Complete Wire Harness Manufacturing Process: 12 Steps from Design to Delivery

Every wire harness that leaves our factory floor goes through at least 12 distinct manufacturing steps. Miss one, rush another, and you've got a harness that might pass initial testing but fails in the field. After producing millions of harnesses, I can tell you: the process matters as much as the design.

This guide walks through our complete wire harness and cable assembly manufacturing process. Whether you're an engineer specifying harnesses, a purchasing manager evaluating suppliers, or just curious about how these critical components are made—this is what actually happens.

1Design Review & DFM Analysis

Every project starts with our design engineering team reviewing your specifications. This isn't a rubber-stamp process—we're looking for potential issues before they become production problems.

What We Review:

• Connector compatibility: Do the specified terminals match the wire gauge? Will the housing accommodate the number of circuits?
• Wire routing feasibility: Can the harness be built on our assembly boards? Are bend radii achievable?
• Material availability: Are all components in stock or readily available? What are lead times?
• Testing requirements: What electrical and mechanical tests are needed? Do we have the capability?

This DFM (Design for Manufacturing) step catches approximately 30% of potential issues before production starts. It's free for quoted projects, and we provide detailed feedback within 24-48 hours.

2Material Procurement & Kitting

Our global sourcing team procures all materials from approved suppliers. We maintain relationships with authorized distributors for major connector brands—Molex, JST, TE Connectivity, Amphenol, Deutsch, and others.

Materials are kitted in our warehouse before production starts. Each work order gets a dedicated kit containing exact quantities of wire, terminals, connectors, and accessories. This eliminates line-side shortages and ensures traceability.

3Work Order Creation & Traveler Documentation

Every harness is built against a detailed work order that travels with the product through production. This traveler includes:

• Full assembly drawing with dimensions and callouts
• Bill of materials with part numbers and quantities
• Step-by-step work instructions
• Quality checkpoints and inspection criteria
• Test specifications and acceptance criteria

For automotive and medical harnesses, the traveler also captures operator signatures, lot numbers, and any process deviations. This documentation is retained for 10+ years per IATF 16949 and ISO 13485 requirements.

4Wire Cutting & Stripping

Cutting and stripping is the first hands-on production step. Our automatic cut-and-strip machines handle wire from 32 AWG to 2 AWG, processing thousands of wire segments per hour with ±0.5mm length tolerance.

Key Parameters:

For specialty wires—high-temperature, shielded, or multi-conductor—we use semi-automatic or manual stripping with custom blade sets to prevent damage.

5Terminal Crimping

Crimping is where most harness failures originate—and where proper process control makes the difference. We operate 50+ crimping stations with tooling for virtually every terminal type.

Our Crimping Process:

1. Applicator setup: Tooling configured for specific terminal/wire combination
2. First-piece inspection: Cross-section and crimp height verification before production
3. Production crimping: Automatic or semi-automatic depending on volume
4. Crimp force monitoring: Real-time verification on critical applications
5. Pull-force testing: Sample testing per IPC-620 requirements

Critical insight: Crimp height alone doesn't guarantee quality. We perform cross-section analysis on setup pieces to verify the wire strands are properly compacted within the crimp barrel. This is especially important for fine-stranded and high-flex wires.

6Soldering Operations

Not every harness requires soldering, but when it does, proper technique is critical. Common soldering applications include:

• PCB terminations (through-hole and surface mount)
• Cup terminals and turret connections
• Shield terminations and ground braids
• Splice joints (when crimping isn't practical)
• Component integration (resistors, capacitors, LEDs)

Our operators are IPC-certified for hand soldering. For high-volume production, we use selective soldering and reflow processes to ensure consistency.

7Harness Assembly

This is where individual wires become a harness. Assembly happens on form boards—large fixtures that hold the harness in its final shape during construction.

Assembly Steps:

1. Terminal insertion: Pre-crimped wires are inserted into connector housings per the assembly drawing
2. Wire routing: Wires are laid out following the form board path
3. Bundling: Wire bundles are secured with tape, ties, or sleeving
4. Connector seating: All connectors verified for proper terminal seating (TPA/CPA where applicable)
5. Breakout positioning: Branch points secured at specified locations

For complex automotive harnesses, a single harness might pass through 15-20 stations, with different operators handling different sections.

8Secondary Operations

Beyond basic assembly, many harnesses require additional processing:

9Overmolding & Potting

For waterproof cable assemblies and harsh environment applications, overmolding and potting provide the ultimate protection.

Overmolding:

Thermoplastic material (typically TPE, TPU, or PVC) is injection-molded around the connector interface, creating a sealed, strain-relieved connection. We operate 8 injection molding machines for in-house overmolding capability.

Potting:

For electronics encapsulation, we use epoxy or polyurethane potting compounds. This protects sensitive components from moisture, vibration, and thermal cycling.

10Electrical Testing

Every harness receives 100% electrical testing. This isn't optional—it's how we ensure zero defects leave our facility.

Standard Test Suite:

For automotive and medical applications, additional environmental testing may include temperature cycling, vibration, and salt spray exposure.

11Visual Inspection & Quality Audit

After electrical testing, every harness receives visual inspection against IPC/WHMA-A-620 workmanship standards. Inspectors check:

• Connector and terminal condition
• Wire routing and bundling quality
• Label placement and readability
• Solder joint quality (where applicable)
• Overall cleanliness and appearance
• Dimensional conformance to drawing

Rejected harnesses are tagged, segregated, and either reworked or scrapped depending on the defect severity. We maintain detailed records of all rejections for continuous improvement analysis.

12Packaging & Shipping

Proper packaging protects your investment during transit. We customize packaging based on product requirements:

• Individual poly bags: Standard for most harnesses, with part number labels
• Anti-static bags: For ESD-sensitive assemblies
• Coiled and banded: Long harnesses wound to prevent tangling
• Custom trays: For delicate or complex geometries
• Reusable racks: For kanban delivery programs

Our inventory management system supports various fulfillment models including stock-and-release, consignment, and JIT delivery.

Why Process Matters

You can have a perfect design and premium materials, but without disciplined manufacturing processes, quality is inconsistent. Every step in our 12-step process has been refined over thousands of production runs and millions of harnesses.

Whether you need rapid prototypes or production quantities, the process remains the same. The only difference is scale—and we've engineered our facilities to handle everything from one-off samples to hundreds of thousands per month.