03
MEMB113 ENGINEERING MEMB113 ENGINEERING GRAPHICS & CAEGRAPHICS & CAE
ENGINEERING DESIGN
ENGINEERING GEOMETRY
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Contents
• Engineering design
• Engineering geometry
• How to draw?– Examples of previous exercises
Engineering Design
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Design
• Design is the process of conceiving or inventing ideas mentally and communicating those ideas to others in a form that is easily understood.
• Normally using graphical way.• Generally, design is used for two primary
purposes:– Personal expression (usually art)– Product/process development
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Category of design
DESIGNDESIGN
Product/ProcessDevelopment(Technical)
Product/ProcessDevelopment(Technical)
Personal Expression(Artistic)
Personal Expression(Artistic)
Aesthetic(Industrial design)
Aesthetic(Industrial design)
Functional(Engineering Design)
Functional(Engineering Design)
EngineeringDesign CycleEngineering
Design Cycle
ProductProduct ProcessProcess
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Engineering design
• Engineering drawing in design process
to see the problem& possible solutions
Visualise
Sketches
Geometric model
Detail drawings
3D model
to record initial ideas
created from sketchesused for analysis
to record the precise datafor production process
Visualisation is the ability to mentally picture things that do not exist
Communication - the design solution should be communicated to others without ambiguity
Documentation - permanent record of the solution
Engineering Geometry
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Overview
• Geometry provides the building blocks for the engineering design process.
• Engineering geometry is the basic geometric elements and forms used in engineering design.
• Coordinate system– cartesian coordinate system– polar coordinate system
Cartesian coordinate system Polar coordinate system
MEMB113 | MANUAL DRAWING | CHAPTER 3
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Overview
• Absolute coordinate & Relative coordinate
• Right hand rule– to determine positive direction of axis
Absolute Relative
Right hand rule
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Geometric elements
• Can be categorised as points, lines, surfaces, solids.
• Points, lines, circles and arcs are basic 2D geometric primitives.
MEMB113 | MANUAL DRAWING | CHAPTER 3
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Geometric elements
– Point - theoretical location that has neither width, height, nor depth. It describe an exact location in space. Represented as a small cross.
– Line - has length and direction, but not thickness. May be straight or curve or both.
MEMB113 | MANUAL DRAWING | CHAPTER 3
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Geometric elements
– Circle - is a single-curved-surface, all points of which are equidistant from one point, the center
MEMB113 | MANUAL DRAWING | CHAPTER 3
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Geometric elements
Major components of a circle
MEMB113 | MANUAL DRAWING | CHAPTER 3
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Tangent
• A line is tangent to a circle if it touches the circle at one and only one point.
• At exact point of tangency, a radius makes a right angle to the tangent line.
• Two curves are tangent to each other if they touch in one and only place.
Tangent point between a straight line & a circle
Tangent point between two circles (curves)
How to draw?
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
How to draw?
• All drawing consist of the combination of basic geometric elements.
• Some of the common elements:– Straight lines– Circles– Arcs– Freeform curves
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
How to draw?
• E.g. simple object as shown• Inspect the overall size of the
object – compare to the available drawing space to decide on the suitable scale
• Observe the feature• Start drawing
– Draw circle & arc first (if any)– Draw centre lines before that– Make sure of using correct pencil
or line thickness– Draw straight lines– Add in other things e.g.
dimensions, etc.• Be careful of ‘blending’ and
cleanliness of the drawing• Make your drawing sharp and
solid
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
Points to remember
• Overall shape & feature• Line quality (thickness,
consistency, etc.)• Size & scale• Dimension (if available)• Drawing quality
(cleanliness, etc.)• Projection (if any)• Other info
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Line quality – good• Good solid object line• line thickness – good use of thick & thin• construction of arc need to be improved• blending can be further improved
Drawing examples
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Line thickness not consistent• Poor blending• construction lines – too thick, need to erase• circle construction – poor• dimensioning – poor• scale not written
Drawing examples
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Object lines – too thin• Object lines & centre lines – same thickness• Dimensioning – not follow standard
Drawing examples
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Line quality – good• Good solid object line• line thickness – good use of thick & thin• construction of arc need to be improved• blending can be further improved
Drawing examples
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Object shape is wrong! •Line thickness not consistent• Poor blending• construction lines – too thick, need to erase• circle construction – poor• dimensioning – poor• scale not written
Drawing examples
MEMB113 | Dept. of Mechanical Engineering | UNITEN | 200503 ENGINEERING DESIGN | ENGINEERING GEOMETRY
• Line quality – acceptable but should be darker• blending between straight line & arc need improvement• good lettering• missing scale
Drawing examples
End of chapter [03]
References:References:- Engineering Drawing, A.W. Boundy, McGraw-Hill, Engineering Drawing, A.W. Boundy, McGraw-Hill, 20002000- Fundamentals of Graphics Communication 3rd Fundamentals of Graphics Communication 3rd Edition, Gary Bertoline & Eric Weibe, McGraw-Hill Edition, Gary Bertoline & Eric Weibe, McGraw-Hill