TL;DR: pass-through harness skal designes som connector, seal og strain relief i samme system
- Start med wall thickness, cable OD, bend radius, pull load og sealing target før connector geometry låses.
- Custom mold development kræver prototype gating, materialevalg, pull test og first article section evidence.
- IPC-A-620, UL-758 og IATF 16949 giver bedre release-sprog end “custom connector, supplier design”.
- RFQ'en bør kræve 3D envelope, wire list, overmold material, test limits og change-control triggers.
A US headquarters engineering contact requested a 10-core pass-through wire harness for a new power-equipment project, and the challenge was not only wiring 10 conductors. The build required Custom mold development required and Custom connector design, so the early engineering review had to define how the harness would pass through a panel, seal the opening, survive cable pull, and keep each circuit testable before the custom tooling moved forward.
A pass-through wire harness is a wire harness that carries conductors through a wall, enclosure, machine panel or molded interface while maintaining mechanical retention and electrical continuity. Custom mold development is the tooling and process work used to form a repeatable molded body around cable, wires, inserts or connector features. Molded strain relief is a flexible or semi-rigid transition that spreads cable bending and pull load away from terminals, seals and conductor exits.
Denne guide er skrevet til design engineers, sourcing managers og NPI teams, der er i RFQ-, prototype- eller pilotbatch-stadiet for custom wire harness, custom cable assembly eller custom molded cable assembly. Rollen er senior factory engineer med mere end 20 års erfaring i wire harness og cable assembly produktion til industrial, automotive, medical, robotics og power-equipment programmer. Objective er at vise, hvordan du specificerer en pass-through harness, så supplieren kan quote, prototype, teste og frigive den uden skjulte connector-, mold- eller sealing-risici.
— Hommer Zhao, Grundlegger & CEO: Når et pass-through harness kræver custom mold, vil jeg se wall thickness, cable OD, minimum bend radius og pull load før tooling quote. Hvis de fire tal mangler, designer du formen blindt.
Hvorfor pass-through wire harness design fejler sent
Pass-through assemblies fejler ofte sent, fordi mekanik og elektrisk design bliver reviewet hver for sig. Wiring teamet validerer pinout. Mechanical teamet tegner panel opening. Purchasing sender en connector note. Factoryen får derefter en RFQ, hvor den virkelige risiko ligger i grænsefladen mellem de tre områder: cable exit, sealing surface, molded body, conductor spacing, strain relief og test access.
Den svage specifikation er “custom pass-through connector per supplier recommendation.” Den kan ikke frigives med målinger. En konkret substitution er: “10 conductors through panel, wall thickness 2.0-3.0 mm, cable bundle OD 8.8-9.4 mm, molded body material TPE 70 Shore A or approved equivalent, minimum static bend radius 8 x cable OD, axial pull sample test 80 N for 60 seconds, 100% continuity, insulation resistance sample test, first article dimensional report and section review.” Tallene skal justeres til dit produkt, men strukturen gør RFQ'en producerbar.
For overmolding capability er det også en tooling-disciplin. Gate location, preheat, insert retention, cable jacket compatibility, venting og cooling påvirker om molded body binder, revner eller efterlader voids omkring conductor exits. For waterproof wire harness skal sealing target, dunk test eller pressure test defineres separat. Et overmold kan give strain relief, men det beviser ikke automatisk IP67 eller chemical resistance.
Sammenligning: pass-through designvalg før RFQ
| Designvalg | Bedst når | Kritisk input | Risiko hvis det mangler | Releasekriterium |
|---|---|---|---|---|
| Standard cable gland | Panel hole, round cable og serviceable installation | Cable OD, thread, wall thickness og torque | Forkert compression eller dårlig bend support | Fit check, pull check og sealing sample efter drawing |
| Custom molded pass-through | Compact envelope, shaped exit eller permanent assembly | 3D envelope, mold material og cable jacket | Tooling rework, voids eller jacket delamination | First article dimensions, section review og pull test |
| Insert-molded connector body | Connector geometry og panel latch skal være integreret | Terminal spacing, latch load og resin flow path | Terminal shift eller latch deformation | Cavity inspection, retention check og mating-cycle sample |
| Grommet pass-through | Lower volume og elastomer seal omkring bundle | Panel cutout, durometer og bundle OD window | Seal roll-out eller cable movement | Installation force, compression witness og leak sample |
| Potting cup transition | Electronics enclosure eller strain relief around mixed wires | Potting depth, cure, wire spacing og exotherm limit | Air pockets, hard spot eller service rework block | Void inspection, cure record og continuity after cure |
| Modular bulkhead connector | Frequent service disconnect eller replaceable modules | Current rating, pin count, keying og seal family | Oversized BOM eller wrong terminal system | Mating test, terminal retention og 100% electrical test |
Tabellen viser, at custom mold ikke altid er det rigtige første valg. Hvis en standard gland klarer pull load, sealing og service access, kan den reducere tooling cost. Hvis assemblyen har shaped exit, narrow envelope, unique panel latch eller customer-owned connector geometry, er custom mold ofte den eneste måde at gøre designet repeatable på.
