are the weak
dimensions.
If Sketcher finds the drawing is overconstrained (too
many dimensions or constraints) it will first try to solve
the sketch by deleting one or more of the weak
dimensions (the ones it made itself earlier).
However, if Sketcher still finds the drawing
overconstrained, it will tell you what the redundant
information is (which may be dimensions or constraints),
Ken Youssefi Mechanical Engineering Dept., SJSU 19
Extrude Command in Pro/E
Extrude
The Extrude DashboardExtrude Icon
Select Placement to define the
sketch plane
Solid
Surface
Depth options
Blind depth
Thicken Sketch
Remove material (cut)
Flip direction
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Ken Youssefi Mechanical Engineering Dept., SJSU 20
Extrude Command in Pro/E
Extruded surface
Extrude Dashboard
Surface
Depth Spec options
Extrude to selected point,
curve, plane or surface
Extrude on both sides of
the sketch, equal amount.
Extrude from the sketch by
a specified value
Thicken Sketch
A Thick extruded solid
Ken Youssefi Mechanical Engineering Dept., SJSU 21
Creating an Extruded Cut
1. Select a plane to sketch on, cannot
sketch on a curved surface.
2. Sketch the curve
3. Select Remove Material button
Remove Material
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Ken Youssefi Mechanical Engineering Dept., SJSU 22
Creating an Extruded Cut
Common dashboard controls
Material removal arrow pointing to the right.
Material
Removal
Side
Material removal arrow pointing to the left.
Ken Youssefi Mechanical Engineering Dept., SJSU 23
Blind
Thru next
Thru all
Thru until
Depth options
Creating a Hole (placed feature)
Hole types
Straight
Sketched
Standard hole
counterbore
Standard hole
countersink
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Ken Youssefi Mechanical Engineering Dept., SJSU 24
Creating a Hole (placed feature)
Hole placement:
linear or radial
The Straight hole
dashboard (default)
Standard threaded hole option
Ken Youssefi Mechanical Engineering Dept., SJSU 25
Chamfer and Fillet (Round)
Round
Chamfer
Chamfer
Dashboard
Round
Dashboard
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Ken Youssefi Mechanical Engineering Dept., SJSU 26
Creating a Revolved Feature
• Sketch a 2D profile
• Revolve the sketch
around the centerline
Revolve
Extrude
• Sketch a centerline
Ken Youssefi Mechanical Engineering Dept., SJSU 27
Creating a Sweep Feature
(Protrusion)
Trajectory
Section
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Ken Youssefi Mechanical Engineering Dept., SJSU 28
Creating a Sweep Feature (Cut)
Create an entity from an edge
Pick the top surface of the table top to sketch, insert the two edges
of the table into the sketch plane for reference, erase after finished.
Sketch the sweep trajectory (guide sweep)
Trajectory
Ken Youssefi Mechanical Engineering Dept., SJSU 29
Creating a Sweep Feature (Cut)
select Insert → Sweep → Cut, and choose the Select Traj. option
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Ken Youssefi Mechanical Engineering Dept., SJSU 30
Creating a Sweep Feature (Cut)
Sketch the cut profile on the back surface f the table top
Back surface
Ken Youssefi Mechanical Engineering Dept., SJSU 31
Creating a Swept Blend Feature
Swept Blend Dashboard
Sweep type
Insert → Swept Blend
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Ken Youssefi Mechanical Engineering Dept., SJSU 32
Creating a Swept Blend Feature
option keeps each of the
feature‘s cross sections normal to the trajectory of the
feature. Each section is created normal to a vertex of the
trajectory or normal to a datum point on the trajectory. It
requires the definition of a trajectory and the definition of
one or more sections
option keeps the feature‘s
cross sections normal to a selected planar pivot plane, edge,
curve, or axis. Each section of the feature is created normal
to the selected pivot plane. It requires the definition of a
trajectory a normal plane and the definition of one or more
sections.
Constant Normal Direction
option keeps the feature‘s cross
sections normal to a second trajectory. Each section of the
feature is created perpendicular to the normal trajectory. The
option requires the definition of a sweep trajectory, a normal
trajectory, and two or more sections.
