Machinery Installation & Alignment
20%of exam
Precision Measurement
15%of exam
Bearings & Lubrication
20%of exam
Pumps & Mechanical Seals
20%of exam
Conveyors, Compressors & Turbines
25%of exam
Quick Facts
- Exam
- NCCER Millwright
- Credential
- NCCER Registry
- Questions
- 100 multiple-choice
- Time
- 2 hours
- Pass
- 70%
- Level
- Journey-level
- Curriculum
- 4 levels (2021 ed.)
- Expires
- Never (Registry)
Alignment Sequence
Level, Soft Foot, Rough, Fine, Dowel
Level: baseplate flatSoft foot: shim firstRough: jackscrews closeFine: dial/laser finalDowel: lock position
Rim-and-Face vs Reverse-Indicator
Rim-and-Face
- One shaft's rim + face
- Needs a solid face
- Axial float risk
Reverse-Indicator
- Both shafts' OD only
- No face reading
- Avoids float error
Face-dependent vs face-free
Alignment Method Picker
- No face reading wanted→Reverse-indicator(Two brackets)
- Face surface is reliable→Rim-and-face(Axial float risk)
- Fast rough check only→Straightedge + feeler(Visual pass)
- Tight final tolerance→Laser alignment(Digital readout)
- Multiple baseplate elevations→Optical level(Room reference)
- Machine runs hot→Cold target offset(Thermal growth)
Hand Tools & Fasteners
- Ball peen hammer
- Strikes chisels, sets rivets
- Box-end wrench
- Grips all six bolt points
- Tap and die
- Cut new internal/external threads
- SAE Grade 5
- Three radial lines on head
- SAE Grade 8
- Six radial lines on head
- Right-hand thread
- Tightens clockwise
- Wedge anchor
- Steel clip expands in concrete
- Sleeve anchor
- Sleeve expands as bolt tightens
- Epoxy anchor
- Adhesive bonds bolt to concrete
Foundations & Installation
- Soft foot
- Frame twists once bolted down
- Star bolt pattern
- Even, progressive clamping force
- Jackscrews
- Fine-tune position before bolt-down
- Dowel pins
- Lock final aligned position
- Grouting
- Fills the baseplate void
- Baseplate
- Fixed machine mounting surface
- Thermal growth
- Casing expands as it heats
- Woodruff key
- Self-aligns on tapered shafts
- Gib-head key
- Angled head drives out easily
Shaft Alignment
- Offset misalignment
- Parallel centerlines, shifted sideways
- Angular misalignment
- Centerlines meet at an angle
- Reverse-indicator method
- No face reading needed
- Rim-and-face method
- Reads rim plus coupling face
- Bar sag
- Bracket deflection error to subtract
- Cold alignment target
- Preset offset before startup
- Laser alignment
- Digital shaft offset readout
- 12-3-6-9 readings
- Separate vertical from horizontal
- Shim
- Corrects vertical position only
Rigging & Safety
- Personnel-hoist rigging
- Needs a 5:1 safety factor
- Suspension scaffold rope
- Needs a 6:1 safety factor
- Sling angle
- Shallower angle raises leg tension
- Center of gravity
- Must hang directly under hook
- LOTO
- Physically isolates every energy source
- Hard hat Type I
- Top-impact protection only
- Hard hat Type II
- Top plus lateral protection
- Class G hard hat
- Protects up to 2,200 volts
- Class E hard hat
- Protects up to 20,000 volts
- Bench grinder gap
- Work rest within 1/8 inch
Micrometer vs Dial Indicator
Micrometer
- Absolute size
- Thousandths of an inch
- Static dimension
Dial Indicator
- Relative movement
- Runout/alignment use
- Zero-reference change
Size vs movement
Precision Measuring Tools
- Micrometer
- Reads size to 0.001 in
- Vernier scale
- Adds 0.0001 in resolution
- Dial indicator
- Reads relative movement, runout
- Feeler gauge
- Checks a static gap
- Bore gauge
- Measures internal bore diameter
- Optical level
- Sets a room reference plane
- Straightedge
- Checks baseplate flatness
- Torque wrench
- Verifies bolt clamping force
