CAE Exam 1

Engineering sketch

• only prinicpal dimensions shown

• no tolerances

• no drawing or revision number

• no “drawn by“ or “approved by“

detail drawing

• all dimensions shown

• tolerances shown

• formatted title block

  • drawing number

  • revision number

  • “drawn by“

  • “approved by“

  • unit system

  • scale

  • date

Drawing sizes

ANSI - third angle view

• front view is key view

• USA standard

Glass box views

• front view

• top view

• right view

visible line

thick line used to depict visible edges

construction line

very thin, temporary layout line drawn to help structure and align a sketch or projection

hidden line

represent edges that are hidden from that view

dimension line

thin, continuous lines with arrows or ticks at the ends that include a numerical value indictating the dimension of a feature

extension line

extend from the object’s edge or a central line to the dimension line, helping to define the limits of the measured part

center line

thin, dashed lines used to indictae the central exes of circular features or geometries

phantom line

thin, dashed lines that indicate the range or extent of motion of a moving feature

cutting-plane line

used to descrube where a section is cut through an object and the direction of sight

hole based system

size of hole is kept constant, shaft size is varied to get different fits

shaft based system

size of shaft is kept constant, hole size is varied

limit dimensioning

upper and lower limit shown

plus and minus dimensioning (unequal bilateral)

single base dimension with a plus and minus tolerance

plus and minus dimensioning (equal bilateral)

base dimension with a single plus/minus value

Assembly drawing

• exploded part view

• numbered parts in balloons

• bill of materials

• title block

standard part

a part whose dimensions, material, and properties are completeley specified in an international or national standard

purchased part

any part or component that is acquired in completed from from a source but not specified in an international or national standard

standard part examples

• bolts

• screws

• rivets

• pins

• washers

• sturtcural steel and aluminum

purchased part examples

• V-belts and sheaves

• chains and sprockets

• gears

• motors, compressors, hydraulic power units

do purchased parts require detail drawins or a technical specification sheet?

no detail drawing, yes technical spec sheet

do standard parts require detail drawins or a technical specification sheet?

no detail drawing, no technical spec sheet

feature control frame

straightness

flatness

circularity

cylindricity

surface roughness

component of surface texture quantified by the deviations in the direction of the normal vector of a real surface from its ideal form

average roughness

y is the vertical distance of each point from the mean line

L is the evaluation length

RMS roughness

Z(x) is the height deviation from the mean line

L is the sampling length

roughness average rating placement

skewness

means the degree of skew, and exprsses the symmerty of peaks and valleys using the average line as the center

kurtosis

central peak sharpness compared to normal distributions, helping spot outliers

lapping

An abrasive finishing process that uses loose abrasive grit suspended in a fluid slurry between the part and the lapping tool to achieve ultra-fine surface finishes and high dimensional accuracy

honing

A precision finishing operation using bonded abrasive stones to remove small amounts of material from internal cylinder bores, leaving a characteristic cross-hatched surface texture

grinding

An abrasive machining process that uses a high-speed rotating bonded abrasive wheel to remove material and produce precise dimensions and fine finishes

broaching

A machining process that pulls or pushes a multi-tooth tool across a surface, capable of cutting complex internal or external non-circular profiles (such as keyways or splines) in a single pass

reaming

A precision cutting operation that feeds a rotating multi-edge tool into an existing hole to slightly enlarge it, improve its dimensional tolerance, and enhance its surface finish

turning and boring

Turning uses a single-point tool on a lathe to remove material from the outside of a rotating cylindrical workpiece, while boring uses a single-point tool to enlarge and finish an internal hole

planing and shaping

Linear machining processes using a single-point tool; in shaping, the tool moves back and forth, whereas in planing, the workpiece provides the primary linear cutting motion

milling

A machining process that removes material by feeding a workpiece against a rotating multi-toothed cutter to create flat surfaces, slots, or complex profiles.

drilling

A machining process that uses a rotating end-cutting tool to create initial round holes in solid materials

mechanical fastener

a device that is used to mechncially join two or more components

general fasteners

keys, pins, retaining rings

threaded fasteners

bolts, screws, studs, setscrews, etc

bolt

has a head on one end and threats on the other end, paired with a nut

screws

has a head on one end and threats on the other end, and usually have longer threats than bolts, paired with a threaded hole

studs

a rod that is threaded on both ends and joins two mating parts

major diameter (thread dimension)

outer diameter of the head

minor diamater (trhead dimension)

diamater of an imaginary cylinder that touches the bottom of the grooves

pitch (thread dimension)

distance between peaks of grooves

tensile stress ara

cross-sectional area of an unthreaded rod that would have the same tensile strength as the corresponding threaded rod

how to calculate tensile stress area

minor diameter area meaning

cross-sectional area of the threaded rod that would resist transverse shear in the threaded direction

how to calculate minor diameter area

longitudinal shear area

dependent on the dimensions of both the external and mating internal threads

how to calculate longitudinal shear area

minimum length of engagement

prevent stripping of the external thread

thread die

threading dies are used to form or cut external threads on the outside of rods or bars

drill-to-tap relationship

forming and slightly countersinking a hole to a diameter somewhat smaller than the tap’s major diameter

tap drill diameter calculations

square threads

acme threads

buttress thread

Drawing Sheet Size Progression

A-size is the same as "letter-size" (8.5" x 11"). Also, standard engineering sheet sizes progress systematically (A, B, C, D, E) where each larger size doubles the area of the previous.

