Engr 1513 Final Ppt

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Why Engineering Graphics? The most effective means of communicating technical ideas and problem solutions.

Engineering graphics is a language with clear precise rules that must be mastered if you are to be successful in Engineering design

Up to 92% of the design process is graphically based (remaining 8% divided between mathematics and written/verbal communication)

Why Learn Sketching? Communicate concepts and ideas

Applies to virtually all engineering disciplines

Sketching is used more than traditional board drafting techniques in Industry.

Teaches skills of proportion and scaling

A proper sketch can reflect the integrity and professionalism of the engineer who created it

Copyright Planchard 2010

Alphabet of lines

The lines used in drafting are referred to as the Alphabet of lines.

Line types and conventions for mechanical drawings are covered in ANSI Standard Y14.2M. There are four distinct thicknesses of lines: Very Thick, Thick, Medium and Thin.


Alphabet of lines

Every line on your drawing has a meaning. In other words, lines are symbols that mean a specific thing.

The line type determines if the line is part of the object or conveys information about the object.

Lets review the most common line types and widths used in Orthographic projection.


Alphabet of lines Visible lines / Feature lines: Visible lines (object lines) are continuous lines used to represent the visible edges and contours (features) of an object.

Since visible lines are the most important lines, they must stand out from all other secondary lines on the drawing.


Alphabet of lines Hidden lines: Hidden lines are short‐narrow dashed lines. They represent the hidden features of an object.

Hidden lines should always begin and end with a dash, except when a dash would form a continuation of a visible line.

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Alphabet of lines

Dimension lines:Dimension lines are used to show the extent and the direction of dimensions. If possible, dimension lines are aligned and grouped for uniform appearance. All dimension lines terminate with an arrowhead on mechanical engineering drawings; a slash, or a dot in architecture. The preferred ending is the arrowhead.


Alphabet of lines Extension lines: Extension lines

are used to indicate the termination of a dimension. An extension line must not touch the feature from which it extends, but should start approximately (2 ‐ 3 mm) from the feature being dimensioned and extended the same amount beyond the arrow side of the last dimension line. When extension lines cross other extension lines, dimension lines, leader lines, or object lines, they are usually not broken. When extension lines cross dimension lines close to an arrowhead, breaking the extension line is recommended for clarity.


Alphabet of lines Leader lines: A leader line is a

continuous straight line that extends at an angle from a note, a dimension, or other reference to a feature. An arrowhead touches the feature at that end of the leader. At the note end, a horizontal bar (6 mm) long terminates the leader approximately (3 mm) away from mid‐height of the note's lettering, either at the beginning or end of the first line.

Note: In SolidWorks, control the leader display from the dimension options.


Alphabet of lines

Leaders should not be bent to underline the note or dimension. Unless unavoidable, leaders should not be bent in any way except to form the horizontal terminating bar at the note end of the leader.

Leaders usually do not cross. Leaders or extension lines may cross an outline of a part or extension lines if necessary, but they usually remain continuous and unbroken at the point of intersection. When a leader is directed to a circle or a circular arc, its direction should be radial.


Alphabet of lines

Break lines: Break lines are applied to represent an imaginary cut in an

object, so the interior of the object can be viewed or fitted to the sheet. Line weight is thick (0.5 – 0.6 mm).


Alphabet of lines

Centerlines: Centerlines are thin, long and short dashes, alternately and evenly spaced, with long dashes placed at each end of the line. Centerlines are used to represent the axes of symmetrical parts of features, bolt circles, paths of motion, and pitch circles. Every circle, and some arcs, should have two centerlines that intersect at their center of the short dashes.

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Alphabet of lines Phantom lines: Phantom lines consist of medium‐thin, long and

short dashes. They are used to represent alternate positions of moving parts, adjacent positions of related parts, and repeated details. They are also used to show the cast, or the rough shape, of a part before machining. The line starts and ends with the long dash of (15 mm) with about (1.5 mm) space between the long and short dashes. Line weight is usually (0.45 mm).


Alphabet of lines Section lines: Section lines are thin, uniformly spaced lines that indicate the exposed cut surfaces of an object in a sectional view. Spacing should be approximately (3 mm) and at an angle of 45°. The section pattern is determined by the material being "cut" or sectioned. Section lines are commonly referred to as "cross‐hatching."


Alphabet of lines Section lines: The section pattern is determined by the material being "cut" or sectioned. Section lines are commonly referred to as "cross‐hatching."


Alphabet of lines

Cutting Plane lines:Cutting Plane lines show where an imaginary cut has been made through an object in order to view and understand the interior features. Line type is phantom. Arrows are located at the ends of the cutting plane line and the direction indicates the line of sight into the object.