The Normal to Projection
The Normal to Trajectory
Ken Youssefi Mechanical Engineering Dept., SJSU 33
Creating a Swept Blend Feature - Examples
The Normal to
Projection
The Normal to Trajectory
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Ken Youssefi Mechanical Engineering Dept., SJSU 34
Creating a Swept Blend Feature - Examples
Sketch the
trajectory
12
3
4
5
Ken Youssefi Mechanical Engineering Dept., SJSU 35
Creating a Swept Blend Feature - Examples
Select Insert → Swept Blend Swept Blend dashboard
Select Normal To Trajectory (default)
Select the trajectory, if there is only one sketch,
it will be selected automatically
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Ken Youssefi Mechanical Engineering Dept., SJSU 36
Swept Blend Feature - Example
Select a point and sketch the cross section
12
34
5
Ken Youssefi Mechanical Engineering Dept., SJSU 37
Select Insert when
finished with the
sketch
Follow the same steps to draw the other
sections
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Ken Youssefi Mechanical Engineering Dept., SJSU 38
Creating a Variable-Section Swept FeatureUsed to create complex geometric shapes. The option sweeps a section
along one or more trajectories.
Ken Youssefi Mechanical Engineering Dept., SJSU 39
Creating a Datum Plane Tangent to a Curve at a Point
Select the curved plane
and the Tangent option
A
Select Datum Plane
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Ken Youssefi Mechanical Engineering Dept., SJSU 40
Creating a Datum Plane Tangent to a Curve at a Point
Select the end point of the
line, the datum plane is
tangent to the cylinder at
point A.
Ken Youssefi Mechanical Engineering Dept., SJSU 41
Sketch on the created
datum plane
Extrude and cut
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ASSEMBLY DESIGN
Ken Youssefi Mechanical Engineering Dept., SJSU 3
Top-Down Design (Modeling)
The assembly file is created first and then the components
are created in the assembly file. The parts are build relative
to other components. Useful in new designs
In practice, the combination of Top-Down and Bottom-Up
approaches is used. As you often use existing parts and
create new parts in order to meet your design needs.
Ken Youssefi Mechanical Engineering Dept., SJSU 2
Bottom-Up Design (Modeling)
The components (parts) are created first and then added to the
assembly file. This technique is particularly useful when parts
already exist from previous designs and are being re-used.
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Ken Youssefi Mechanical Engineering Dept., SJSU 5
Degrees of Freedom
An object in space has six degrees of freedom.
• Translation – movement along X, Y, and Z axis (three degrees of freedom)
• Rotation – rotate about X, Y, and Z axis
(three degrees of freedom)
Ken Youssefi Mechanical Engineering Dept., SJSU 10
Fundamentals of assembly in Pro/E
In pull down menu File, select new and then choose
Assembly option.
Select
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Ken Youssefi Mechanical Engineering Dept., SJSU 11
Adding Components
Or pick the Add
Component button
in the right toolbar.
Browse and open
the file for the first
component.
In the pull-down
menu, select
Insert >
Component >
Assemble
Ken Youssefi Mechanical Engineering Dept., SJSU 12
Mating ComponentsChoose constraint type
Choose Offset typeYou may Delete or Disable any
constraint by right clicking the
constraint
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Ken Youssefi Mechanical Engineering Dept., SJSU 13
Informs you if the
assembly is fully or
partially constrained
Select Move to check the
relative motion of the
components (translation or
rotational motion)
Add new constraint
Ken Youssefi Mechanical Engineering Dept., SJSU 6
Assembly ConstraintsIn order to completely define the position of one part relative
to another, we must constrain all of the degrees of freedom.
Mate, Align, and Insert
Mate Offset
Two surfaces are made parallel with
a specified offset distance.
