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Introduction to engineering drawing for mechanical engineers.
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ENGINEERING Drawing & CADENGINEERING Drawing & CAD
Introduction to Drawing
ContentsContents Overview Sketching Engineering graphics & manual drawing
Drawing tools Drawing sheets and layout Lettering Lines Scale Abbreviations
Overview Overview Engineering graphics communication involves
the use of visual material to convey technical ideas and problem solutions.
Engineering or technical drawing – one of the most widely used method.
Definition of drawing: A graphic representation of an idea, concept or an
entity which actually or potentially exists in life.
OverviewOverview Importance:
A way of communication between engineers at all stages of the design & problem solving from initial ideas, design, analysis & manufacturing.
For Visualisation, Communication and Documentation
VisualisationThe ability to
mentally picture things that do not exist in front of the
eyes.
CommunicationThe design solution
should be communicated to
others without ambiguity
Documentation Permanent record of the solution for future
reference.
OverviewOverview Types of drawing :
artistic technical Illustrations rendering
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OverviewOverview
Examples of different drawing types
A dimensioned technical/mechanical drawing 3-D computer model of the interior of an office building
SketchingSketching
SketchingSketching
3 methods of creating technical drawings Freehand, mechanical & digital
Technical sketching is the process of producing a rough preliminary drawing representing the main features of a product or structure
Normally done by freehand, generally less finished, less structured/ restricted, & take less time to produce
SketchingSketching Technical sketches
Used extensively in the first stage of design process to visualise or convey ideas
An informal tool used by everyone involved in the design & manufacture of a product
SketchingSketching Sketching tool
Paper, pencils, eraser Sketching technique e.g.
Straight line sketch Circle & arc Component (proportional sketch) Pictorial sketch
In sketching, proportionality is important. Even though it is a freehand sketch, the lines
should be relatively sharp and straight for a good quality sketch.
Mechanical
Sketched
SketchingSketching
Sketching straight line
SketchingSketching Sketching circle
Sketching circleSketching component
(proportional)
SketchingSketching Multi-view and pictorial sketches
Engineering Graphics & Manual DrawingEngineering Graphics & Manual Drawing
Engineering graphicsEngineering graphics Drawings are widely used in engineering
applications: manufacturing, design, structural, electrical, etc.
Standards and conventions To ensure everybody using the same method Commonly used:
ANSI, ASME, ISO, JIS, MS, DIN, BS What will you learn
Producing engineering drawings Interpreting engineering drawings Graphics theory, visualisation, standards, conventions, applications,etc.
Engineering graphicsEngineering graphics E.g. Anatomy of a technical drawing
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MEMB113 | MANUAL DRAWING | CHAPTER 1
Drawing layoutDrawing layout One of the important aspect in technical
drawing is the layout What is drawing layout? Example of engineering drawing with layout Paper size ‘Components’ of a layout Title block Our layout
Drawing layoutDrawing layout Drawing layout is the standard template and
components of a drawing E.g.
Drawing layoutDrawing layout Drawing sheets – paper sizes
Usually based on 'A' series Drawing sheets material -
paper, linen, plastic film Drawing sheet layout
Sheet frames or border Usually 20mm for A0 &
A1, 10mm for others Title block or title frame
Represents general information source for a drawing
Usually at bottom right-hand corner
A1
A2
A3
A4
A4
A0 : 1189x841
A1 : 841 x 594
A2 : 594 x 420
A3 : 420 X 297
A4 : 297 X 210
A5 : 210 X 148
A6 : 148 X 105
All in mm
Title BlockThe title block is normally placed in the bottom right of the drawing frame, and it should contain the following information: - the name of the company or organization - the title of the drawing - the drawing number, which is generally a unique filing identifier - the scale - the angle of projection used, either first or third, generally shown symbolically - the signature or initials of the draftsman, checker, approving officer, and issuing officer, with the respective dates -other information as required
Material or Parts ListIf the drawing contains a number of parts, or if it is an assembly drawing, a tabulated parts list is attached to the bottom right of the drawing frame, just above the title block. The parts list should give the following information: the part number the part name the quantity required material specifications the drawing number of each individual part other applicable information When the parts list is very large a separate drawing sheet may be used for the parts list alone.
