As a core equipment for ship electrification, the manufacturing process of electric outboard motors must balance lightweight design, water resistance, and power stability. The entire process covers four modules: raw material selection, core component processing, integrated assembly, and performance testing, with each link complying with strict marine equipment standards.

1. Raw Material Selection and Pretreatment

1.1 Core Material Selection

The housing uses 6061 aluminum alloy plates (tensile strength ≥ 290MPa), balancing lightweight properties and seawater corrosion resistance; the motor housing adopts die-cast aluminum ADC12 (silicon content 9.5%-12%), enabling one-time molding of complex structures through die-casting; the drive shaft uses 304 stainless steel (chromium content ≥ 18%) to prevent rust in salt spray environments.

Electrical components must meet IP67 or higher protection class: the controller's PCB board uses FR-4 temperature-resistant substrate (temperature resistance ≥ 130℃), and the wire harness adopts neoprene insulation layer (oil-resistant and seawater-immersion resistant).

1.2 Pretreatment Process

Aluminum alloy plates are degreased and descaled in a 5% sodium hydroxide solution (soaked at 40℃ for 10 minutes) to remove oxide layers, then undergo phosphating treatment (zinc-based phosphating solution, film thickness 5-8μm) to improve subsequent coating adhesion; the stainless steel drive shaft undergoes quenching and tempering (quenching at 860℃ + tempering at 550℃) to reach a hardness of HRC28-32, ensuring torsional resistance.

2. Precision Processing of Core Components

2.1 Housing Processing

Die-Casting Molding: A cold-chamber die-casting machine (clamping force ≥ 8000kN) is used to inject molten ADC12 aluminum liquid (temperature 650-680℃) into the mold, forming the housing blank (dimensional tolerance ±0.5mm) while reserving motor mounting holes and drive system relief grooves.

CNC Precision Milling: A 5-axis machining center (positioning accuracy ±0.005mm) is used for milling the housing's joint surfaces and mounting holes. The diameter tolerance of motor mounting holes is controlled to H7 (+0.015/-0mm), and the fit clearance between the drive shaft hole and bearing is maintained at 0.008-0.012mm to ensure component assembly coaxiality.

Surface Anti-Corrosion Treatment: The outer surface of the housing undergoes hard anodization (anodic oxide film thickness 15-20μm, hardness ≥ HV300), and the inner wall is coated with epoxy resin (dry film thickness 60-80μm). Corrosion resistance is verified through a salt spray test (no rust after 500 hours).

2.2 Motor Component Processing

Stator Processing: Silicon steel sheets (35W250) are stamped into stator cores using a high-speed punch press (punching frequency ≥ 600 times/minute), with the lamination factor controlled above 0.95; an automatic winding machine (winding alignment accuracy ±0.1mm) is used to wind copper wire windings. After winding, vacuum impregnation with epoxy resin paint (baking at 120℃ for 4 hours) is performed to improve insulation performance (withstand voltage ≥ 1500V).

Rotor Processing: The rotor shaft is processed using a CNC lathe (spindle speed ≥ 6000rpm), with the journal roundness ≤ 0.003mm; the rotor core and shaft adopt an interference fit (interference amount 0.02-0.03mm). After press-fitting, a dynamic balance test is conducted (balance accuracy Grade G2.5, residual unbalance ≤ 5g·mm) to avoid vibration during high-speed operation.

2.3 Drive System Processing

Gear Processing: Reduction gears are made of 20CrMnTi alloy steel. After hobbing on a gear hobbing machine (module 2-3, gear tooth accuracy Grade 6), fine finishing is performed on a gear shaving machine (tooth surface roughness Ra ≤ 0.8μm); the gears undergo carburizing and quenching (carburized layer depth 0.8-1.2mm, surface hardness HRC58-62) to ensure wear resistance.

Clutch Assembly: Clutch friction plates are made of copper-based powder metallurgy materials (density ≥ 6.8g/cm³). After hot pressing (temperature 850℃, pressure 30MPa), they are riveted with stainless steel pressure plates, with the assembly clearance controlled at 0.15-0.2mm to ensure smooth power transmission.

3. Control System Integration and Waterproof Treatment

Controller Assembly: The PCB board is soldered with chips, capacitors, and other components using the SMT (Surface Mount Technology) process (mounting accuracy ±0.05mm), followed by through-hole component soldering via wave soldering; the controller housing is injection-molded from ABS engineering plastic, and the interior is filled with epoxy resin potting compound (thermal conductivity ≥ 1.2W/(m·K)) to achieve both waterproof and heat dissipation functions.

Wire Harness Integration: Wire harness connectors use waterproof aviation plugs (IP68 protection class), with wires connected via ultrasonic welding (welding strength ≥ 50N); the wire harness is wrapped in corrugated tubes (temperature resistance -40℃ to 120℃) and fixed in pre-designed card slots inside the housing using cable ties to prevent abrasion caused by vibration.

4. Final Assembly and Multi-Dimensional Testing

4.1 Final Assembly Process

Step 1: Hoist the motor assembly into the housing, fix it with locating pins (tolerance H6/g5), and connect the motor shaft to the drive shaft via a coupling (coaxiality ≤ 0.02mm);

Step 2: Install the reduction gearbox, inject special gear oil (viscosity 150cSt at 40℃), and use nitrile rubber gaskets (compression rate 20%-30%) to ensure no oil leakage;

Step 3: Integrate the controller and control handle, connect the wire harness and test circuit continuity, and finally install the propeller (connected to the drive shaft via a keyway, fit clearance 0.01-0.02mm).

4.2 Performance Testing

Power Test: Simulate different loads (0-100% rated power) on a dynamometer, record rotational speed (error ≤ ±2%), torque (error ≤ ±3%), and battery life;

Waterproof Test: Immerse the entire machine in 1m deep water for 24 hours, then test insulation resistance (≥ 500MΩ) and circuit functionality after removal;

Vibration Test: Test on a vibration table (frequency 10-500Hz, acceleration 10g) for 2 hours, checking for no loose components or abnormal noise.

5. Quality Inspection and Delivery

Each electric outboard motor must pass appearance inspection (no scratches on the surface, uniform coating) and performance re-inspection (qualified power and waterproof performance), and be accompanied by an ex-factory inspection report; packaging uses moisture-proof cartons with foam cushioning and built-in anti-collision corners to ensure no component damage during transportation. The final product must comply with GB/T 38948-2020 "electric outboard Motors for Ships" before delivery to customers.