Mate
Two selected surfaces become
co-planar and face in opposite
directions. This constrains 3
degrees of freedom (two
rotations and one translation)
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Ken Youssefi Mechanical Engineering Dept., SJSU 7
Assembly Constraints
Align Coincident
Two selected surfaces become co-planar
and face in the same direction. Can also
be applied to revolved surfaces. This
constrains 3 degrees of freedom (two
rotations and one translation).
When Align is used on revolved
surfaces, they become coaxial
(axes through the centers align).
Ken Youssefi Mechanical Engineering Dept., SJSU 8
Assembly Constraints
Align Offset
This can be applied to planar surfaces
only, surfaces are made parallel with a
specified offset distance.
Align Orient
Two planar surfaces are made parallel,
not necessarily co-planar, and face the
same direction (similar to Align Offset
except without the specified distance).
Constrains two degrees of freedom (two rotations)
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Ken Youssefi Mechanical Engineering Dept., SJSU 9
Insert
This constrain can only be applied to
two revolved surfaces in order to make
them coaxial (coincident).
Assembly Constraints
Used with cylindrical surfaces
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EXAMPLE ASSEMBLY DESIGN
Ken Youssefi Mechanical Engineering Dept., SJSU 14
Creating an Assembly
Part Part
Assembly
Ken Youssefi Mechanical Engineering Dept., SJSU 15
Creating an Assembly Example
The example assembly requires three mates to fully define it.
First constrain: Mate between the hollow faces as shown.
This removes
three degrees of
freedom.
Hollow faces
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Ken Youssefi Mechanical Engineering Dept., SJSU 16
ExampleSecond Constrain: Align the right faces of both components.
Third Constrain: Align the top faces of both components.
top facesThe assembly is
fully defined
Right side faces One degree of
freedom left
EXAMPLE: 2
Ken Youssefi Mechanical Engineering Dept., SJSU 21
Example
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Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
COMPUTER AIDED MANUFACTURING
Programmable automation in which the mechanical actions of a ‗machine tool‘ are controlled by
a program containing coded alphanumeric data that represents relative positions between a work
head (e.g., cutting tool) and a work part
Motion Control Systems
Point-to-Point systems
Also called position systems
System moves to a location and performs an
operation at that location (e.g., drilling)
Also applicable in robotics
Continuous path systems
Also called contouring systems in machining
System performs an operation during
movement (e.g., milling and turning)
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COMPUTER NUMERICAL CONTROL MACHINE
Storage of more than one part program
Various forms of program input
Program editing at the machine tool
Fixed cycles and programming subroutines
Interpolation
Acceleration and deceleration computations
Communications interface
Diagnostics
Machine Control Unit
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Cost-Benefits of NC
Costs
High investment cost
High maintenance effort
Need for skilled programmers
High utilization required
Benefits
Cycle time reduction
Nonproductive time reduction
Greater accuracy and repeatability
Lower scrap rates
Reduced parts inventory and floor space
Operator skill-level reduced
NC PART PROGRAMMING
Manual part programming
Manual data input
Computer-assisted part programming
Part programming using CAD/CAM
MANUAL PART PROGRAMMING
Binary Coded Decimal System
Each of the ten digits in decimal system (0-9) is coded with four-digit binary number
The binary numbers are added to give the value
BCD is compatible with 8 bits across tape format, the original storage medium for NC
part programs
Eight bits can also be used for letters and symbols
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The RS274-D is a word address format