- Stroboscope
- Checks rotating shaft speed
Trade Math & Blueprints
- Taper per foot
- Diameter change over shaft length
- Sheave ratio
- Speed is inverse of diameter
- Gear reducer ratio
- Speed down, torque up
- Hidden line
- Short dashes, edge not visible
- Centerline
- Marks an axis of symmetry
- Detail drawing
- One part, full dimensions
- Assembly drawing
- Shows multiple parts together
- P&ID
- Piping and instrumentation diagram
Vibration Frequency
1X Means Unbalance, 2X Means Misalignment
1X: rotor weight2X: coupling misalignmentBearing tone: race defectBroadband: looseness
True vs False Brinelling
True Brinelling
- Static overload or impact
- Permanent race dent
- Single event cause
False Brinelling
- Vibration while stationary
- Fretting wear pattern
- No overload event
Impact vs fretting
Bearing & Vibration Diagnosis
- Static overload dent→True brinelling(Impact damage)
- Marks with no overload→False brinelling(Shipping fretting)
- Flaking or pitted race→Spalling(Fatigue failure)
- Peak at 1X RPM→Suspect unbalance(Rotor weight)
- Peak at 2X RPM→Suspect misalignment(Coupling stress)
- Install without impact→Induction heater(Below 250°F)
- Over-filled grease housing→Drop to half full(Prevent overheat)
Bearing Types & Failure
- Anti-friction bearing
- Uses rolling balls or rollers
- Plain/sleeve bearing
- Relies on an oil film
- Tapered roller bearing
- Handles radial plus thrust load
- Thrust bearing
- Absorbs axial load only
- L10 life
- 90% survive that rating
- True brinelling
- Static overload dents the race
- False brinelling
- Fretting wear while stationary
- Spalling
- Fatigue flaking of the race
- Heat limit
- Stay below about 250°F
L10 Bearing Life
L10 Equals 90 Percent Still Surviving
10% may fail earlyStatistical, not guaranteedHigher load shortens L10
Grease vs Oil
Grease
- Stays in place
- Low maintenance
- Moderate speed use
Oil
- Better heat removal
- Can filter and circulate
- High-speed, high-temp use
Simplicity vs cooling
Lubrication
- NLGI Grade 2
- Most common grease consistency
- ISO VG 68
- Oil viscosity centered at 68 cSt
- Grease
- Low maintenance, stays in place
- Oil
- Better cooling, high-speed use
- Fill level
- One-third to one-half full
- Oil analysis
- Tracks wear-metal trends
- Thermography
- Finds abnormal heat patterns
Grease Fill Rule
Fill One-Third To One-Half, Never Full
Full housing overheatsChurn needs air spaceOver-grease is a real risk
NPSH Rule
Keep NPSH Available Above NPSH Required
NPSHa: system sideNPSHr: pump specMargin avoids cavitation
Centrifugal vs Positive-Displacement Pump
Centrifugal
- Flow varies with pressure
- Throttle changes output
- No relief valve needed
Positive Displacement
- Fixed volume per revolution
- Needs a relief valve
- Pressure builds if blocked
Variable vs fixed flow
Pump Problem Picker
- Pitted, noisy impeller→Check NPSHa margin(Cavitation)
- Lost prime, no pitting→Check for gas binding(Air ingress)
- Discharge fully closed→Open valve or relief(Dead-head heat)
- Seal leaking, scored faces→Check the flush plan(API plan)
- Flow and head both drop→Check wear rings(Internal recirculation)
Pumps
- Centrifugal pump
- Flow varies with pressure
- Positive-displacement pump
- Fixed volume per revolution
- NPSH required
- Pump's own suction spec
- NPSH available
- System's actual suction margin
- Cavitation
- Vapor bubbles collapse, pit impeller
- Gas binding
- Air displaces liquid, loses prime
- Dead-heading
- Closed discharge overheats fluid
- Wear ring clearance
- Controls internal fluid recirculation
Cavitation vs Gas Binding
Cavitation
- Local pressure drops
- Vapor bubbles collapse
