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POE Final Exam Study Guide
Career Resources
Engineering: profession in which knowledge of advanced mathematical and natural sciences gained by higher education, experience, and practice; is devoted to
creation of new technology for benefit of humanity.
Engineering Technology: profession in which knowledge of applied mathematical and natural sciences gained by higher education, experience, and practice; devoted
to application of engineering principles and implementation of technological advances for benefit of humanity. Education focuses on analyzing, applying,
implementing and improving existing technologies.
Aerospace Engineering: Design, develop, and test aircraft and spacecraft ranging from rockets and spacecraft to gliders and small passenger aircraft.
Agricultural Engineering: Create technology to advance food, biological, irrigation, and machinery systems.
Biomedical Engineering: Devise procedures and devices to improve medical conditions.
Chemical Engineering: Address issues related to chemical production, transformation of raw materials, and chemical use.
Civil Engineering: Plan the design, construction, and maintenance of various civil structures.
Computer Hardware Engineering: Research, design, develop, and test computer systems and computer-related equipment.
Electrical Engineering: Design, develop, and test the manufacture of electrical equipment and large-scale electrical systems.
Electronic Engineering: Design, develop, and test small electronic systems, such as appliances, telephones, surgical devices, etc.
Environmental Engineering: Solve environmental problems related to pollution, water use, materials and energy use, waste treatment, etc.
Health & Safety Engineering: Identify potential hazards and develop protocols to prevent or reduce hazardous situations.
Industrial Engineering: Plan most effective, efficient ways to build structures, lay out production facilities, run organizations, transport goods, etc.
Marine & Ocean Engineering: Design, construct, operate, and maintain machinery or structures that exist in or near water.
Materials Engineering: Develop, process, and test materials to be used to fulfill a specific design purpose.
Mechanical Engineering: Research, develop, design, manufacture, and maintain devices that produce or consume power.
Mining & Geological Engineering: Design, develop, and maintain mines, mining equipment, and mining techniques to locate / extract ores / minerals from the Earth.
Nuclear Engineering: Develop methods and systems that utilize nuclear materials for energy, medicine, and industry.
Petroleum Engineering: Locate oil or natural gas reservoirs and design methods to extract and transport oil.
1.1 Mechanisms
IMA: Ideal Mechanical Advantage = Distance effort moves / distance load moves
AMA: Actual Mechanical Advantage = Load / Effort
Efficiency: = AMA / IMA x 100% Nothing in the real world is more than 100% efficient.
Classification of Levels: Class 1, fulcrum in middle, class 2 load in middle, class 3 effort in middle
IMA of a lever: Length of effort arm/ length of load arm
IMA of a wheel and axel: radius of effort arm/ radius of load arm
IMA of a screw: circumference / pitch of screw (inches per thread) = πd/P
IMA of an inclined plane: Length of sloped side of ramp/ height of ramp
IMA of a wedge: Length of sloped side of wedge/ width of wedge
IMA of a pulley: Number of strands supporting load.
Compound Machines: MAtotal = MA1 X MA2
Work = Force · Distance (parallel)
Gears, sprockets and drive pulleys: Transform rotational energy by changing position, rotational directions, speed and torque.
n = number of teeth
d = diameter
ω = rotational speed (rpm)
τ = torque (in lbs or Nm)
n
d
GR
 out  out
1
nin
din

in
out

out
in
Driver: Causes motion (in)
Idler Gear allows the driver and driven gears to rotate in the same direction.
Compound Gear Train: Break down into simple gear trains and multiply
individual Gear Ratios.
Sprockets use chains: noisier, more expensive, stronger, need lubrication
Driver pulleys use belts: quieter, cheaper, weaker, no lubrication
1.2 Energy Sources
Nonrenewable: can be used up; oil, coal, uranium.
Renewable: more can be made; bio fuels, plants, animals
Inexhaustible: we don’t do anything to make more; solar, wind, hydroelectric
P
Work: Force x distance(parallel) (Joules)
Efficiency %  out  100
Mechanical Power: Work/Time (Watts)
Pin
Electrical Power P=IV (Watts)
MultiMeter:
Voltage – Set up circuit, measure across component.
Current – Multimeter bridges circuit; current must go through multimeter.
Resistance – Remove component from circuit, measure across component.
Quantities Abbreviations
Units
Symbols
Voltage
V
Volts
V
Current
I
Amperes
A
Resistance
R
Ohms
Ω
Voltage: (abb. V or E) – units are volts (V): Electromotive force: pressure or
force of electricity
Current: (abb. I) – units are amps (A) flow of electrons
Resistance: (abb. R) – units are Ohms (Ω): resistance to current flow
Ohms law: V = I * R
Power: P = V * I
Series Resistors: One path for current: Rtotal = R1+R2
Parallel Resistors: Multiple paths for current: 1/Rtotal = 1/R1+1/R2
1.3 Energy Applications
Hydrogen Fuel: Hydrogen fuel cells combine hydrogen and oxygen to create electricity; create no pollution, only water.