Precedence of Line Types

Whenever lines coincide in a view, certain ones take precedence. Since the visible features of a part (object lines) are represented by thick solid lines, they take precedence over all other lines.

If a centerline and cutting plane coincides, the more important one should take precedence. Normally the cutting plane line, drawn with a thicker weight, will take precedence. The following list gives the preferred precedence of lines on your drawing:


Precedence of Line Types1. Visible / Feature (object) Lines2. Hidden (dashed) Lines3. Cutting plane Lines4. Centerlines

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Precedence of Line Types5. Break Line6. Dimension7. Extension Lines / Leader Lines8. Section Lines / Crosshatch Lines

What is Orthographic Projection?

Two dimensional representation of a three dimensional object.

System of drawings that represent different sides of an object.

Drawings are formed by projecting the edges of the object perpendicular to the desired planes of projection.

Copyright ‐ Planchard 2010

Classic Orthographic Projection An Orthographic projection represents different

sides of an object.


Classic Orthographic Projection

The SIX principle views are created by looking at the object, straight on, and in the indicated directions.

Each view is created by looking directly at the object in the indicated direction.


Classic Orthographic Projection The Glass box is a

very traditional drafting method of placing an object in an imaginary glass box to view the six principle views.

From each point on the object, imagine a ray, or projector perpendicular to the wall of the box forming the view of the object on that wall or projection plane.



Then unfold the sides of the imaginary glass box to create the orthographic projection of the object. Note: Third Angle Projection

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Note: Third Angle Projection – United States



Note: First Angle Projection – Europe and Asia



Transferring dimensions:

Why must views be arranged so that they align? To make it possible for

someone to interpret the drawing.

Third‐angle Projection

First‐angle Projection

First and Third Angle Projections

First Angle

Third Angle

Planes Normal

Inclined

Oblique


3D Visualization – Incline and Normal Faces

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What is Spatial Visualization? The ability to mentally manipulate 2D or 3D figures.

The ability to mentally translate an object drawn in 2D form to 3D

Why learn Spatial Visualization? Spatial skills are an important role in Engineering profession.

Studies have proven that improving spatial visualization skills have a positive impact on

Overall GPA and Retention rates

Higher grades in calculus courses

Increased ability and confidence in learning solids modeling software

Skills can be improved with practice

What contributes to spatial visualization development? Several studies have been conducted to determine spatial

visualization skills, consistent activities in pre‐college age students are: Playing with construction toys as a young child

Participating in classes such as shop, drafting or mechanics

Playing 3‐dimensional video games

Participating in some type of sports

Having well developed Mathmetical skills

Childhood development is the main contributor to spatial skills

Skills can be improved even beyond childhood w/ practice

Sketching, especially in the form of isometric drawing and hand‐held physical models is best at developing spatial skills

How are spatial visualization skills evaluated? Mental Cutting Tests

Purdue Spatial Visualization Rotation Tests

3‐Dimsional Cube Test

Mental Rotation Test

Differential Aptitude Test

Pictorial Views Pictorial sketch represents a 3D object on a sheet of 2D paper by orienting the object so you can see its width, height and depth in a single view

Three common methods are used in Engineering : Isometric, Oblique and Perspective

ISOMETRICS Isometric means “equal in

measure” and refers to the fact that the three receding axes are tilted at 30°. Isometric drawings are constructed with parallel, non‐converging lines which are drawn in exact proportion to render a three dimensional representation of an object. n of multiple views of an object. In order to fully and accurately represent the object, more than one view is typically required.

30° 30°

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OBLIQUE VIEWS Oblique drawings provide a

quick way to sketch an object and represent the three dimensions of height, widthand depth.

Oblique drawings have only one receding axis. This axis can be drawn at any angle, but is typically drawn at a 30° or 45°angle.

CAVALIER OBLIQUE

Comparison ofCavalier and Cabinet Obliques

CAVALIER OBLIQUE CABINET OBLIQUE

Perspective Sketch Represents the most realistic‐looking view.

Shows an object as it would appear in a photograph

Portions farther away from viewer are smaller and lines recede into the distance.

Multi View Drawings Standard Drawing is 3‐view, Front, Top and Right side

Combination of views must give all details of part in a clear, correct and concise way

Some parts require more or less details to accurately communicate the design, this includes:

One or Two View Drawing Used when one view is enough to accurately depict the part.

Often used for cylindrical or sheet metal parts

Section View Section views are used to clarify the interior of a part that can’t clearly be seen by hidden lines in a view

Section lines can often identify the type of material being used

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Detail View Depicts a portion of the part at a larger scale

Break or Broken View Provides ability to depict a large uniform item at a larger scale by removing portions using break lines.

