3.2 Crimp Quality Assurance

The

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Measurement

3.2.2 What a functional tester looks like (block view)

• MatingThe fixturesTool:: realMeasurements connectorsmust be taken with a specialized blade-micrometer or guided"crimp pogomic" arrays;(point-to-flat). keyed,Standard withflat-jaw replaceablecalipers wearcannot parts.be used because they bridge the curvature of the crimp bottom, giving a false high reading.
• SwitchThe matrix / relaysTarget:: routeThe loads/stimuliheight tois any net; isolate sensitive lines.
• Programmable loads & sources: DC supplies, electronic loads, PWM drivers, coil drivers, lamp loads.
• Sense & protection: Kelvin sense on power nets, high-side current sense, fast fusing/foldback.
• Comms emulators: CAN/LIN/RS-485/UART/USB/Ethernet loopbacks or nodes.
• Motion/perturbation: wiggle bars / mild shaker / flex mandrels to reveal intermittents.
• Guarding: interlocked lid, E-stop, HV/HOT indicators.
• Software: selects programdefined by scanthe ofterminal PN–Rev–Variant;manufacturer's pushesspecification resultsfor tothe MESspecific bywire SN (20.5).

3.2.3 Core tests (in a safe order)

1. Low-current functional
2. • Switches/sensors: debounce and logic states.
   • Comms physical: presence/ID, proper terminationgauge (e.g., CAN1.15 ≈mm ± 0.05 mm).
   • Process Control: Crimp height is a Critical-to-Quality (CTQ) characteristic. Automated presses usually include 120Crimp ΩForce Monitors (CFM) bus).
2. Loadthat &detect drop
3. • Driveheight eachvariations powerby netmeasuring atthe 50–100%force rated current; measure Vdrop end-to-end and per contact (Kelvin).
   • Compute R = V/I, log per path.
3. Thermal settle
4. • Hold worst-case load 2–5 min; measure ΔT at connectors/suspect splices (IR camera or stick-on dots).
4. Wiggle under load
5. • Flexrequired to close the drawing’s min radius; cycle bends 30–60 s while logging dropouts & Vdrop jitter.
5. Dynamic profiles (if applicable)
6. • Crank profile, PWM ramps, relay chatter, inrush.

Stop on unsafe current/heat; record partial data for analysis.

3.2.4 Power & ground paths (numbers that help)

• Target drop: as engineered in 19.1; if none given, start with ≤ 5% of rail at full load and ≤ 50 mV per mated contact on low-voltage power (tune to vendor spec).
• Temperature rise: ≤ 30 °C over ambient at steady load for tin contacts (use vendor limits if tighter).
• Symmetry: parallel returns should be within 10% drop of each other.die.

Tip:Action: logMeasure 5 pieces at setup. If the mean height is not centered within the tolerance window, adjust the applicator dial. Do not run production at the edge of the specification limits.

3.2.2 Pull Testing: Destructive Verification

The VdropPull vs currentTest atverifies 25/50/75/100%mechanical totensile catchstrength. non-linearIt contactensures behaviorthe (fretting/oxidation).wire will not separate from the terminal under tension or vibration.

Test

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3.2.5 Intermittents & contact fretting (how to catch the sneaky ones)

• Glitch monitorFrequency:: sample continuityMandatory at ≥1 kHzSetup while flexing; flag any open >, 1Material msChange (choosenew perwire productspool), risk)Tool Change, and at defined intervals (e.g., start/end of shift).
• Method: The wire is pulled axially from the terminal at a constant speed (typically 25 to 50 mm/minute). Jerking or snapping the wire gives invalid results.
• Failure Modes:
  • Pull Out: The wire slips out of the crimp. This indicates under-compression (crimp height too high).
  • Jitter metricBreak:: standardThe deviationwire ofsnaps outside the crimp area. This is the Vdroppreferred failure mode, indicating the crimp is stronger than the wire itself.
  • Tear: duringThe wiggle;terminal suddentears spikesor implybreaks. micro-opens.Acceptable if the force exceeds the minimum.

Minimum Force Requirements (Reference: UL 486A / IPC-620)

• 22 AWG: 36 N (8 lbs)
• Connector20 cycling: mate/unmate 5–10×AWG: during58 NPI;N watch(13 lbs)
• contact18 RAWG: drift.89 N (20 lbs)
  
• 16 AWG: 133 N (30 lbs)

Warning:

3.2.6A Protocol-awarecrimp can pass the pull test but fail electrical resistance checks (quick,e.g., honest)if the crimp is slightly loose but holds mechanically). Therefore, Pull Testing must always be paired with Crimp Height Measurement.

3.2.3 Micro-Section Analysis: The Ultimate Validation

Micro-sectioning involves cutting the crimp in half, polishing the face, and inspecting the interior under a microscope. It is the only way to "see" the cold weld.

Analysis Criteria

1. Void Percentage: Large voids indicate insufficient compression. The target is a "honeycomb" structure with minimal gaps.
2. Symmetry: The two crimp wings should curl symmetrically and touch (or nearly touch) at the bottom.
3. Wing Closure: The wings should support each other but not pierce the bottom of the terminal barrel.
4. Strand Count: Verifies that no strands were missed during insertion.

Mandate: Micro-sections are required for Class 3 setup validation and whenever a new wire/terminal combination is introduced.

3.2.4 Defect Atlas: Visual Cues

Visual inspection is the final gate. Inspectors must check for machine setup errors that distort the terminal.