An emerging technology with many issues such as storage and distribution.
Thermodynamics: study of effects of work, heat flow, and energy on a system
Matter is made up of molecules in motion (kinetic energy), an increase in temperature increases motion
Absolute Zero: occurs when all kinetic energy is removed from a object 0 K = -273° C
Zeroth Law of Thermodynamics: If two systems are separately found to be in thermal equilibrium with a third system, first two systems are in thermal equilibrium
with each other.
1st law of thermodynamics: Energy cannot be created or destroyed.
2nd law of thermodynamics: thermal energy moves from hot to cold – Entropy (measure of disorder of energy) always increases.
Thermal energy can be transferred: convection (moving fluid), conduction (touching objects) or radiation (electromagnetic waves through space or air).
Rate of transfer: P= A*∆T/r-value = k*A *∆T / L where r-value is thermal resistance, T is temperature, A is area, L is length and k is thermal conductivity.
Heat Energy transfer: Q= m * Cp*∆T where Cp is specific heat capacity of a material and m is mass of object
Multiple Layers of Insulation: Add r-values of multiple layers to get total r-value. Design, construct, and test recyclable insulation materials.
2.1 Statics
Statics: used to mathematically analyze forces on a structure.
Newton’s First Law of Motion (Law of inertia): An object in a state of rest or
uniform motion will continue to be so unless acted upon by another force.
Newton’s Second Law of Motion: acceleration of an object is proportional to
net force acting on object and inversely proportional to object’s mass.
(F=MA)
Newton’s Third Law of Motion: For every action force, there is an equal and
opposite reaction force.
Static Equilibrium: No net external forces acting upon a particle or rigid body;
body remains at rest or continues at constant velocity.
Σ Moments (about a point) = 0; Σ Forces in x = 0; Σ Forces in y = 0
Moment: rotational forces acting on an object = Force * perpendicular distance.
Centroid: center of mass of an object and can be calculated from its dimensions.
Rectangle: = xmax/2; = ymax/2
Triangle: = xmax/3; = ymax/3
Semicircle: = radius; = 4r/ (3π)
Centroid of compound shapes: x = Σ (xi * Ai) / Σ xi, where xi is centroid of each
shape and Ai is area of each shape.
Moment of Inertia: describes stiffness of a beam due to its cross section
I = bh3/12 for a rectangular cross section with height of h and width of b
Max Deflection: describes how much it can bend ∆max= FL3 / (48 E I) where F is
applied force, L is length, I is moment of inertia and E is modulus of
elasticity, a property of material.
Free Body Diagrams: illustrate forces acting upon a given body including applied
and reaction and are a necessary step in solving for static equilibrium.
Normal Force: a reaction force perpendicular to surface the object touches.
Vector Quantities: have both magnitude and direction and trigonometry can be
used to break them down into x and y components.
Fx = F * cos(θ); Fy = F * sin(θ); θ = tan-1(Fy/Fx)
Resultant one vector, which has the same effect on a body as two or more
vectors that are actually acting on that body.
Solving for Static Equilibrium:
F
1. Assume body is rigid.
Fy
2. Choose a rotational point (with most unknowns go
through it) and solve for Σ M = 0
θ
Fx
3. Then solve for Σ Fx = 0, and Σ Fy = 0
2.2 Material Properties
Materials: are substances with which all objects are made, each with its own physical and chemical properties.
Elements: one type of atom – cannot be broken down
Compounds: multiple elements chemically bonded.
Mixtures: multiple elements or compounds not chemically bonded.
Material Classification: metallic, ceramic, organic, polymeric, and composite.
Recycling: an important consideration when choosing materials.
Material selection: based upon mechanical, thermal, electromagnetic, and chemical properties as well as cost.
Manufacturing Process: A sequence of operations and processes designed to create a specific product.