Each line of program == 1 block
Each block is composed of several instructions, or (words)
Sequence and format of words:
N3 G2 X+1.4 Y+1.4 Z+1.4 I1.4 J1.4 K1.4 F3.2 S4 T4 M2
sequence no
preparatory function
destination coordinates dist to center of circle
feed rate spindle speed
tool
miscellaneous function
COMPUTER ASSISTED PART PROGRAMMING
Write machine instructions using natural language type statements
Statements translated into machine code of the MCU
APT (Automatically Programmed Tool) Language
Part is composed of basic geometric elements and mathematically defined surfaces
Examples of statements:
P4 = POINT/35,90,0
L1 = LINE/P1,P2
C1 = CIRCLE/CENTER,P8,RADIUS,30
Tool path is sequence of points or connected line and arc segments
Point-to-Point command: GOTO/P4
Continuous path command: GOLFT/L1,TANTO,C1
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Automatic Part Programming
Software programs can automatic generation of CNC data
Make 3D model
Define Tool
CNC data
Simulate
cutting
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CNC – Lathe
List of G – codes
G00 – Rapid Traverse
G01 – Linear interpolation
G02 – Circular interpolation – clockwise
G03 – Circular interpolation – counter clockwise
G21 – Dimensions are in mm
G28 – Home position
G40 – Compensation Cancel
G50 – Spindle speed clamp
G70 – Finishing cycle
G71 – Multiple turning cycle
G75 – Multiple grooving cycle
G76 – Multiple threading cycle
G90 – Box turning cycle
G98 – Feed in mm/min
List of M-codes
M03 – Spindle ON in clockwise direction
M05 – Spindle stop
M06 – Tool change
M10 – Chuck open
M11 – Chuck close
M30 – Program stop and rewind
M38 – Door open
M39 – Door close
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CNC – MILLING
List of G – codes
G00 – Rapid Traverse
G01 – Linear interpolation
G02 – Circular interpolation – clockwise
G03 – Circular interpolation – counter clockwise
G21 – Dimensions are in mm
G28 – Home position
G40 – Compensation Cancel
G50 – Spindle speed clamp
G83 – Peck drilling cycle
G90 – Absolute coordinate system
G91 – Incremental coordinate system
G94 – Feed in mm/min
G170, G171 – Circular Pocketing
G172, G173 – Rectangular Pocketing
List of M-codes
M03 – Spindle ON in clockwise direction
M05 – Spindle stop
M06 – Tool change
M10 – Chuck open
M11 – Chuck close
M30 – Program stop and rewind
M38 – Door open
M39 – Door close
M70 – Mirroring ON in X-axis
M71 - Mirroring ON in Y-axis
M80 – Mirroring OFF in X-axis
M81 – Mirroring OFF in Y-axis
M98 – Sub program call statement
M99 – Sub program terminate
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FACING AND TURNING
EXPT. NO :
DATE :
AIM:
To machine a given work piece for given dimension using turning and facing operations.
PROGRAM:
[BILLET X32 Z70
G21 G98
G28 U0 W0
M06 T3
M03 S1500
G00 X28 Z1
G94 X0 Z-0.5 F80
Z-1
Z-2
G00 X32 Z1
G90 X28 Z-50 F100
X27.5
X27
X26.5
X2
X25
G28 U0 W0
M05
M30
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FACING AND TURNING
All dimensions are in mm
Material - Aluminum
RESULT:
Thus the given work piece was machined for the required dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
STEP TURNING
EXPT. NO:
DATE :
AIM:
To machine a given work piece for given dimension using step turning operations.
PROGRAM:
[BILLET X28 Z75
N10 G21 G98
N20 G28 U0 W0
N30 M06 T1
N40 M03 S1500
N50 G00 Z2
N60 G00 X28
N70 G94 X-1 Z-.5 F1.2 FACING
Z-1
Z-1.5
Z-2
N80 G71 U0.5 R1 CANNED CYCLE
N90 G71 P100 Q140 U0.1 W0.1 F100
N100 G01 X20 Z0 CYCLE START
N110 G01 X20 Z-25
N120 G01 X25 Z-25
N130 G01 X25 Z-50
N140 G01 X28 Z-50 CYCLE END
N150 G28 U0 W0
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N160 M05
N170 M30
STEP TURNING
All dimensions are in mm
Material - Aluminum
RESULT:
The work piece is machined as per the dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
TAPER TURNING
EXPT. NO:
DATE :
AIM:
To machine a given work piece for given dimension using taper turning operations.