Standarder og release-sprog til pass-through harness
IPC-A-620 via IPC giver et fælles workmanship-sprog for cable and wire harness assemblies, herunder conductor damage, crimp accept, insulation clearance, soldered wire connections og visual acceptance. For en pass-through harness er standarden nyttig, fordi molded eller grommeted geometry ikke må skjule en dårlig crimp, cut strand eller forkert insulation support.
UL-758 via UL er relevant, når wire style, voltage rating, temperature rating og insulation material skal fastholdes gennem sourcing og substitutions. En custom molded body kan være dimensionelt korrekt og stadig fejle compliance, hvis alternate wire ændrer OD, jacket adhesion eller temperature class. For automotive-style launch discipline bør IATF 16949 bruges som reference for traceability, change control, reaction plans og lot records.
Hvis kunden kræver enclosure sealing, kan IEC 60529 IP Code bruges som public reference for IP ratings, men produktets faktiske test skal skrives med metode, tid, dybde eller pressure. Sætninger som “waterproof pass-through” og “sealed connector” er ikke testbare. Skriv i stedet sample size, conditioning, water depth, duration, allowed leakage og electrical retest after exposure.
Fabriksscenario: 10-core harness før custom tooling
I engineering review for det amerikanske power-equipment projekt var den første tegning stærk på functional intent, men svag på production release. Den viste en 10-core pass-through wire harness, men panel thickness, cable OD tolerance, molded body durometer, latch direction og test access var ikke låst. Fordi projektet også havde Custom mold development required og Custom connector design, behandlede vi RFQ'en som et tooling-risk review, ikke som en simpel cut-crimp-assemble quote.
Vores første gate var at splitte designet i 5 kontrollerbare zoner: conductor preparation, terminal or splice area, molded transition, panel interface og external bend zone. For hver zone bad vi om målinger eller beslutninger: wire OD range for all 10 cores, minimum strip length, target molded OD, panel opening tolerance, allowed protrusion on both sides of the wall, service bend direction and whether the harness should be replaceable after installation. Den gennemgang ændrede quote-spørgsmålet fra “kan I lave denne?” til “hvilke data mangler før vi kan frigive tooling?”
Resultatet var, at projektet gik ind i active quotation and engineering review phase med en klar liste over tooling assumptions. Det er den rigtige rækkefølge for custom pass-through work: define measurable interface first, then cut prototype samples, then machine or print soft tooling, then approve production mold only after electrical, mechanical and dimensional evidence are aligned.
— Hommer Zhao, Grundlegger & CEO: I 10-core projektet var det afgørende spørgsmål ikke antal ledninger. Det var om custom connector, molded body og panel interface kunne frigives med samme drawing revision og samme testplan.
Design data du skal låse før prototype
Panel interface og installation envelope
Send panel material, wall thickness, hole shape, mounting direction, clearance, mating side, service side and allowed protrusion. Hvis pass-through delen skal installeres blindt, skal latch, keying eller orientation feature være tydelig. Hvis cable skal passere gennem en sharp-edged metal panel, bør drawing vise edge radius eller sleeve/grommet protection. For heavy-duty equipment wire harness skal mud, vibration, washdown og field replacement vurderes før geometry freeze.
Wire stack, OD og conductor routing
Angiv wire gauge, insulation type, OD range, color, twist, shield, drain and bundle diameter. En 10-core assembly kan virke enkel på schematic, men mold fill og bend behavior afhænger af hvordan cores ligger i overgangszonen. Hvis to larger conductors presses to one side, kan molded wall thickness blive ujævn. Hvis shield drain eller twisted pair ændrer lay length inde i molden, kan test performance ændres efter molding.
Mold material og jacket compatibility
Materiale skal vælges efter cable jacket, service temperature, chemical exposure, flexibility and sealing target. TPE, TPU, PVC og silicone-lignende elastomerer opfører sig forskelligt i adhesion, durometer og strain relief. RFQ'en bør bede supplieren skrive material family, hardness range, color, flammability requirement, expected shrink and whether primer or preheat is required. Hvis materialet kun står som “black rubber,” er specificationen ikke klar til production release.
