Industrial Equipment
Sample Reverse Engineering → DFM → Production
Reverse-Engineered in 24 Hours, Improved Before Production:
Multi-Branch JST Wire Harness for an Industrial Controller
A client shipped us a reference sample with one request: replicate it, but make it better. Here is how we reverse-engineered the harness, identified two manufacturing risks, and delivered an optimized version — without a single drawing from the client.
24h
Reverse engineering complete
2
DFM issues caught before production
620mm
Trunk length, confirmed from sample
0
Rework units on delivery
01
The Client’s Situation
A manufacturer of industrial control equipment came to us with a wire harness they had been buying from a local supplier. The supplier had become unreliable — lead times were slipping, quality was inconsistent, and there was no documentation to support incoming inspection.
The client’s request was straightforward: take this sample, understand it completely, and produce a consistent, documented version we can rely on for ongoing production.
What they shipped us was a multi-branch wire harness with a black PVC jacket trunk, white JST-style connectors on three branch ends, printed sleeve labels on each branch, and a total trunk length of approximately 600mm.
💬
“Our current supplier cannot give us consistent quality or reliable lead times. We need someone who can document exactly what this harness is and produce it the same way every time.”
02
Reverse Engineering the Sample
Within 24 hours of receiving the sample, our engineering team produced a complete measurement and specification report. Every dimension, material, and connector parameter was captured and documented — creating for the first time a formal record of what this harness actually is.
| Component |
Measured from Sample |
Production Specification |
| Main trunk |
Black PVC jacket, ~620mm overall length |
620mm ±10mm, UL-listed PVC, 60°C rated |
| Wire gauge |
Estimated AWG 22 (power), AWG 26 (signal) |
Confirmed by cross-section measurement; documented in BOM |
| Connectors |
White JST-style, 2.0mm pitch, 2–3 position |
JST PH series specified; crimp terminal grade confirmed |
| Branch layout |
3 branches from single trunk breakout point |
Branch lengths individually measured and documented |
| Wire labeling |
Printed sleeve labels on each branch |
Retained and standardized; label content documented |
| Strain relief |
Cable tie at branch junction |
Upgraded — see DFM section below |
03
DFM: Two Issues We Found and Fixed
Reverse engineering is not just measurement — it is engineering review. When we examined the original sample closely, we identified two design features that were creating production risk and long-term reliability concerns. We flagged both to the client before production started.
A
Inconsistent branch breakout lengths
The original sample had branch lengths that varied by up to 15mm from unit to unit — a sign that the previous supplier was cutting by hand without a jig. In the client’s device, the harness routes to fixed PCB connectors with limited slack. A 15mm variation means some units fit and some do not — explaining the “inconsistent quality” the client had experienced. We specified fixed branch lengths with ±5mm tolerance and introduced a forming board into our process to hold this consistently across every unit.
B
Unprotected branch junction under vibration
The original design used a single cable tie at the branch breakout point. In a static installation this is acceptable, but industrial controllers experience vibration from motors, fans, and mechanical handling. A single cable tie allows the junction to flex repeatedly, which fatigues the wire insulation at the point of highest stress concentration. We replaced the cable tie with a short section of adhesive-lined heat shrink over the junction — providing mechanical support, abrasion protection, and a cleaner finish, at negligible added cost.
Both changes were presented to the client in a one-page DFM report before production started. The client approved both immediately.
04
What Drives the Cost of This Harness
Because we were replacing an existing supplier, cost transparency was important. We provided a full BOM alongside our unit price so the client could compare component for component — not just headline number to headline number.
①
JST PH connector & terminals
Genuine JST PH series specified. Terminal crimp quality is the most common failure point in this connector family — we use calibrated tooling and verify crimp height on every first-article run.
②
UL-listed wire
AWG 22 for power conductors, AWG 26 for signal. UL listing ensures consistent insulation thickness, temperature rating, and flammability grade — variables that are often substituted in low-cost production.
③
Forming board assembly
A custom forming board holds all branch lengths to specification during assembly. This adds a small setup cost but eliminates the dimensional variation that caused the client’s original quality problems.
④
100% electrical testing
Every unit tested for continuity and correct connector polarity before shipment. Test records retained for traceability. No sampling — 100% inspection on every batch.
05
Production Process
With the specification locked and the DFM changes approved, production followed a documented process that could be repeated identically on every subsequent batch — which was exactly what the client needed after years of inconsistent supply.
Wire cutting to fixed lengths
All wires cut using a programmable wire cutter to ±2mm accuracy. No hand-cutting. Branch lengths fixed per the forming board specification.
Sleeve label application
Printed identification sleeves applied before crimping — not after. This ensures labels are permanently positioned and cannot shift during connector insertion.
JST terminal crimping & insertion
Crimp terminals applied with calibrated tooling. Crimp height measured on first-article units. Terminals inserted into JST housing and retention-force checked.
Branch forming & junction sealing
Harness laid on forming board and branches routed to specified lengths. Adhesive-lined heat shrink applied at junction point and shrunk to seal.
Continuity & polarity testing
100% electrical testing on every unit. Results logged per batch for traceability. Any failure quarantined and root-cause documented before re-work.
Visual inspection & packaging
Final visual check against IPC/WHMA-A-620 Class 2 workmanship standard. Units individually bagged. Batch test report included with each shipment.
06
Delivery & Outcome
The first production batch of 100 units was delivered in 3 weeks from sample receipt. The client’s incoming inspection passed all units on first check — a result they had not seen from their previous supplier in over a year.
The two DFM improvements proved their value immediately: branch length consistency meant every unit fitted the device PCB without adjustment, and the heat-shrink junction held up cleanly through the client’s vibration acceptance test.
The client transitioned all ongoing production to WireAssyTech within 60 days of first delivery.
Sample to delivery
3 weeks
Incoming inspection pass rate
100%
DFM issues resolved
2 / 2
Production transferred
60 days
07
What to Know When Switching Wire Harness Suppliers
✓
A physical sample is enough to start
If you have a harness you are currently using — even one purchased from another supplier — that sample contains all the information needed to produce a formal specification. Ship it to us and we will document it completely within 24 hours.
✓
Inconsistent quality usually has a process cause
Random variation in a wire harness — lengths that sometimes fit and sometimes do not, connectors that occasionally mis-seat — is almost always the result of hand processes without fixtures. The fix is not more inspection; it is process control.
✓
Ask for a BOM and traceability records
A supplier who cannot provide a component-level BOM and batch test records is one who cannot consistently reproduce what they have built. These documents are the minimum requirement for any production-grade harness relationship.
✓
Supplier transitions do not have to be disruptive
A structured reverse-engineering handover — sample, specification, DFM review, first-article approval — can be completed in under four weeks without interrupting your existing production schedule.
Using a wire harness from another supplier?
Ship us a sample or send us photos. We will reverse-engineer it, document the full specification, identify any DFM risks, and give you a production quote — within 48 hours.
Send Us Your Sample →
Free DFM review · Full BOM provided · MOQ 50 pcs · IPC/WHMA-A-620 Certified