PROGRAM:
[BILLET X28 Z75
N10 G21 G98
N20 G28 U0 W0
N30 M06 T1
N40 M03 S1500
N50 G00 Z2
N60 G00 X28
N70 G94 X-1 Z-.5 F100 FACING
Z-1
Z-1.5
Z-2
N80 G71 U0.5 R1 CANNED CYCLE
N90 G71 P100 Q120 U0.1 W0.1 F100
N100 G01 X20 Z0
N110 G01 X20 Z-25
N120 G01 X28 Z-50
N130 G28 U0 W0
N140 M05
N150 M30
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TAPER TURNING
All dimensions are in mm
Material - Aluminum
RESULT:
The work piece is machined as per the dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
THREAD CUTTING OPERATION
EXPT. NO:
DATE
AIM:
To machine a given work piece for given dimension using step turning operation
PROGRAM:
[BILLET X28 Z75
N10 G21 G98
N20 G28 U0 W0
N30 M06 T01
N40 M03 S1200
N50 G00 X28 Z2
N60 G71 U.5 R1
N70 G71 P80 Q130 U.1 W.1 F50
N80 G00 X15 Z0
N90 G01 X15 Z-15
N120 G01 X25 Z-30
N130 G01 X28 Z-30
N140 G01 F30
N150 S1500
N160 G70 P1 Q2
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N170 G28 U0 W0
N180 M06 T03
N190 M03 S600
N200 G00 X15.5 Z2
N210 G76 P021560 Q050 R.02
N220 G76 X13.774 Z-13 P613 Q100 F1
N230 G28 U0 W0
N240 M05
N250 M3
THREAD CUTTING OPERATIONS
All dimensions are in mm Material - Aluminum
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RESULT
Thus the work piece is machined as per the dimensions
CONTOUR MILLING
EXPT. NO:
DATE :
AIM:
To machine a given work piece for the given dimension using contour milling
PROGRAM:
[BILLET X100 Y100 Z10
[EDGE MOVE X-50 Y-50
[TOOL DEF T1 D6
G21 G94
G91 G28 Z0
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G28 X0 Y0
M06 T01
M03 S1500
G90 G00 X-25 Y-25 Z5
G01 Z-1 F30
G01 X25 Y-25
G01 X25 Y15
G03 X15 Y25 R10
G01 X-15 Y25
G02 X-25 Y15 R10
G01 X-25 Y-25
G00 Z5
G91 G28 Z0
G28 X0 Y0
M05
M30
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CONTOUR MILLING
All dimensions are in mm
Material - Aluminum
RESULT:
Thus the work piece is machined as per the dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
MIRRORING
EXPT. NO:
DATE :
AIM:
To machine a given work piece for given dimension using mirroring operations.
PROGRAM:
[BILLET X Z0
[EDGE MOVE X-50 Y-50
[TOOL DEF T1 D6
G21 G94
G91 G28 Z0
G28 X0 Y0
M06 T01
M03 S1500
G90 G00 X10 Y40 Z5
M98 P001 6789
M70
M98 P001 6789
M80
M71
M98 P001 6789
M81
M70
M71
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M98 P001 6789
M80
M81
G91 G28 Z0
G28 X0 Y0
M05
M30
O 6789
G90 G00 X10 Y40
G01 Z-1 F40
G01 X40 Y10
G01 X10 Y10
G01 X10 Y40
G00 Z5
X0 Y0
M99
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MIRRORING
All dimensions are in mm
Material - Aluminum
RESULT:
Thus the work piece is machined as per the dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com
DRILLING
EXPT. NO:
DATE :
AIM:
To drill the four holes in the given work piece as shown in the figure.
PROGRAM CODE:
[BILLET X100 Y100 Z10
[EDGE MOVE X-50 Y-50
[TOOL DEF T2 D10
N10 G21 G94
N20 G28 X0 Y0
N30 G00 Z5
N40 M06 T01
N50 M03 S1500
N60 G83 X25 Y25 Z-6 R5 Q2 F100
X-25 Y25
X-25 Y-25
X25 Y-25
N70 G00 G80 G90 Z15
N80 M05
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N90 M30
DRILLING
All dimensions are in mm
Material - Aluminum
RESULT:
Thus the work piece is machined as per the dimensions.
Prof.S.Sathishkumar www.vidyarthiplus.com www.kssathishkumar.blogspot.com