Glass Box Views List

The standard primary "Glass Box" views are Front, Top, Right-side, Left-side, Bottom, and Rear (or Back).

Process Tolerances Tightness Ranking (Best to Worst)

From tightest/finest tolerance capability to loosest: Lapping/Honing → Grinding → Boring/Turning → Reaming → Broaching → Milling → Drilling → Casting.

UNC and UNF Thread Profile Shape

The shape (profile) of a UNC (Unified National Coarse) and a UNF (Unified National Fine) thread are identical; only the pitch/number of threads per inch differs.

Best Process for Internal Profile

Broaching is the best process to create an internal non-circular profile (such as a keyway, spline, or specific internal polygon shape) in a single pass.

Open-Die vs Closed-Die Forging Recognition

Closed-die forging uses matched dies to enclose the workpiece and is used for complex automotive parts like connecting rods, whereas open-die forging compresses metal between flat or simple dies without fully enclosing it.

Double Dimensioning Definition & Rule

Double dimensioning occurs when a feature or overall length is redundantly dimensioned using both individual sequential increments and an overall dimension, which can lead to conflicting tolerances; it must be avoided.

Standard Methods of Specifying Tolerances

Standard methods include limit dimensioning, unilateral plus/minus tolerancing, and bilateral plus/minus tolerancing. Scale dimensioning is not a standard method of specifying tolerances.

Transition Fit Definition

A transition fit occurs when there is an overlap of tolerances, meaning a mating pair can result in either a clearance fit or an interference fit depending on the actual manufactured parts (min clearance < 0 and max clearance > 0).

Title Block vs. Drawing Requirements

Scale and units are required information on an engineering drawing, but scale is not strictly required to be inside the title block itself (unlike drawing number, company name, etc.).

Standard Part Definition

A standard part is a component whose dimensions, material, and properties are specified and regulated by a national or international standard (e.g., ISO, ANSI, SAE).

Purchased Part Documentation Requirement

A purchased part does not require a custom detail drawing, but it does require a technical specification sheet or catalog reference in the design package.

Drawing Package Ordering Convention

The correct general order for an engineering drawing package is: Detail drawings first, followed by Subassemblies, and ending with the Master Assembly (Detail → Subassemblies → Master Assembly).

GD&T Form Controls vs Orientation/Location

Flatness is classified as a form control in GD&T (along with straightness, circularity, and cylindricity), meaning it controls the geometric shape without requiring a datum reference.

Surface Roughness Parameter Calculation (R_a)

R_a (Arithmetical Mean Roughness) is calculated as the arithmetic average of the absolute values of the profile height deviations from the mean line over the evaluation length.

Peak-to-Valley Roughness Parameters (R_z)

Extreme peaks and valleys influence R_z (maximum height of the profile) much more strongly than they influence R_a, because R_a averages out extreme anomalies.

Waviness vs. Roughness Distinction

Compared with surface roughness (micro-irregularities closely spaced), waviness refers to broader surface variations occurring over generally longer spacing/wavelength along the surface.

Lathe Boring vs. Turning vs. Drilling

Boring uses a single-point cutting tool fed into an existing hole to enlarge or finish it; drilling creates a new hole; turning cuts the external diameter of a workpiece on a lathe.

Planing vs. Shaping Cutting Motion

In planing, the workpiece provides the primary linear cutting motion while the tool feeds into it; in shaping, the tool provides the primary reciprocating cutting motion while the workpiece remains stationary.

Sand Casting Components (Cope, Drag, Core, Riser)

the core is placed inside the mold to create an internal cavity, the cope is the top half of the mold, the drag is the bottom half, and the riser supplies molten metal to compensate for shrinkage.

External Thread Nominal Size Correspondence

For a standard external thread (like a bolt), the nominal size corresponds directly to its major diameter.

Unified Thread Series Pitch Comparison (UNF vs UNEF vs UNC)

For a given nominal diameter, UNC (Coarse) has the largest pitch (fewer threads per inch, wider spacing between threads), followed by UNF (Fine) and UNEF (Extra Fine).

Transverse Shear Diameter and Thread Shear Area

The minimum minor diameter is used to calculate the area resisting transverse shear in a threaded section, whereas the tensile stress area ($A_t$) uses an effective diameter between the pitch and minor diameters.

Taps vs. Dies Functions

A tap is used to cut or form internal threads (inside a hole), while a die is used to cut or form external threads (on a rod or shaft).

Hand Tap Types (Taper, Plug, Bottoming)

A taper tap starts threads easily, a plug tap is the general-purpose hand tap used for through holes, and a bottoming tap has a flat tip to cut threads close to the bottom of a blind hole.

Metric Thread Designation Meaning ($M14 \times 2.0$)

In the metric thread notation $M14 \times 2.0$, "14" is the nominal diameter in millimeters and "2.0" is the pitch (the axial distance in millimeters between adjacent thread forms), not the number of threads per millimeter.

surface texture indication

• basic surface texture

• material removal by machining required

• material removal allowance number

• material removal prohibited

• surface texture symbol (used when any specifications present)