Assembling a wire terminal harness requires adherence to standardized procedures, covering material preparation, terminal crimping, wire insertion, locking verification, and protective treatments. Below is a step-by-step breakdown:
I. Material Preparation & Inspection
Wire Selection
Choose conductors (copper/aluminum), insulation types (PVC/XLPE), and gauge sizes based on electrical requirements (voltage, current, temperature).
Example: Automotive harnesses often use XLPE-insulated wires for high-temperature resistance, while industrial equipment may require flexible silicone wires.
Terminal & Connector Matching
Verify terminal types (e.g., plug-in, screw-clamp, spring-loaded) align with connector housing specifications.
Inspect crimping zones for deformation and ensure connector locking mechanisms (e.g., secondary locks) function properly.
Tooling Setup
Prepare wire strippers (1–2 cm strip length), crimping pliers (matched to terminal specs), multimeters (for continuity testing), and positioning fixtures.
II. Terminal Crimping
Wire Stripping
Use strippers to remove insulation, exposing the conductor without damaging strands.
Example: Strip 10 mm for terminals requiring a 10 mm crimping zone.
Crimping Process
Pull-out force must meet specifications (e.g., ≥10 kgf for AWG 22 wires).
Cross-section inspection: No cracks/burrs; conductor-terminal contact area ≥80%.
III. Wire Insertion into Connectors
Alignment & Guidance
Identify connector cavity shapes, depths, and alignment slots to determine insertion direction.
Example: Waterproof connectors require checking seal positions to avoid damaging seals during insertion.
Insertion Steps
Step 1: Insert the crimped terminal straight into the cavity. Avoid tilting to prevent poor contact.
Step 2: Listen for a distinct “click” indicating primary locking.
Step 3: Perform a gentle pull test (≤5 N) to confirm no terminal backout.
Secondary Locking (If Required)
Activate secondary locking mechanisms (e.g., TPA clips) using tools to prevent accidental disconnection.
Example: Automotive connectors often use TPA (Terminal Position Assurance) clips for enhanced reliability.
IV. Protection & Testing
Insulation Treatment
Bundling & Fixation
Continuity Testing
Use a multimeter to verify no open circuits, short circuits, or miswiring.
Example: Check each terminal pair for continuity (≤0.1 Ω resistance).