Engineers in Manufacturing
Manufacturing Engineer: Select and coordinate specific processes and equipment
Industrial Engineer: Responsible for manufacturing system design
Materials Engineer: Develop and select materials based on desired properties and manufacturing processes
Manufacturing System Designs
Job Shop
Small quantities of products
Large variety of products
Products move through shop to various machines
Flow Shop
Larger quantities of products
Production line
Special purpose machines
Linked-Cell Shop
Manufacturing and subassembly cells connected
Lean production system
One piece flow system
Project Shop
Product cannot be easily moved
Production processes are brought to product
Examples: Bridges, ships, large airplanes
Continuous Process
Large plants
Utilized in manufacture of liquids, oils, etc
Lean Manufacturing
100% “good” units flow from process to process
Integrated quality control (IQC)
All employees are inspectors
Basic Manufacturing Processes
Casting and Foundry Processes: In one step raw materials are transformed into
a desirable shape
Basic Casting Process: A mold is created – A cavity that holds molten material in
a desired shape until solidified
Forming and Metalworking Processes:
Rolling – Material passes through a series of rollers, reducing its thickness
Forging – Material is shaped by controlled application of force (blacksmith)
Extrusion – Material is compressed and forced through a die
Wire, rod, and tube drawing – Material is pulled through a die
Cold forming and forging – Slugs of material are squeezed into dies
Machining Processes
Turning Processes: Operations that create cylindrical parts, Work piece rotates as cutting tool is fed into work
Lathes and turning centers processes include: Straight, taper, contour turning, facing, forming, necking, parting, boring, threading, and knurling
Milling Processes: Operations that create flat or curved surfaces by progressively removing material
Cutting tools rotate as work piece is secured and fed into tool
Mills – Vertical and horizontal
Processes include: Surfacing, shaping, forming, slotting, T-slotting, angle, straddle, dovetailing, and slab milling
Drilling Processes: Operations that create holes
Cutting tools rotate and are fed into nonmoving secured work pieces
Drilling and boring machines
Processes include: Drilling, counter drilling, step drilling, boring, counter boring, countersinking, reaming, spot facing, and tapping
Shearing Processes: Breaks unwanted material away from part
Movable surface (blade, die, or punch) applies a force to part, shears away unwanted material.
Automated hole punch, squaring shear, and rotary cutter
Processes include: Shearing, blanking, cutoff, and parting; punching, perforating, and slotting; notching, lacing, and trimming
Abrasive Machining Processes: Operations in which small particles of materials (abrasives) remove small chips of material upon contact
Drum, disc, and belt sanders; surface, vertical and horizontal spindle; disc grinders; media blaster; tumblers
Thermal and Chemical Processes: Operations that cut and shape materials through chemical means
No mechanical force is used
Electrical discharge, electrochemical, chemical, laser, electron beam, flame cutting, and plasma-arc cutting
Processes include: Grinding, sawing, cutting, machining, milling, blanking, and etching
Controlled heating and cooling of a material to alter its properties while maintaining its shape
Properties include: Strength, toughness, machinability, wear resistance, and corrosion resistance
90% of heat treating is preformed on steel and other ferrous metals
To aid in manufacturing process, materials can be treated to be weak and ductile and then can be re-treated to provide high strength.
Joining and Assembly Processes
Plastics Manufacturing Processes
Most products consist of multiple parts that are assembled to form a finished
product.
Mechanical Fastening: Use physical force to hold parts together
Mechanical fasteners or part design
Screws, bolts, nails, rivets, cotter pins, retaining clips, and edge design
Welding: Operations that use heat, pressure, or both to permanently join parts
Gas, arc, stud, spot, forge, roll laminating, resistance, and induction welding
Adhesive bonding: Bonding of adjoining surfaces by filling gap between each
surface with a bonding material
Glue, cement, thermoplastic, thermosetting, and elastomers
Soldering and Brazing: Operation in which metal surfaces are bonded together
by an alloy
Heated molten alloy flows between adjoining surfaces
When heat is removed, molten metal solidifies and metal surfaces are bonded
Rapid Prototyping: Additive process; parts are produced directly from software
applications
Common rapid prototyping systems include: stereolithography (SLA), selective
laser sintering (SLS), fused deposition modeling (FDM), laminated object
manufacturing (LOM), digital light processing (DLP)
Finished parts can be field tested depending upon building material
Created parts can be used to create a mold
Modifications to design can be implemented quickly
Extrusion: A rotating screw forces plastic through a heating chamber and then
through a heated die
Produces long plastic parts with uniform cross sections
Injection Molding: Heated plastic is forced by a movable plunger through a
nozzle and then into a mold. Material fills mold and then is cooled.
Most widely used high-volume production process
Casting: Plastic is melted and poured into a mold – No pressure or fillers are
required.
Rotational Molding: A closed mold is filled with a predetermined amount of
plastic. Mold is heated, rotated, and then cooled to create a hollow plastic
object with uniform wall thickness.
Blow Molding: A solid bottom hollow tube is placed between two mold halves
and heated. Heated tube is then expanded into sides of mold with
compressed air.
Thermoforming: Plastic sheets are heated over an open mold to a working
temperature. Once workable, a vacuum is applied to mold, forcing plastic
sheet to take shape of mold.
Reaction Molding: Liquid reactants are mixed and then pressurized into a mold.
No heat is needed. Curing time is typically less than 1 minute.
Tensile Testing - Stress Strain Curve
Ceramic Manufacturing Processes
Glass is heated to a molten state, shaped by viscous flow, and then cooled
to produce a solid.
