EV Charger Production Line and Factory Setup

Inputs we need before designing anything

• Product variants, including power levels, connector types and enclosure options
• Annual volume for the first three years, by variant
• Shift model and available working days
• Target local content level, which determines how much is assembled versus received
• PCBA build or buy decision
• Target cycle time, or the constraint that sets it
• Available floor area, power supply and environmental conditions

Volume forecasts are always uncertain. What matters is the ratio between the low and high case, because that determines whether the line should be manual and flexible or fixtured and fast.

Process flow

1. 1

   Incoming quality control

   Verify parts against specification and reject before they enter stock. Critical components need certificate checks, not just count checks.

2. 2

   Subassembly

   Harness preparation, module preassembly, anything that can be built off the main line to protect takt.

3. 3

   Final assembly

   Mechanical build, harness routing, torque controlled fastening, sealing.

4. 4

   Firmware programming

   Firmware, configuration and identity applied at a controlled station.

5. 5

   End-of-line test

   Full functional and safety relevant sequence with recorded results.

6. 6

   Final inspection

   Workmanship and cosmetic verification against defined criteria.

7. 7

   Burn-in where specified

   Applied when the product or customer requires it, sized against takt.

8. 8

   Packing and despatch

   Per packing specification, with traceability retained.

Line layout

Layout decides material flow, and material flow decides whether the line can be audited. The design separates ESD zones, isolates high voltage test from general assembly, and gives work in progress, rework and quarantine physically distinct locations.

• Single direction material flow, with no crossing of good and rejected stock
• ESD protected area covering all board handling stations
• High voltage test physically separated with interlocked access
• Defined work in progress buffers sized to the bottleneck
• Rework station with its own tooling and its own records
• Quarantine that cannot be casually re-entered into stock

Station tooling

Every measuring or torque applying tool needs a calibration interval and an owner. A torque driver with no calibration record makes the entire build record unverifiable.

Capacity model

The capacity model connects volume to staffing and equipment. It covers cycle time per station, takt derived from demand and available time, staffing per shift, parallel stations where a step exceeds takt, the identified bottleneck, an overall equipment effectiveness assumption and the buffer sizing that protects rate.

State the OEE assumption explicitly. A line planned at theoretical throughput will miss its number, and the gap gets blamed on operators rather than on the plan.

Quality gates

• Incoming: sampling against defined criteria, with reaction plan for failures
• In process: torque verification, crimp pull testing, visual checkpoints
• End of line: full sequence, pass required to proceed
• Audit sampling: periodic deeper test on units that already passed
• Traceability: every unit linked to its parts, process records and test results

Pilot and ramp

1. 1

   Engineering build

   Small quantity built by engineering to validate the process and the documentation.

2. 2

   Controlled pilot

   Built by production operators, with engineering present, at low rate.

3. 3

   Rate trial

   Demonstrate the line can hold takt and yield over a sustained run.

4. 4

   Start of production

   Released against defined criteria, not against a calendar date.

5. 5

   Stabilization

   Monitored window where yield, defect Pareto and early field data are reviewed jointly.

Training matrix and factory readiness

Every station has a defined competence requirement, and every operator has a record of which stations they are signed off on. Unsigned operators do not run stations. This is the control that makes yield data meaningful.

Before the first production shipment, a factory readiness audit checks documentation control, calibration status, training records, ESD compliance, traceability, and the physical separation of good, rework and quarantined stock.