Machine Design and Shop Practice Practice Review

Comprehensive review flashcards covering machine design, mechanical elements, strength of materials, kinematics, and shop practice formulas and terminology.

What is the radial distance in a gear measured between the addendum circle and dedendum circle, which equals the sum of the addendum and the dedendum?

Whole depth

What term describes the amount by which the width of a tooth space exceeds the thickness of the engaging tooth measured on the pitch circle?

Backlash

What is the formula and value for the polar section modulus $Z_j$ of a solid shaft having a diameter of $101.6\,mm$?

$$Z_j = \frac{\pi}{16}D^3 = \frac{\pi}{16}(10.16\,cm)^3 = 205.9\,cm^3$$

For an upright cylindrical water tank $6\,m$ in diameter and $6\,m$ high completely filled with water ($\rho = 1000\,kg/m^3$, $g = 9.8066\,m/s^2$), what is the minimum plate thickness if the allowable stress is limited to $40\,MPa$?

$$t = \frac{p D}{2 s_t} = \frac{(58.8396\,kPa)(6\,m)}{2(40\,000\,kPa)} = 0.00441\,m = 4.41\,mm$$

In limits and fits, what is the algebraic difference between the maximum limit of size and the corresponding basic size?

Upper deviation

In limits and fits, what is the algebraic difference between the minimum limit of size and the corresponding basic size?

Lower deviation

Which deviation is defined as either the upper or the lower deviation, depending on which is closer to the basic size?

Fundamental deviation

What is the total allowable variation of a dimension, defined as the difference between the maximum and minimum size limits of a part?

Tolerance

What is the formula for the Wahl factor $K_w$ of a helical compression spring in terms of its spring index $C$?

$$K_w = \frac{4C - 1}{4C - 4} + \frac{0.615}{C}$$

What is the formula for the Bergstrasser factor $K_B$ of a helical coil spring as a function of the spring index $C$?

$$K_B = \frac{4C + 2}{4C - 3}$$

What is the curve correction factor $K_c$ expressed in terms of the Wahl factor $K_w$ and the direct shear factor $K_s$?

$$K_c = \frac{K_w}{K_s} = \frac{\frac{4C - 1}{4C - 4} + \frac{0.615}{C}}{\frac{2C + 1}{2C}}$$

What term describes the capacity of a material to absorb energy when deformed elastically and release it upon unloading?

Resilience

What is the strain energy per unit volume required to stress a material from an unloaded state to the point of yielding?

Modulus of resilience

What is the ability of a material to absorb energy up to the point of fracture?

Toughness

How is the tooth thickness $t$ of a standard spur gear computed from its diametral pitch $P_d$?

$$t = \frac{1.5708}{P_d}$$

To ensure an adequate factor of safety and good proportion in shaft design, what should the key width $b$ be relative to the shaft diameter $D$?

$b \approx \frac{D}{4}$ (one-fourth of the shaft diameter)

What length of square key is required for a $4\text{-in}$ diameter shaft transmitting $1000\,Hp$ at $1000\,rpm$ if allowable shear stress is $15\,ksi$ and compressive stress is $30\,ksi$?

$L = 2.1\,\text{inches}$ (based on $T = 63\,000\,\text{in}\cdot\text{lb}$: shear gives $L = \frac{2T}{s_s b D} = 2.1\,\text{in}$, compression gives $L = \frac{4T}{s_c t D} = 2.1\,\text{in}$)

For shafts at right angles and in the same plane, what is the formula for the pitch angle $\gamma$ of a straight-tooth bevel pinion with $T_p$ teeth driving a gear with $T_g$ teeth?

$$\gamma = \tan^{-1}\left(\frac{T_p}{T_g}\right)$$

What formula calculates the lowest critical angular speed $\omega_{cr}$ in $\text{rad/s}$ for a simply supported shaft of span $L$ with a single central disc of weight $W$ (neglecting shaft weight)?

$$\omega_{cr} = \sqrt{\frac{576 E I g}{W L^3}}$$

What is the chemical composition of stainless steel 302?

$18\%$ chromium and $8\%$ nickel

What is the minimum percentage of chromium that an alloy steel must contain to be classified as a stainless steel?

At least $10\%$

What is the equivalent stiffness $k_e$ of three extension springs connected in series with individual stiffnesses $k_1 = 4\,kN/m$, $k_2 = 6\,kN/m$, and $k_3 = 6\,kN/m$?

$k_e = \frac{12}{7} \approx 1.71\,kN/m$ (since $\frac{1}{k_e} = \frac{1}{4} + \frac{1}{6} + \frac{1}{6} = \frac{7}{12}$)

What is the equivalent spring constant $k_e$ of three springs connected in parallel rated at $4\,kN/m$, $5\,kN/m$, and $6\,kN/m$?

$$k_e = 4 + 5 + 6 = 15\,kN/m$$

In a lathe machine, what term refers to the diameter of the largest workpiece that can rotate in a chuck or between centers without hitting the bed?

Swing

What general term refers to the fit between mating cylindrical parts when the internal member (hole) is larger than the external member (shaft)?

Clearance

Which lubrication regime occurs when non-conformal surfaces are completely separated by a lubricant film and no asperities are in contact?

Elastohydrodynamic lubrication

What lubrication type introduces lubricant into the load-bearing area at high pressure to separate surfaces without requiring relative motion between the parts?

Hydrostatic lubrication

What lubrication type relies on the relative motion of the surfaces to form a thick, load-carrying fluid film governed by fluid mechanics?

Hydrodynamic lubrication

What surface-hardening process heats alloy steel to approximately $900^\circ F$ to $1150^\circ F$ (or $950^\circ F$) in an ammonia gas atmosphere, followed by slow cooling?

