CAE Exam 1 practice questions

Double Dimensioning

A stepped part dimensioned with three consecutive dimensions and an overall dimension where nominal values agree is an example of double dimensioning.

Best Dimensioning Approach

Dimension important features from a common reference surface when appropriate.

Centerline Usage

A centerline may not be used as an extension line.

Dimensional Tolerance Methods

Scale dimensioning is not a standard method of specifying a dimensional tolerance (limit, unilateral, and bilateral are standard).

Plus/Minus Tolerance Classification

The dimension 1.500 $\pm$ 0.009 is an example of bilateral plus/minus tolerancing.

RC Fit Trend

As clearance classes progress from RC2 to RC8, the fit generally becomes looser and permits greater clearance.

Force Fit Assembly Pressure

An FN4 force fit generally requires greater assembly pressure than an FN1 light drive fit.

Minimum Clearance Calculation

For a hole (1.2500–1.2514 in) and shaft (1.2478–1.2491 in), the minimum clearance is $1.2478 - 1.2514 = -0.0036$ (or using limits: Min Clearance = Min Shaft - Max Hole, wait: Min Clearance = Min Hole limit - Max Shaft limit = $1.2500 - 1.2491 = 0.0009$ in).

Maximum Clearance Calculation

For a hole (1.2500–1.2514 in) and shaft (1.2478–1.2491 in), Max Clearance = Max Hole limit - Min Shaft limit = $1.2514 - 1.2478 = 0.0036$ in.

Transition Fit Limits

A mating pair with $C_{min} < 0$ and $C_{max} > 0$ describes a transition fit.

Title Block Requirements

Drawing number is listed as required in the title block.

Scale Requirement Location

Scale is required on the drawing, but not among the items specifically required in the title block.

Assembly Drawing Specifics

A Bill of Materials (BOM) is normally expected on an assembly drawing but not on an individual detail drawing.

Numbered Balloons Purpose

On an assembly drawing, numbered balloons primarily serve to identify components corresponding to BOM item numbers.

Standard Part Definition

A part whose dimensions, material, and properties are specified by a national or international standard.

Purchased Part Documentation

A purchased part does not require a detail drawing, but does require a technical specification sheet.

Design BOM Purchased Component

For a purchased component in a design BOM, use the OEM designation.

Drawing Package Order

The correct general order for a drawing package is: Detail drawings $\rightarrow$ Subassemblies $\rightarrow$ Master assembly.

GD&T Flatness Symbol

The flat rectangular symbol representing flatness is classified as a form control.

Process Capability Selection

For a 2-in feature requiring a tolerance of $\pm 0.0008$ in, the least precise process in the table that can meet the requirement is Grinding (tightest tolerance 0.0005 in).

Milling Capability Check

A milled feature requiring $\pm 0.0015$ in cannot be produced by standard milling since milling's tightest tolerance is $\pm 0.0020$ in.

Roughness Parameter $R_a$

For the triangular profile repeating over 0.4 mm with peak heights of $\pm 2~ \mu m$, $R_a$ is $1.0~\mu m$.

Roughness Extremes ($R_z$ vs $R_a$)

Extreme peaks and valleys influence $R_z$ more strongly than they influence $R_a$.

Surface Sharpness Parameter

Kurtosis expresses the pointing/sharpness of the surface-height distribution.

Roughness Unit Conversion

$R_a = 16~ \mu in$ is approximately equivalent to an RMS roughness ($R_q$) of 17.6 $\mu in$.

Surface Texture Symbol (Circle)

A circle inside the base of the checkmark symbol means material removal by machining is required.

Surface Texture Symbol (Bar)

A horizontal bar across the checkmark symbol means material removal is prohibited.

RMS Roughness Parameter

$R_q$ is the root-mean-square (RMS) roughness parameter.

Waviness Definition

Compared with roughness, waviness refers to surface variation occurring over generally longer spacing along the surface.

Abrasive Slurry Process

Lapping is normally performed using abrasive grit suspended in a fluid or slurry.

Non-Abrasive Cutting Process

Broaching does not normally rely on abrasive particles as the cutting medium.

Cross-Hatched Bore Texture

Honing produces a characteristic cross-hatched texture in an internal cylinder bore.

Internal Diameter Enlargement on Lathe

Boring uses a single-point cutting tool fed into an existing hole to enlarge/finish its internal diameter.