- Pits the impeller
Gas Binding
- Air or gas enters suction
- Displaces liquid at eye
- Loses prime, no pitting
Vapor collapse vs air displacement
Mechanical Seals & Sealing
- Mechanical seal
- Two lapped faces, near-zero leak
- Packing gland
- Controlled drip cools packing
- Flush plan
- Cools and cleans seal faces
- O-ring
- Static or dynamic elastomer seal
- Spiral wound gasket
- High-temperature, high-pressure joints
- Cork composite gasket
- Lower pressure, lower cost joints
Mechanical Seal vs Packing Gland
Mechanical Seal
- Two lapped faces
- Near-zero leakage
- Higher cost, precision
Packing Gland
- Compressed packing rings
- Controlled drip cools it
- Simpler, more upkeep
Sealed vs designed-to-leak
V-Belt vs Timing Belt
V-Belt
- Wedges into a groove
- Friction-based grip
- Some slip possible
Timing Belt
- Toothed engagement
- Positive, slip-free drive
- Exact synchronization
Friction vs positive drive
Drive System Picker
- Need slip-free timing→Timing belt(Toothed drive)
- Need max friction torque→V-belt(Wedge grip)
- Light duty, low torque→Flat belt(Surface friction)
- Need positive chain drive→Roller chain(Check elongation)
- Increase torque, cut speed→Gear reducer(Same power)
- Incline conveyor loses power→Backstop device(Blocks runback)
Belt, Chain & Gear Drives
- V-belt
- Wedges into a grooved pulley
- Flat belt
- Plain surface friction only
- Timing belt
- Toothed, positive, slip-free drive
- Over-tensioned belt
- Overloads bearings and shafts
- Under-tensioned belt
- Slips, glazes, and overheats
- Chain elongation
- Pin and bushing wear adds up
- Gear reducer
- Trades speed for more torque
- Backstop
- Blocks reverse runback on inclines
- Belt tracking
- Tension, crown, or buildup issue
Compressors & Turbines
- Reciprocating compressor
- Piston compresses gas in pulses
- Rotary screw compressor
- Continuous meshing-rotor compression
- Intercooling
- Removes heat between compression stages
- Governor
- Holds turbine speed under load
- Radial clearance
- Tight blade-to-casing gap
- Axial thrust
- Rotor pushed along its axis
- Thrust bearing
- Absorbs that axial force
Hydraulics & Pneumatics
- Pascal's law
- Pressure transmits equally in fluid
- Force = pressure x area
- Sizes cylinder output force
- Hydraulic reservoir
- Stores, cools, settles the fluid
- FRL unit
- Filters, regulates, lubricates air
- Double-acting cylinder
- Force in both directions
- Single-acting cylinder
- Force one way, spring returns
Common Traps
Micrometer vs dial indicator
Micrometer reads part size ≠ Dial indicator reads movement
True vs false brinelling
True = impact damage ≠ False = fretting wear
Cavitation vs gas binding
Cavitation collapses vapor bubbles ≠ Gas binding traps entrained air
NPSHa vs NPSHr
NPSHa = system's margin ≠ NPSHr = pump's spec
5:1 vs 6:1 rigging factor
Personnel-hoist rigging needs 5:1 ≠ Suspension scaffold rope needs 6:1
1X vs 2X vibration
1X peak signals unbalance ≠ 2X peak signals misalignment
Hard hat Class G vs E
Class G caps at 2,200V ≠ Class E caps at 20,000V
Last Minute
- 1.Exam: 100 questions, 2 hours, 70%
- 2.Weights: 20-15-20-20-25 by domain
- 3.Micrometer = size; indicator = movement
- 4.Reverse-indicator needs no face reading
- 5.Shims correct vertical position only
- 6.1X = unbalance; 2X = misalignment
- 7.Heat bearings below 250°F only
- 8.L10 = 90% survive rating
- 9.Grease fills one-third to half
- 10.Keep NPSHa above NPSHr always
- 11.Cavitation = vapor; gas binding = air
- 12.Scaffold rope factor is 6:1
- 13.Personnel-hoist rigging factor is 5:1
- 14.LOTO isolates energy, not just off
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