Wire Harness Manufacturing: From Drawing to Final Test

Wire harness manufacturing turns a controlled drawing and parts list into an assembly with the correct electrical connections and physical layout. The route usually includes wire preparation, termination, connector assembly, protection and testing. Choose equipment for those operations and the finished harness geometry; wire size alone does not define the production line.

Start with the finished harness

Before comparing machine speed, prepare a drawing showing connector orientation, cavity numbers, branch lengths, splice locations, labels and protective coverings. Identify the wire, terminal, seal and housing by their actual part references. Distinguish the finished length on the drawing from the wire cut length used by the machine.

Record the order mix as well as the total quantity: repeated identical leads, frequent connector changes and short batches create different tooling and handling needs. A machine can process the wire but still be unsuitable for the required connector loading or changeover pattern.

Build the route around each connection

Operation	What must be defined	Evidence to check before the next operation
Cut and strip	Wire construction, finished and cut lengths, strip geometry	Length and exposed conductor condition
Fit seals or identification	Correct part, position and assembly sequence	Part presence, orientation and position
Crimp terminals	Terminal presentation, matched crimp tooling and application settings	Visual condition and specified dimensional/mechanical checks
Insert terminals into housings	Cavity map, orientation and locking sequence	Seating and retention using the connector’s procedure
Route and protect the harness	Branch geometry, sleeves, tape positions and handling	Layout and protection against the assembly drawing
Test and release	Pinout, required electrical tests and acceptance limits	Recorded results linked to the assembly identity

The sequence is connector-specific. A sleeve or seal that cannot pass over a finished terminal must enter the route before that obstruction is created. Some connector systems use different sealing arrangements; do not apply a single-wire-seal process to every sealed housing.

For crimp setup, use the terminal’s application and tooling documents. Molex’s tooling guidance explains where to find strip length, crimp height and pull-force requirements. Those values belong to a defined connection, not to an AWG number in isolation.

Match the machine to the operations you need

For repeated leads with terminals on both ends, our WM-3202 cut-strip-crimp machine is a starting point for an AWG 18–28 shortlist. Housing insertion is a separate selection question.

For leads requiring wire seals at both ends, compare the WM-377 seal-and-crimp machine, specified for AWG 28–16. If the job also requires housing insertion at both ends, examine the WM-3247 integrated assembly machine, specified for 0.35–2 mm². We check the actual terminals, seals, housings and pinout before confirming the configuration.

Harness bundling is another operation. The WM-4105 spot-taping workstation is one option to trial when the bundle geometry and tape match its specification. It does not replace the drawing, branch fixture or finished-harness inspection.

Keep three quality decisions separate

• Crimp quality: Was the terminal formed correctly around the conductor? Use the specified visual, dimensional and mechanical checks.
• Connector assembly: Is each terminal in the correct cavity and securely retained? A sound crimp can still be incorrectly inserted.
• Electrical function: Does the assembly meet its required circuit tests? Passing continuity alone does not prove sealing or mechanical retention.

Our crimp inspection guide explains the different measurements. For a terminal that retreats when the connector is handled, use the terminal back-out diagnosis.

Compare accepted assemblies, not isolated cycles

For a sample trial, send the complete component set and the drawing revision. Agree which operations are included, what requires operator handling, and how setup, changeover, rejected parts and final inspection will be recorded. Compare output over that defined route rather than multiplying one short video cycle into an hourly promise.

Use our trial acceptance checklist to prepare the record. Send your harness drawing and samples and we will propose the process sequence and record the trial on your actual parts.