Defect Name	Appearance	Root Cause	Risk
Banana (Bending)	Terminal is bent up or down relative to the wire axis.	Damage to the carrier strip; excessive Crimp Force; incorrect anvil alignment.	Mating alignment failure; connector damage.
Flag / Twist	Terminal is twisted or bent sideways.	Misalignment in the applicator feed track.	Terminal will not fit into the connector housing.
Cut Strands	Individual wire strands are severed at the bellmouth.	No bellmouth present (sharp edge); Crimp Height too low (over-compression).	High resistance; potential arc/fire; mechanical failure.
Insulation Entrapment	Wire insulation is pinched inside the conductor crimp area.	Strip length too short; wire inserted too far.	High Electrical Resistance; intermittent connection (insulator blocks the metal-to-metal contact).
Insulation Support Failure	Insulation crimp pierces the jacket or does not grip it at all.	Wrong insulation diameter setting; wrong terminal size.	Wire breaks due to fatigue (no strain relief).

Final Checklist: Crimp Quality Controls

InterfaceMandate	What to simulateCriteria	PassVerification cuesAction
CAN/LINHeight Verification	ProperCrimp terminationheight must measure within the manufacturer's spec (e.g., ~120± Ω0.05 mm CAN), dominant/recessive levels, node transceiver).	BusMeasured levelswith inBlade spec;Micrometer framesat echosetup withoutand errorsevery batch change.
RS-485Mechanical Strength	Pull TestBias/termination, A/Bforce polaritymust exceed UL/IPC minimums for the wire gauge.	IdleDestructive biastest correct; loopbackperformed at 115.2Setup kbpsand passeslogged. Preferred failure mode is "Wire Break."
USBInternal Integrity	Micro-section5 Vshows drophoneycomb @compression 900and mAsymmetric (USB3),wing shield bond, D+/D− continuityclosure.	DropPerformed ≤during limit;New deviceProduct enumeratesIntroduction on(NPI) fixtureor Class 3 validations.
EthernetVisual Geometry	MagneticsNo present,Banana, pairTwist, mapping,or shieldmissing Bellmouth defects.	Link100% up;visual paircheck swap/crossby flaggedthe operator immediately after crimping.
SensorsEntrapment (4–20 mA, PT100, NTC)Check	Zero insulationSource/sink current,allowed senseinside readingthe withinconductor rangecrimp barrel.	ReadoutsVisual withininspection table limits

Keep it functional-light: we prove harness health, not firmware features.

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3.2.7 Loads & sources (recipes that behave)

• Electronic loads for DC rails; slew-rate limit to avoid violent inrush unless you are testing inrush.
• Relay/coil banks for inductive nets; add flyback as inof the real"window" product.
• Lamp/filamentbetween simulatorsthe for automotive style loads (inrush ≈ 10×).
• PWM drivers for dimmers/motor leads (test at duty steps 10/50/90%).
• Current clamps with 1% accuracy for cross-check; log at 10–100 Hz.
  

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3.2.8 Fixture design (fast, durable,insulation and kindconductor to pins)

• Use mating connectors whenever possible; pogo only for robust round pins.
• Rated current on every contact/pogo; short, heavy bus bars for high A.
• Kelvin points brought out near each contact for accurate R.
• Replaceable tips/inserts; count cycles and PM (18.1).
• Color/shape coding by variant; scanner blocks the wrong fixture.
  

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3.2.9 Example starter limits (tune for your product)

Test	Starter limit
Drop per mated power contact @ rated I	≤ 50 mV (or vendor spec)
Total harness drop (source→load)	Per 19.1 calc, ≤ 1.5× expected
Temp rise at connector shell	≤ 30 °C over ambient after 5 min
Glitches during 60 s wiggle	0 opens > 1 ms; ≤3 brief blips <1 ms
CAN termination	110–130 Ω between CAN_H/L
Shield continuity to chassis	< 0.1 Ω end-to-end or to bond pointcrimps.

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3.2.10 Safety first (load test edition)

• Interlocked lid; E-stop; guarded HV/HOT.
• Fused outputs and foldback on supplies.
• Discharge any bulk capacitance before lid unlocks.
• One-hand rule; no ESD strap when high energy is exposed.
• Daily self-test: fixture ID, relay click test, load zeroing.
  

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3.2.11 Recording (what to store with the SN)

• Program/fixture IDs, operator, ambient Temp/RH.
• For each loaded net: I, Vdrop, R, ΔT, pass/fail.
• Glitch counts/timestamps; comms pass bits.
• Photos if the station requires.
• All tied to the harness SN (20.5).
  

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3.2.12 Common traps → smallest reliable fix

Trap	Symptom	Fix
Testing only at no-load	Pass in test, fails in field	Add load & wiggle; log Vdrop and ΔT
Pogo pins undersized	Melted tips, false fails	Use mating connectors or higher-A pogo; shorten paths
No Kelvin sense	Drop includes leads	Add sense lines at the DUT side
Over-aggressive inrush	Nuisance trips	Slew-limit or pre-charge; then run a separate inrush test
Variant mix	Wrong pins driven	Scan-to-select program/fixture; color/shape code
No thermal check	Hot, “passing” harnesses	Add IR spot or temp dots at connectors

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3.2.13 Pocket checklists

Before test

• Program selected by scan (PN–Rev–Variant)
• Fixture mated; fans/guards OK; loads zeroed
• Kelvin clips on power paths; thermals ready

Run

• Low-current functional PASS (switches, sensors, IDs)
• Load at 25/50/75/100%; log V, I, Vdrop
• Hold worst case 2–5 min; record ΔT
• Wiggle at min radius; glitch monitor 0 >1 ms

Close

• Results to SN; any fails to NG-QUAR with plot
• Fixture PM counter ticked; worn tips replaced
• One kaizen note if time was lost
  

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When harnesses are proven under load, with temperature, voltage, and intermittent behavior logged to each serial number, hidden faults are eliminated before they can escape. The payoff is fewer field failures, stronger customer confidence, and production that runs with fewer surprises.