A wire harness may look simple in its final form — a bundle of wires, connectors, and protective components — but the manufacturing process behind it involves multiple carefully orchestrated stages. Each stage must be executed with precision to ensure the finished assembly performs reliably in its intended application. This article walks you through the complete wire harness manufacturing process, from initial design through final delivery, with a detailed look at how SIMKAB approaches each phase.
Stage 1: Requirements Gathering and Engineering Review
Every wire harness project begins with understanding the customer’s requirements. This includes reviewing electrical schematics, connection diagrams, and specifications for the target application. Engineers evaluate factors such as operating voltage and current, environmental conditions (temperature, moisture, vibration), connector types and pin configurations, wire gauges and insulation materials, regulatory and certification requirements, and physical routing constraints within the final assembly.
At SIMKAB, this is the first step of our 4-step process: Understand. Our engineering team works directly with the customer to ensure every technical requirement is captured and clarified before any design work begins. We ask detailed questions, review reference documents, and identify potential issues early — saving time and cost downstream.
Stage 2: Wire Harness Design and Documentation
With requirements defined, the design phase begins. Engineers create detailed wire harness drawings that specify every component, dimension, and routing path. Modern wire harness design typically uses specialized CAD software to produce 2D schematic drawings, harness layout drawings with exact dimensions and branch lengths, connector pinout tables, and a complete Bill of Materials (BOM) listing every wire, connector, terminal, sleeve, label, and accessory.
The BOM is a critical output of this phase. It drives procurement, production planning, and cost estimation. A well-prepared BOM ensures that all materials are sourced correctly and available before production begins.
At SIMKAB, this is our second step: Design. Our engineers translate your requirements into manufacturable wire harness designs, optimizing for performance, cost, and producibility. We deliver complete documentation packages that leave no ambiguity on the production floor.
Stage 3: Prototyping and Design Validation
Before committing to serial production, most wire harness projects go through a prototyping phase. Prototype wire harnesses are built in small quantities — often just one to five units — and provided to the customer for fit, form, and function testing. Prototyping allows both the manufacturer and customer to verify that the harness fits within the target assembly, all electrical connections function correctly, the design can be manufactured efficiently, and there are no interference or routing issues in the real-world installation.
Any issues discovered during prototyping are addressed through design revisions before moving to full production. This iterative approach prevents costly errors during high-volume manufacturing runs.
Stage 4: Material Procurement and Production Planning
Once the design is validated, the procurement team sources all materials according to the BOM. This includes ordering wire in the correct gauges and insulation types, connectors and terminals from approved suppliers, protective materials such as conduit, braided sleeving, heat shrink tubing, and labels and identification markers. Lead times for specialized components can vary significantly, so experienced manufacturers plan procurement well in advance and maintain strategic inventory of commonly used materials.
Stage 5: Wire Cutting and Preparation
Production begins with wire cutting. Automated wire cutting machines cut each wire to its specified length with high accuracy. Depending on the design, wires may also be stripped (insulation removed from the ends) and marked with identification labels or printed codes at this stage. Precision in cutting and stripping is essential — a wire cut too short cannot be used, while inconsistent strip lengths can cause quality issues during termination.
Stage 6: Termination — Crimping and Soldering
Termination is the process of attaching terminals or contacts to the ends of each wire. The most common method is crimping, where a metal terminal is mechanically compressed onto the stripped wire end using a crimping tool or press. Crimp quality is monitored through crimp height measurements, pull force testing, and visual inspection per IPC/WHMA-A-620 standards. For applications requiring soldered connections, trained operators perform soldering according to established workmanship standards, ensuring proper wetting, fillet formation, and joint integrity.
Stage 7: Assembly on Harness Boards
With all wires terminated, the assembly phase begins. Operators route the wires onto dedicated assembly boards (also called jig boards or form boards) that replicate the exact layout of the finished harness. Assembly boards have pins, guides, and connector holders positioned to match the harness drawing. Operators follow standardized work instructions to route each wire along its designated path, insert terminals into connector housings, apply bundling materials such as tape, cable ties, or conduit, and install any additional components like grommets, clips, or mounting brackets.
At SIMKAB, stages 3 through 7 represent our third step: Produce. Our production floor is equipped with dedicated assembly boards for each harness design, ensuring consistency and repeatability across every unit we build. Operators follow detailed visual work instructions, and in-process quality checks are performed throughout the assembly sequence.
Stage 8: Testing and Quality Control
Every completed wire harness undergoes rigorous testing before it is approved for shipment. Standard tests include electrical continuity testing to verify that every circuit is connected correctly, insulation resistance and hi-pot testing to confirm there are no shorts or insulation breakdowns, and visual inspection against IPC/WHMA-A-620 workmanship criteria. For customer-specific requirements, additional tests such as pull force testing on crimps, dimensional verification, or functional testing may be performed. Test results are documented and linked to each harness for full traceability.
Stage 9: Packaging and Delivery
The final stage is packaging the tested wire harnesses for safe transport to the customer. Packaging methods depend on the size, fragility, and quantity of the harnesses. Common approaches include individual bagging with desiccant for moisture protection, custom cardboard dividers to prevent tangling, foam inserts for delicate connector assemblies, and clear labeling with part numbers, revision levels, and lot codes. Proper packaging ensures that the harness arrives at the customer’s facility in the same condition it left the factory.
At SIMKAB, this is our fourth and final step: Deliver. We coordinate logistics to meet your delivery schedule, whether you need a single prototype shipment or recurring serial production deliveries. Every shipment includes full documentation — test reports, material certificates, and packing lists — so you have complete visibility into what you are receiving.
SIMKAB’s 4-Step Process: Understand, Design, Produce, Deliver
At SIMKAB, we have distilled the complex wire harness manufacturing process into a clear 4-step framework that keeps every project organized and on track. From the initial requirements review through final delivery, our team maintains transparent communication and rigorous quality control at every stage. This structured approach allows us to consistently deliver wire harness assemblies that meet our customers’ exact specifications, on time and within budget.
Want to see how SIMKAB’s manufacturing process can bring your wire harness design to life? Request a quote today and let our team guide you from concept to finished product.
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