Lecture #1 - Mechanical Drawing Introduction

8/3/2019 Lecture #1 - Mechanical Drawing Introduction

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ME231 Lecture Topics

Overview of prerequisite course

ISO Projections, standards, orthogonal and auxiliary projections

Screws, keys, pins, rivets and other types of connections

Sectioning

Dimensional Tolerences and ISO Fits Midterm Exams

Surface Quality

Geometric Tolerances Gears, Bearings, Steel Structures, Piping, Electrical and

Welding Symbols

General Review


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Technical Drawing Review


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Perspective projection Linear perspective

One-point perspective Two-point perspective Three-point perspective Zero-point perspective

Curvilinear perspective

Reverse perspective

Types of Projection

Parallel projection Orthographic projection

Multiviews Plan, or floor plan

Section Elevation Auxiliary

Axonometric projection (i.e. pictorials) Isometric projection Dimetric projection

Trimetric projection Oblique projection

Cavalier projection Cabinet projection


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Perspective and Parallel

Projections


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Parallel vs. Perspective Projection


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One Point Perspective Projection


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Two Point Perspective Projection


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Three Point Perspective Projection


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Dimetric and Trimetric

Parallel Projections


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Dimetric,

Trimetricand Isometric

Parallel Projections


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Oblique Projections

Drawn in arbitrary angle


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Cavalier Projection

Depth is unscaled

Usually drawn at 30

or 45


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Cabinet Projection

Depth is scaled

to (or to 2/3

wrt the angle)


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Orthographic Projection Types

First Angle Projection

Third Angle Projection


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Orthographic Projection Types


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Auxilary Projection


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Auxilary Projection


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Auxilary Projection

Removed Relations


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Technical Drawing Review

A technical drawing must be brief, clean and

aesthetic, providing only the necessary and

sufficient information.Redundant information shall not be allowed

(such like repeating dimensions)

Only required number of projections shall beincluded (or as much as sufficient)

Steel plates may be defined by thickness=..mm

Symmetrical parts may be defined with one half only

Shafts may be shortened or defined by multi-sections

Bolts & Nuts and similar standard machine parts maybe symbolically identified, etc


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Standard Line Types, Scales and

Representations must be used.Standard Scales :

50 20 10 5 2 1 1/2 1/5 1/10

1/20 1/50 1/100

1/200 1/500 1/1000

1/2,000 1/5,000 1/10,000

Projection types must be paid high attention

(ISO-A = 3rdAngle / ISO-E = 1stAngle)


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Linetypes and Lineweights

0.5 mm

0.2 mm

0.35 mm

0.2 mm

0.2 mm

0.5 mm

0.5 mm

0.2 mm


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L

inetyp

esan

dLine

weigh

ts

Det

ailed


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L

inetypesw

ithEx

amples


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Dimensioning Includes :

Dimensions (Linear, Aligned, Radial, Angular, etc.)

Tolerances (Perpendicularity, Flatness, Concentricity, etc.)

Surface Quality Symbols (Surface Tolerancing,Welding, Hardening, etc.)

Done For :1) Manufacturing (CNC or worker terminology)

2) Functioning (Assembly & Mechanism)

3) Control (Quality Control)

Dimensioning must be done very clean and perceptible,allowing no confusion over values, references and mainbody of drawing.


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Reminders :

A dimension is never written upside down

All co-oriented dimensions must face same side

Line Types must be strictly utilized !

Dim lines shall preferably do not intersect eachother, or the dim values, or the drawing itself

When axis of symmetry is used, the symmetric

dimensions are not repeated


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Basic Dimensioning Errors


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Reminders


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Examples of Mechanical Drawing


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How many views are necessary?


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Answer 1 ?


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Answer 2 ?

Thickness = 0.500

Advices on Technical Drawing


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Advices on Technical Drawing

1.All CAPS!2.All Decimals3.Select a front view that best describes the part4.Remove hidden lines unless absolutely necessary to describe the shape of the object5.Consider datumsand dimensioning scheme based on

1.Feature relationship

2.Manufacturability and inspection3.Reduce math for machinist

6.Do not duplicate dimensions, use reference dims if necessary to duplicate7.Do not dimension to hidden lines8.Place dims between views if possible

9.No dims on body of part. Offset .38inch from object outline10.Place all dims for same feature in one view if possible11.Dim lines cannot cross dim lines12.Dim lines should not cross extension lines13.Extension lines can cross extension lines14.Use center marks in view(s) only where feature is dimensioned15.Use centerlines and center marks in views only if feature is being dimensioned or

referenced otherwise omit.16.When multiples of the same feature exists in a view, dimension only one of the features

and lablethe dim as NumberXDIM meaning that the feature exists in thatviewNumbertimes. For example, 4X .250implies that in the view, there exists 4 likedimensions for the dimensioned feature

17.Minimize use of centerlines between holes etc, they add little value and clutter theobject being drawn.


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Calipers (Kumpaslar)

Mi (Mik l )


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Micrometers (Mikrometreler)

M f i Hi


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Manufacturing History

~1850 - Interchangable Parts- Drawing Conventions / Tolerances / Modern

Machine Development

~1900 - Standardized Work (Working Cond.,Tools, Equip,Technical Proceedings, Administrative Proceedings, Workplace, Motion Sequencing,Materials, Quality Reqs)

- Time Study

- Worker / Management Dichotomy

- Process Charts

- Motion Study

~1917 - Assembly Lines- Flow Lines (Async, Sync, Cont.)

- Manufacturing Strategy

M f t i Hi t


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~1945 - SPC (Statistical Process Control)- TQM (Total Quality Management)

~1950 - 1990- Just-In-Time System

- TPS (Toyota Production System)- Stockless Production

- World Class Manufacturing

~1995 - Lean Manufacturing

M f t i Hi t


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The 7 Wastes (TIMWOOD)

1. Transportation2. Inventory

3. Motion

4. Waiting *5. Over-processing *

6. Over-production

7. Defects *


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Solid Modelling Major Types of Modelling

Customer Modelling Requirement Modelling

Analytic Modelling

Geometric Modelling

Functional Modelling

ProductModel


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Parametric Solid Modeling (PSM) Is a must for designing a new product or

improving one Done uzing expertized software like;

CATIA, UNIGRAPHICS, PROENGINEER,I-DEAS, INVENTOR, SOLIDWORKS etc.

Allows further analysis of models, as of

Thermal, Flow, Kinematic or Dynamicaspects.

Documents

Lecture #1 - Mechanical Drawing Introduction