Broken Out View Material is removed to a specified depth to expose inner details

Auxiliary View Provides the ability to depict an oblique or inclined plane with true dimensions

Constructive Solid Geometry Type of construction that combines 3D solid primitives to stitch together an unambiguous mathematical representation of a precisely enclosed solid

Solid Primitives include: Blocks

Cylinders,

Cones,

Spheres,

Solid Primitives are stitched together using Boolean Operations

Also known as the machinist’s Approach because the method is parallel to a machine shop Example of Standard Boolean Operations

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Dimensions

Dimensions are used to describe the shape of the part or assembly shown in a drawing view.

Dimensions in a SolidWorks drawing are associated with the model, and changes in the model are reflected in the drawing.


Dimension ‐ Types There are two main types of dimensions:

Model dimensions: dimensions created as you create each part feature. You then insert those dimensions into the various drawing views.

Reference dimensions: can be added in a drawing document (driven dimensions). You can’t edit the value of reference dimensions to change the model.


Part Dimensioning ‐ Systems There are basically three types of dimensioning systems used in creating parts and drawings: U.S. ‐ ANSI standard for U.S. dimensioning use the decimal inch value. When the decimal inch system is used, a zero is not used to the left of the decimal point for values less than one inch, and trailing zeros are used.

The U.S. unit system is also known as the Inch, Pound, Second (IPS) unit system.

Leading zeros, trailing zeros, and number of zeros to the right of the decimal point are important in dimension and tolerance display.


Part Dimensioning ‐ Systems There are basically three types of dimensioning systems use in creating parts and drawings: Metric ‐ ASME standards for the use of metric dimensioning required all the dimensions to be expressed in millimeters (mm). The (mm) is not needed on each dimension, but it is used when a dimension is used in a notation. No trailing zeros should be used.

The Metric or International System of Units (S.I.) unit system in drafting is also known as the Millimeter, Gram Second (MMGS) unit system.


Part Dimensioning – Systems

There are basically three types of dimensioning systems use in creating parts and drawings: Dual Dimensioning ‐ Working drawings are usually drawn with all U.S. or all metric dimensions. Sometimes the object manufactured requires using both the U.S. and metric measuring system. In this illustration, the secondary units (mm) are displayed in parenthesis. The Primary units are inches.


Part Dimensioning ‐ Goal

There are different rules for the display of decimal dimensions and tolerances based on millimeter and inch units.

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Part Dimensioning ‐ Goal

What is our goal when dimensioning a part? Dimensions should be given in a clear and concise mannerand should include everything needed to manufacture and inspect the part exactly as intended by the designer.

Add Reference dimensions if needed Add Notes (Local and Global) if needed Do NOT over dimension the view!

Each feature is dimensioned once, and only once

Dimensions should be placed in the most descriptive view of the feature being dimensioned.

Dimensions should be located outside the boundaries of an object whenever possible

Do not cross dimension lines or leaders

Should be aligned and grouped whenever possible


Part Dimensioning ‐ General Dimensions of size

How big is it?

Height, Width, Depth, diameter, etc.

Dimensions for location Where is it in space?

(X,Y,Z)


Part Dimensioning ‐ Cylinder

Cylindrical part in the Horizontal Position – Rectangular view


Part Dimensioning – Cylinder with a Hole

Cylindrical part – Rectangular view. Holes are dimensioned by giving their diameter and location in the circular view. Remember Gaps!!!!

Hidden Lines Visible


ANSI Y14.5 Standards All features must be dimensioned

All dimensions must have a tolerance

Drawings shall not be over‐dimensioned

Dimensions shall be arranged for optimum readability

Copyright 2010 ‐ Planchard

Tolerance The two most common Tolerance Standard agencies are:

American National Standards Institute (ANSI) / (ASME)

International Standards Organization (ISO). We will only cover the ANSI (US) standards.

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Tolerance There are two types of tolerances:

Dimensional Tolerances

Geometric and Dimensional Tolerances


Dimensional Tolerance The dimensions given on a drawing are an indication of what the limits of accuracy are.

These limits are called tolerances

Tolerances can be specified in various unit systems, but for ANSI, it is specified in English (IPS).


Dimensional Tolerance Why do we want a part’s size to be controlled by two limits?

It is impossible to manufacture parts without some variation.

The limits (Upper and Lower) are a form of quality control.


Dimensional Tolerance Choosing the tolerance for your design

Specify a tolerance with whatever degree of accuracy that is required for the design to work properly.

Choose a tolerance that is not unnecessarily accurate or excessively inaccurate.

Remember COST!