Revision TableA revision table is normally located in the upper right of the drawing frame, or at the bottom on the left side of the title block. All modifications to the drawing should be documented here.
ZoningA drawing may be divided up into a grid using letters and numbers. When zoning is used it is located inside the drawing frame. Zoning allows easy references to various parts of the drawing by referencing a coordinate such as C7.
http://www.metrication.com/drafting/layout.htm
Drawing layout - componentsDrawing layout - components
Drawing layout – title blockDrawing layout – title block A title block is the form on which the actual
drawing is a section. The title block includes the border and the various sections for providing quality, administrative and technical information. The importance of the title block cannot be minimised as it includes all the information which enables the drawing to be intepreted, identified and archived.
E.g.
Our layoutOur layout
10m
m
10mm 10mm
Paper Size : A2 (594mm x 420mm)
regular paper size
drawing frame
UNIVERSTI TENAGA NASIONAL
TITLEALL DIMENSIONS IN mm
Border width : 10mm all round
NAME
150 150
30 45
10
Lettering height : 7mm
30
COURSE NO.
SID SECTION
SCALEDATE
UNLESS STATED OTHERWISE ALL DIMENSIONS IN mm
TOLERANCESLINEAR:ANGULAR
FINISH AS MACHINE
MATERIAL CAST STEEL
DRAWN BYMY FULL NAME IS VERY LONGME 000000 SEC 01ADATE: 04/07/2005
CHECKED BY
UNIVERSITI TENAGA NASIONAL
DRAWING TITLE
SCALE 1:1 DWG NO. 001 SHEET 1 OF 1
LetteringLettering
Text is an important part of a technical drawing. Not all info required on technical dwg can be communicate graphically such as dimensions.
One method of creating text is by freehand lettering. The standard style for freehand lettering is single-stroke Gothic lettering.
LetteringLettering Characteristic of good lettering
Should be neat, not sloppy Should be uniform and
consistent i.e. same height, proportion & inclination – use guidelines
Should have proper spacing of letters and words
Should not contain unnecessary frills
Should use capital letters except for standard abbreviation e.g. mm, kg
Recommended minimum height 2.5mm
Recommended height 5mm to 7mm
Underlining of lettering should be avoided
MEMB113 | MANUAL DRAWING | CHAPTER 2
LinesLines Different line types for different purposes - to ensure drawing to be
read quickly & accurately Types of lines and thickness of line Commonly used line types & thickness:
Pencil
Description Usage Example
B/2B/0.5mm
Continuous thick
Drawing outlines & visible edges
Continuous thin
Hatching, dimension & projection lines
Continuous wavy thick
Limit of partial view
Dashed thin Hidden detail
Long & short dash thin
Center lines
2H/H/0.3mm
2H/H/0.3mm
2H/H/0.3mm
B/2B/0.5mm
LinesLines
Standard line types used in technical drawing
ScaleScale What does it mean? Scale indicates the relative size of the drawing object with the real
object Scale used should always be stated on drawing – a very
important info that is usually written in the title block. 'do not scale' / 'not to scale‘ / NTS – the drawing is not drawn to a
certain scale Recommended scale
1:1 for full size for greater than full size
2:1 for twice full size 10:1 for ten times full size
for reduced size 1:2 for half full size 1:10 for tenth full size
other common scale 1:5, 1:20, 1:50, 1:100, 1:500 etc.
Actualsize
1:1
2:1 1:2
AbbreviationsAbbreviationsWord/ phrase AbbreviationsAssembly ASSYCentre line CL orChamfer CHAMCountersink CSINKCounterbore CBOREMaterial MATLMaximum MAXMinimum MINNumber NOPitch CircleDiameter PCDRadius RAD or RRequired REQD
Word/ phrase AbbreviationsCylinder CYLDiameter DIA orExternal EXTFigure FIGHexagon HEXInternal INTSpecification SPECSquare SQStandard STDMAX MATLcondition MMCVolume VOLWeight WT