Testplan før production mold release
En pass-through harness skal testes elektrisk før og efter den mekaniske proces, fordi molding, potting eller grommet compression kan flytte wires, skade insulation eller ændre strain relief. Minimum er 100% continuity, open/short and pinout validation. For power circuits bør resistance limit beregnes efter conductor length and gauge. For shielded eller signal circuits kan shield continuity, insulation resistance eller hipot være relevant, men test voltage, duration and leakage limit skal skrives i drawing eller control plan.
Mechanical release bør indeholde pull test, bend check and visual inspection. Et praktisk first article packet kan have 5 samples: 3 for dimensional and electrical release, 1 for destructive section review and 1 retained reference sample. Hvis customer requirement er strengere, følger du den. Section review er især nyttig for custom molded transitions, fordi den viser voids, off-center wire stack, insufficient wall thickness and jacket adhesion. For wire harness testing skal reporten gemme drawing revision, fixture ID, test-program revision, operator, date and pass/fail record.
Change control skal være defineret før første batch. Ændring af wire supplier, jacket material, mold material, colorant, terminal, panel thickness, cavity geometry or test method kan ændre performance uden at ændre part name. For IATF 16949-style programs bør disse ændringer trigge engineering review, first article update and customer approval where required.
— Hommer Zhao, Grundlegger & CEO: Jeg vil hellere skære én molded sample op i FAI end opdage 300 dele senere, at wire stacken ligger 2 mm off-center ved panel seal.
RFQ-checkliste for custom pass-through harness
Send en komplet RFQ-pakke: harness drawing, wire list, connector or terminal datasheets, 3D model, panel cutout, wall thickness, cable OD range, target IP rating if any, operating temperature, chemicals, UV exposure, vibration, expected annual volume, prototype quantity, production batch size, packaging constraints and service replacement requirements. Fortæl også om supplieren må foreslå alternate connector, alternate wire or alternate mold material.
Bed quote svare med tooling cost, sample cost, production unit cost, mold material, estimated cycle time, lead time, inspection plan, test method and assumptions. For low-volume or early design builds bør quote også adskille soft-tool prototype from production mold. Det gør det lettere at ændre panel latch, bend exit or body length efter fit check uden at skrotte production tooling.
Interne links i RFQ'en kan hjælpe engineering og purchasing med at tale samme sprog. Brug prototype wire harness til tidlige fit checks, crimping capability til terminal release, og wire harness testing til fixture and report requirements. Når disse tre områder er defineret, bliver custom mold work langt mere forudsigeligt.
FAQ
Q: What is a custom pass-through wire harness?
A custom pass-through wire harness is an assembly that routes conductors through a panel, wall or enclosure while controlling retention, sealing and strain relief. In the case above, the design used a 10-core pass-through wire harness with custom connector and mold requirements.
Q: When should I choose custom molding instead of a standard cable gland?
Choose custom molding when the envelope, connector shape, latch, bend direction or sealing surface cannot be handled by a standard gland. If a standard gland meets cable OD, wall thickness, pull load and service access, it often reduces tooling risk.
Q: What standards should appear in a pass-through harness specification?
Use IPC-A-620 for harness workmanship, UL-758 for wire construction and rating control, and IATF 16949 for traceability and change control when automotive-style launch discipline is required. Add IEC 60529 only when an IP sealing target is tested with time and depth.
Q: What data does a supplier need before quoting custom mold development?
Send 3D envelope, panel thickness, cable OD range, wire list, material target, annual volume, prototype quantity, pull-load requirement and test plan. For a 10-core harness, wire placement and molded wall thickness should be reviewed before production tooling.
Q: How do you validate molded strain relief?
Validate molded strain relief with dimensional inspection, bend check, pull test and electrical retest after molding. A first article packet with 5 samples can include 1 destructive section review when voids or off-center wire stack are a risk.
Q: Can a custom molded pass-through harness be waterproof?
Yes, but only when sealing is specified and tested. Define target rating, sample size, method, water depth or pressure, duration and electrical retest. “Waterproof” alone is not enough for production release.
Vil du reviewe et pass-through harness før tooling?
NorKab kan gennemgå panel interface, wire list, cable OD, custom connector concept, mold material, pull-load target, sealing plan and electrical test before prototype or production tooling. Kontakt NorKab med drawing, 3D model, expected volume and installation constraints, så hjælper vi med en praktisk releaseplan for dit custom pass-through wire harness.