Nitriding

What mechanical process produces residual compressive stresses on a part surface through a series of hammer blows?

Peening

Which ferrous metal has the lowest carbon content, typically containing less than $0.04\%$ carbon?

Wrought iron

What element is added in increased amounts to plain carbon steel to produce free-cutting steel (such as AISI C1112) for improved machinability?

Sulfur

What term describes a material, such as wood, that has unique and independent mechanical properties in three mutually perpendicular directions?

Orthotropic material

What non-magnetic, corrosion-resistant alloy of nickel, iron, chromium, and cobalt is precipitation-hardened to 48–50 Rockwell C and used in watch and instrument springs?

Dynavar

In CNC machining, what do the G-codes G00 and G04 represent?

G00 represents rapid traverse; G04 represents dwell or rest

In CNC programming, what do the M-code commands M03 and M06 represent?

M03 represents spindle start in a clockwise rotation; M06 represents an automatic tool change

In CNC machining, what does the acronym MDI stand for?

Manual Data Input

What is steel called when it is strongly deoxidized by deoxidizing elements so that no gas evolves during solidification and it lies quietly in molds?

Killed steel

What heat-treatment process involves heating steel above its critical range and cooling it in still air to produce a fine pearlite structure and promote uniformity?

Normalizing

To prevent dynamic instability and excessive vibration, within what percentage range of the critical speed should a rotating shaft avoid operating?

Within $\pm 20\%$ of the critical speed

What cracking failure occurs when a hot part is quenched suddenly due to high temperature gradients inducing high stress gradients?

Thermal-shock failure

What is the alternative name for the Maximum-Shear-Stress Theory of failure?

Tresca yield criterion

What is the alternative name for the Distortion-Energy Theory of failure?

von Mises criterion (or octahedral shear-stress theory)

Which cumulative fatigue damage theory states that the damage incurred at any stress level is directly proportional to the cycle ratio at that stress level?

Miner's Rule

What type of deep-groove ball bearing features inner and outer races with pronounced grooves for the rolling elements?

Conrad bearing

What type of column formula is standard for cast iron columns when the slenderness ratio $L_e / k$ does not exceed 70?

Straight line formula ($\frac{P}{A} = 9000 - 40\left(\frac{L_e}{k}\right)$)

Which type of key allows the hub to slide axially along the shaft while preventing rotation?

Feather key

What is the formula for the normal stress $s$ in a thin-walled spherical pressure vessel of diameter $D$, thickness $t$, internal pressure $p$, and joint efficiency $E_j$?

$$s = \frac{p D}{4 t E_j}$$

In a thin-walled cylindrical pressure vessel, what is the ratio between the longitudinal stress $s_L$ and the tangential (hoop) stress $s_t$?

$s_L = \frac{1}{2} s_t$ (since $s_L = \frac{p D}{4 t}$ and $s_t = \frac{p D}{2 t}$)

How is the size of a precision sine bar designated?

By the center-to-center distance between the rollers

In machine shop practice, what is the primary purpose of a V-block?

To support and check cylindrical (round) jobs during layout and inspection

What geometric difference distinguishes a pillar file from a standard hand file?

A pillar file is tapered in thickness and of uniform width (for filing narrow slots and keyways), whereas a hand file is thick, rectangular, and has parallel edges.

What type of pliers features an adjustable slip pivot to grip large parts and can also cut small-size wire?

Slip-joint pliers (combination pliers)

In roller chain power transmission, what empirical formula defines the maximum practical chain pitch $p_{\max}$ (in inches) for a sprocket running at $n\,rpm$?

$$p_{\max} \le \left(\frac{900}{n}\right)^{\frac{2}{3}}$$

What is the formula for the lead angle $\lambda$ of a power screw having lead $L$ and mean diameter $D_m$?

$$\lambda = \tan^{-1}\left(\frac{L}{\pi D_m}\right)$$

What formula gives the tightening torque $T$ required to set an initial tension $F_i$ on a bolt of nominal diameter $D$?

$T = C D F_i$ ($C = 0.20$ for as-received bolts, $C = 0.15$ for lubricated bolts)

How is the rating life $B_{10}$ in million revolutions ($\text{mr}$) calculated for a ball bearing operating at a given rpm and service hours?

$$B_{10} = \frac{(\text{Hours})(60\,\text{mins/hr})(\text{rpm})}{10^6}$$

What is the standard pressure angle normal to the thread for an ACME thread form?

$$14.5^\circ$$

How is the Factor of Utilization defined in relation to the Factor of Safety?

$$\text{Factor of Utilization} = \frac{1}{\text{Factor of Safety}}$$

Neglecting centrifugal effects, what formula expresses the belt tension ratio $\frac{F_1}{F_2}$ for a belt drive with coefficient of friction $f$ and wrap angle $\theta$ (radians)?

$$\frac{F_1}{F_2} = e^{f\theta}$$

What law states that the sum of the shortest and longest links cannot exceed the sum of the remaining two links for continuous relative rotation to occur in a planar four-bar linkage?

Grashof's Law

What is the trade name of the patented cobalt-chromium-tungsten nonferrous cutting alloy used for machining at elevated cutting speeds?

Stellite

What formula calculates the maximum deflection $\delta$ at the free end of a cantilever beam of length $L$ under a concentrated end load $W$?

$$\delta = \frac{W L^3}{3 E I}$$

What are the primary base alloying metals present in Inconel and Monel?

Inconel is primarily nickel ($80\%$) and chromium ($14\%$); Monel is primarily nickel and copper

What is the first stage of the engineering design process that evaluates whether a proposed project is both technologically possible and financially profitable?

Feasibility stage