Engineering Graphics Exam 1

MizzouEnginr1100

CAD

Computer Aided Design

CADD

Computer Aided Design & Drafting

CAM

Computer Aided Manufacturing

CIM

Computer Integrated Manufacturing

CAE

Computer Assisted Engineering

Reading Drawings

Interpreting drawings made by others

Technical Drawing

Drawings used to express technical ideas

Engineering Design Graphics

Technical Drawings representing designs & specifications for physical objects

Design Process

Stage 1- Identification of Design Problem

Stage 2- Problem Solving Concepts and Ideas

Stage 3- Compromise Solutions

Stage 4- Models or Prototypes

Stage 5- Production or working Drawing

• manufacturing

• marketing

• service

• etc.

• assembly

multiview projection

system of views for an orthographic projection

three regular views

Top, front, and right side views.

who uses the third angle projection

united states

Line Types

center, hidden, phantom, and continuous

Visible lines

• represent visible edges and boundaries.

• takes precedence over and covers up a centerline or a hidden line when they coincide in a view

• Continuous and thick (0.5 - 0.6 mm).

Hidden lines

•represent edges and boundaries that cannot be seen.

• takes precedence over a centerline

•Dashed and medium thick (0.35 - 0.45 mm).

Center lines

• Represent axes of symmetry.

• indicate a path of motion

• show the location for bolt circles and other circular patterns

• Long dash - short dash and thin (0.3 mm).

Phantom line

• Used to indicate imaginary features

✓ alternate positions of moving parts

✓ adjacent positions of related parts

• The line type is long dash - short dash - short dash and the line weight is usually thin (0.3 mm).

Break line

• Used to show imaginary breaks in objects.

• A break line is usually made up of a series of connecting arcs. • The line type is continuous and the line weight is usually thick (0.5 - 0.6 mm).

isometric view

provides an easy visual reference for the part described in the orthographic views

Fillet

rounded interior corner blend between 2 surfaces

to strengthen adjoining surfaces or allow a part to be removed by a mold

Round

A rounded exterior blend between surfaces; is used to make edges and corners easier to handle, improve the strength of castings, and allow for removal from a mold

Counterbore

A cylindrical recess around a hole, usually to receive a bolt head or nut

countersink

a cone-shaped recess around a hole often used to receive a tapered shrew head

Spotface

a shallow recess like a counterbore used to provide a good bearing surface for a fastener

boss

a short raised protrusion above the surface of a part used to provide a strong flat bearing surface

lug

a flat or rounded tab protruding from the surface usually to provide a method for attachment

Flange

a flattened collar or rim around a cylindrical part to allow for attachment

chamfer

an angled surface used on a cylinder to make it easier to start into a hole or a plate to make it easier to handle

neck

a small groove cut around the diameter of a cylinder often where it changes diameter

keyway/keyseat

a shaped depression cut along the axis of a cylinder or hub to receive a key used to attach hubs, gears, and other parts to a cylinder so they will not turn on it

knurl

a pattern on a surface provided for better gripping or more surface area for attachment often used on knobs and tool handles

bushing

hollow cylinder often used as a sleeve, guide, or bearing

Fillets and Rounds

• Sharp corners are usually avoided in cast or forged parts

• Difficult to produce

• Can weaken part

• 2 intersecting rough surfaces produce rough corner

• Rounded corner (unless fillet) in drawing means both surfaces are rough

• 2 machined surfaces produce a sharp corner

• Sharp corner in drawing means one or both surfaces is machined

Holes

specify the diameter for anything more than 180 degrees

-Drill bits specified by diameter

Specify fillets and arcs less than 180 degrees

blind hole

specify cylinder hole only

Cylinders & Ellipses

• Circle cross-section turns into ellipse when viewed off axis.

• Cylinder cut at angle has elliptical face.

• Can reflect numbered/lettered points and fit curve to project to another view.

Cylinder Intersections

• If small cylinder intersects large one, no curve is shown. Adds little information for amount of work required.

• If larger intersection, can approximate with arc of same radius as larger cylinder.

• Large intersections can also be plotted by projecting specific points.

• Equal-diam. cylinders are shown with straight intersections.

• Prism intersections are similar.

Runouts

• Small curves shown where fillets intersect plane surfaces tangent to cylinders.

• Radius equal to fillet.

• Angle of about 1/8 of circle (~45 deg).

• Different appearances depending on intersecting surface • Flat web in e

• Rounded web in f

• If two intersecting fillets, runout direction determined by larger fillet (g & j)

• Approximations, not completely accurate

Auxiliary Views

created using a projection plane different from one of the 6 principal planes

not parallel to the standard planes of projection.

shows the true size and shape of the hole feature

Partial Auxiliary Views

common because entire view is often unnecessary and difficult to read.

should be connected by centerline or reference line to view from which it is projected. Then it does not appear lost and unrelated to other views.

Break line can be used

Half Auxiliary View

If auxiliary view symmetrical → Can draw only half view to save space and time

Detail View

Used for small features.

Partial Views

Used to show only pertinent features

Casting

A part is produced by the solidifying a material in a mold.

Mold

A form made of sand, metal, or other material. The melted material is poured or injected into the mold and allowed to solidify.

Parting line

A line on the drawing that represents the mating surfaces of the mold

Draft

The taper given to a part so that it can be extracted from the mold.

Cast and Molded Parts

➢ Fillet radius

➢ Corner radius

Surface roughness symbol

Used to indicate machined surfaces (slide24 Lecture 3 - Advanced drawing techniques & Pictorial Views)

Welding

➢ Joins metal by heating the surfaces above the melting temperature

Weld symbols

used on detailed drawings to indicate the type, location and size of the weld.

fillet weld

v groove weld

square groove weld

bevel groove weld

pictorial drawings

a pseudo 3-D drawing. → They are used to aid visualization and illustrating assembly

pictorial types

➢ Three basic types:

→ Axonometric (most common = Isometric)

→ Oblique (most common = Cabinet oblique)

→ Perspective

types of axonometric Projections

Three types

→ Isometric

→ Dimetric

→ Trimetric

Axonometric Projections

projectors are perpendicular to the projection plane and parallel to each other.

principle edges are 90 degrees apart on the physical object

Types of Oblique Projections

Three types

→ Cavalier (full scale)

→ Cabinet (half scale)

→ General (scaled not full or half)

Oblique Projections

projector NOT perpendicular to the projection plane but are parallel to each other

Perspective Projections

Three types → One-point → Two-point → Three-point

Drawing Linear Features

Step 1) Draw the three construction lines that represent the isometric axes.

Step 2) Draw a defining box. → Sides = maximum height, width and depth dimensions of the object.

Step 3) Draw the lines of the object that are parallel to the axes.

Step 4) Add the lines of the object that are not parallel to one of the axes.

Step 5) Erase or remove the construction lines. Step 6) If the drawing is produced in a 2-D drawing package, it should be scaled by 80%.