Internal Noncircular Profile Process

Broaching is especially well suited to producing an internal noncircular profile like a keyway or spline in one pass.

Prismatic Rectangular Slot Process

Milling machines a rectangular slot in a prismatic block using a rotating multi-tooth cutter.

Planing Cutting Motion

In planing, the workpiece provides the primary linear cutting motion (while the tool is stationary).

Cold-Worked Steel Properties

Cold-worked steels are typically harder and stronger than comparable standard hot-rolled steels.

Automotive Connecting Rod Process

Complex automotive parts like connecting rods are commonly produced using closed-die forging.

Sand Casting Core

In sand casting, the component placed in the mold to create an internal cavity is the core.

Long Constant Cross-Section Forming

Extrusion creates long products of essentially constant cross-section by forcing a billet through a die.

Bolt Definition

A bolt has a head and external threads and is normally paired with a nut.

Nominal Size for External Thread

For a standard external thread, the nominal size corresponds to the major diameter.

Unified Thread Series Pitch Comparison

For the same nominal diameter, UNEF has the largest pitch (finer threads, smaller pitch distance, wait: UNEF is extra fine, UNF is fine, UNC is coarse. Coarse has the largest pitch distance per thread).

Thread Designation Interpretation ($\frac{3}{4}-16$ UNF)

In $\frac{3}{4}-16$ UNF-2A, the number 16 indicates 16 threads per inch.

Unified Thread Class Suffixes

In Unified inch thread classes, the suffix A denotes an external thread and B denotes an internal thread.

UNC vs UNF Tensile Area

Changing from UNC to UNF generally produces a larger tensile stress area for a fixed nominal diameter.

Transverse Shear Area Diameter

The minor diameter (minimum minor diameter) is used to calculate the area resisting transverse shear in the threaded section.

Tensile Stress Area Effective Diameter

The effective diameter used for $A_t$ lies between the pitch and minor diameters.

Thread Engagement Length $L_e$

In longitudinal thread-shear relations, $L_e$ represents the length of engaged threads between mating parts.

Taps vs Dies

A tap cuts/forms an internal thread and a die cuts/forms an external thread.

General-Purpose Hand Tap

The plug tap is identified as the general-purpose hand tap.

Bottom Blind Hole Tap

A bottoming tap is best suited to cutting threads close to the bottom of a blind hole.

Tap-Drill Estimation Formula

Using $TD = MD - 1/N$, the estimated tap-drill for a $\frac{1}{2}-20$ thread is $0.500 - 1/20 = 0.450$ in.

Metric Tap-Drill Size ($M14 \times 1.5$)

The tap drill for an $M14 \times 1.5$ metric thread is approximately 12.5 mm.

Metric Thread Pitch Meaning

In $M14 \times 2.0$, 2.0 means the thread pitch is 2.0 mm per thread cycle, not two threads per millimeter.

Thread Profile M

The M thread profile is consistent with the Unified V-thread.

Permanent Bolted Connection Preload

The lecture recommendation for preload in a permanent bolted connection is approximately $0.75 F_p$ (75% of proof load).

Preload Calculation Example

For a bolt with proof load $F_p = 24$ kN in a permanent connection, the recommended preload is $0.75 \times 24 = 18.0$ kN.

Detail Drawing vs Sketch Difference

The primary difference between a sketch and a detail drawing is the title block on the detail drawing.

Standard Drawing Sheet Sizes

A-size is the same as "letter-size" (statement d is true among the standard drawing size choices).

Multi-view Orthographic Projections

All multi-view orthographic projections do not strictly have to have three views (can have two or more as needed).

Glass Box Views

Rear (or Back) is not one of the standard primary six "Glass Box" views (Front, Right, Left, Top, Bottom, Rear).

Reaming vs Turning Tolerances

In general, tolerances for a reaming operation can be specified to a tighter range than for a turning operation.

Tighter Tolerance Range Process

Honing typically has the tighter tolerance range compared to casting, turning, or grinding.

Line Types Identification

Center lines, visible lines, and cutting-plane lines correspond to specific standard line weights and formatting identifiers in engineering drawings.

UNC vs UNF Thread Profiles

The shape (profile) of a UNC and a UNF thread are identical, only the pitch/spacing differs.

Milled Part Achievable Tolerance

The best tolerance that can be achieved for a milled 1.6 in. part is $\pm 0.0025$ in (based on standard shop capability tables).