Dimensional Tolerance ‐ Types The three most common Tolerance Types are:

Limit

Bilateral / Unilateral

Plus and Minus (Title Block)


Dimensional Tolerance ‐ Types Limits are the maximum and minimum size that a part can obtain and still pass inspection.

For example, the diameter of a shaft might be specified as follows.

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Dimensional Tolerance ‐ Types The high limit is placed above the low limit. When both limits are placed on one line, the low limit precedes the high limit.


Dimensional Tolerance ‐ Types A dimension is said to have

a Unilateral (single) tolerance when the total tolerance is in one direction only, either (+) or (‐).

Meets standards of accuracy when the basic dimension varies in one directly only and is between 3" and 3.025"


Tolerance ‐ Accumulation The maximum variation between two features is equal to the sum of the tolerances placed on the controlling dimensions.


Types of Fits There are four major types of fits. Fit is the general range of tightness resulting from the application of a specific combination of allowance and tolerances in the design of mating parts. Clearance Fit

Interference Fit

Transition Fit

Line Fit


Types of Fits Clearance Fit

Always a space for the fit.

Min. Clearance > 0

Interference Fit

Never a space.

Max. Clearance 0

Lock and Key

Door and Door frame

Hinge pin

Pin in a bicycle chain


Types of Fits Transition Fit

Depending on the sizes (shaft and hole) there may be a space or not.

Max. Clearance > 0

Min. Clearance < 0

Line Fit A space or a contact (hole diameter = shaft diameter)

Max. Clearance > 0

Min. Clearance = 0

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What is GD & T It is a system of symbols, rules and definitions used to define the shape (Roundness, Flatness, Cylindricity, etc.) and design Intent (parallel, perpedicular, concentric, et.) of the model.

Objectives of GD & T Define parts based on function

Include geometric as well as size tolerances

Facilitate inspection and quality control

Reduce need for notes

Capture design intent

Dimensioning The overriding principle of dimensioning is CLARITY.

Each feature is dimensioned once, and only once

Dimensions should be selected to suit the function of the part

Dimensions should be placed in the most descriptive view of the feature being dimensioned.

Dimensions should be located outside the boundaries of an object whenever possible

Do not cross dimension lines or leaders

Should be aligned and grouped whenever possible

SPACE

EXTENSION LINE

SPACE

DIMENSION LINE

LEADER

2X R.25

1.00

2.00

Ø2.00

4.00

1.00

2.00

Ø1.00 THRU .25" (6MM) MIN BETWEEN DIMENSION LINES

.38" (10MM) MIN FROM VISIBLE LINE TO DIMENSION LINE

.03 (1MM)

.12 (3MM)6

13.50

2

11

2.5

2

5.5

ARROW MUST TOUCHEXTENSION LINE

OR

2 12 - 3W (NORMALLYEQUAL TO HEIGHTOF NUMBERS)

OR

W

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Ø.5

Ø1.00 Ø1.50Ø.50

TWO VIEW DRAWING

2.00

Ø1.50Ø.84

DIMENSIONING DIAMETERS

Ø1.13

ON END VIEW

Copyright Planchard & Planchard

SolidWorks SolidWorks is a 3D mechanical design application utilized to create:

Parts

Assemblies

Drawings

Documents are related.

Make a change to the part and the assembly and drawings also change.


SolidWorks Documents

FLASHLIGHT

LENS‐BULB

BATTERY‐PLATE

CAP‐LENS

Part

DrawingAssembly


Features Parts are made up of features.

Features add or remove material.

There are two types of features: Sketched – requires a sketched profile

Applied – requires an existing edge or face

Extruded Boss/Base is a sketched feature that adds material and requires a 2D sketch.

Fillet feature adds/removes material along a selected edge or face.


Sketched and Applied FeaturesSketch Feature Applied Feature

2D Sketch

Extruded Feature Fillet Feature


Dimensions and Parameters Dimensions determine the overall size of a part, such as length or radius.

Change a dimension value to modify the part.

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Dimensions and Parameters Features are driven by parameters that determine different characteristics of a feature, such as the number of holes in a pattern, or the depth of the hole.


Default Reference Planes Front Plane

Top Plane

Right Plane

What Plane would you sketch this L‐shaped profile on?

Geometric Relations Fundamentals Geometric Relations

Geometric restrictions that can be applied to geometric entities

Horizontal, parallel, perpendicular and tangent

Dimensional Constraints

Describe the size and location of individual geometric shapes

Added using the “Smart Dimension” command

Parametric Relations

Links are used when multiple dimensions have the same value

Equations are user‐defined mathematical relations between model dimensions.

Engr 1513 Final Ppt

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