Crystalline Ceramics: Material is shaped and then heated to produce a
permanent solid.
2.3 Material Testing
Tensile Stress Test: Measures the deformation and breaking point of a test sample under static
tensile force.
Hardness test: Brinell or Rockwell hardness measures a material’s resistance to a probe creating
a crater in it.
Non-destructive test: properties such as density and conductivity may be tested without
damaging the material, but others such as strength and hardness require destructive tests.
Stress: (σ) Externally applied – depends on force and material’s shape = F/A for tensile stress.
Strain: (ε) material’s response to stress = change in length / original length.
Deformation: (δ) elongation - how much the length of a sample changes under stress
Elastic range: Linear portion of stress / strain curve. Material isn’t permanently changed.
Elastic Limit: (Proportional limit or Yield point) Plastic deformation (permanent change) starts to occur.
Resilience: area under the linear portion of the curve. Measure the energy needed to permanently deform the material
Ultimate Tensile Strength: maximum tensile stress, the peak of the curve.
Ductility: Amount of plasticity before fracture, measures how much the material can be stretched.
Modulus of Elasticity: (E) a measure of how much a material resists stretching = σ/ε also = PL/Aδ where P is the axial force, L is the original length, and A is the cross
sectional area.
3.1 Machine Control
Flow Chart: a graphical representation of a program.
 Rectangle: process or action
 Rounded Rectangle: start or end
 Parallelogram: input (from real world to program) or output (from program to the real world)
 Rhombus: decision or a branch
Digital: a system that uses discrete values, commonly two states two, on/off, 0/1, etc. (ex. limit switch, phototransistor)
Analog: variable signal, might appear anywhere in a range. (ex. photoresistor, NTC resistor)
Open Loop: No feedback, relies on timing, un-repeatable
Closed Loop: feedback tells program it is done, more repeatable
Normally open: no connection until switch is pressed
Normally closed: connection until switch is pressed
3.2 Fluid Power
Fluid Power: relies on pressure of a liquid or a gas to transmit force over great distances, multiply an input force, and increase the distance that an output will move.
Pneumatic Power: uses gas – faster, cleaner, requires a lubricant
Hydraulic Power: uses a liquid – stronger, more precise, higher pressure
Basic components: of a fluid power systems include a reservoir or receiver, a pump or compressor, a valve, and a cylinder.
Pascal’s Law: Pressure is the same everywhere within a non moving system P = F/A
Boyle’s Law: Pressure and volume are inversely related P1/P2 =V2/V1
Charles’ Law: temperature and volume are directly related T1/T2 =V1/V2
Gay-Lussac’s Law: Pressure and temperature are directly related P1/P2 = T1/T2
Absolute Pressure: = measured pressure + atmospheric pressure (14.7 psi at sea level) – always use this when applying Boyle’s law or Gay-Lussac’s Law.
Absolute Temperature: = Temperature above absolute zero = 460° + °F or 273° + °C – always use this when applying Charles’ law or Gay-Lussac’s Law.
4.1 Statistics
Experimental Data: always has some error – large samples can be characterized using statistics.
Centrality measures: Mean (sum/# of samples), median (middle value) or mode (most common value) gives us an idea
of the true value.
Variability measures: range and standard deviation give us an idea of how repeatable our measure is
Range: Difference between the lowest and highest data value
Standard Deviation: Square root of the variance
s for a sample, not population
Calculate (the mean)
Subtract the mean from each value and then square it.
Sum all squared differences.
Divide the summation by the number of values in the array minus 1.
Calculate the square root of the product.
Probability: The calculated likelihood that a given event will occur
Empirical: Experimental observation (Ex. Process control)
Theoretical: Uses known elements (Ex. Coin toss, die rolling)
Subjective: Assumptions (Ex. I think that . . . )
Experiment: An activity with observable results
Sample Space: A set of all possible outcomes
Event: A subset of a sample space
Outcome / Sample Point: The result of an experiment
4.2 Kinematics
Displacement: straight line distance and direction from initial point
Speed: a scalar quantity describing distance traveled / time
Velocity: a vector quantity with both speed and direction
Acceleration: a change in velocity per unit time.
Gravity: will cause a constant acceleration (ignoring air resistance) of -32.2 ft /sec 2 or -9.8 m/sec2
Projectile: a non-powered object moving through the air; its final displacement can be calculated from
its initial velocity.
Its x component of velocity is constant while the y component changed due to gravity.
Initial Velocity
Vi 
gx
sin  2 
Horizontal Distance
x
Vi2
sin  2 
g
Firing Angle
  gx 
2  sin1  2 
 Vi 
Vi

x
Vi  Initial Velocity
g  Gravitational Acceleration
x  Horizontal Dis tance Traveled
  Firing Angle