MCCB Key Parts Production:

Core Process Overview

The production of MCCB (Molded Case Circuit Breaker) parts must meet the requirementsof high precision, high stability, and high weather resistance. Below is a breakdown ofthe production focus for 5 categories of core parts.

1.Operating Mechanism Parts (Handle, Connecting Rod.Latch)

2. Tripping System Parts (Bimetallic strip, Coil,Transformer

3.Arc-Extinguishing Device Parts (Arc-ExtinguishingChamber, Arc Grid)

4.Contact System Parts (Moving/Fixed Contacts)

5. Housing and Terminal Blocks

1.Operating Mechanism Parts (Handle, Connecting Rod Latch)

(1) Material Selection

• Handle: Flame-retardant PA66 + glass fiber (temperature resistance ≥120℃, UV-resistant);

• Connecting Rod/Latch: Cold-rolled steel plate (needs galvanization) or zinc alloy (die-cast molding).

(2) Core Processes

• Handle: Injection molding (precision ±0.05mm) → Sandblasting for anti-slip → Laser marking;

• Connecting Rod/Latch:

◦ Steel plate type: Stamping → CNC finishing → Galvanization;

◦ Zinc alloy type: Die casting → Deburring → Passivation.

(3) Quality Inspection Focus

• Handle: No cracks after 1.5m drop test, UL94 V-0 flame retardancy;

• Connecting Rod/Latch: No deformation under 500N tension, dimensional sampling rate ≥10%.

2. Tripping System Parts (Bimetallic Strip, Coil,Transformer)

(1) Bimetallic Strip (Overload Protection)

• Material: Three-layer composite metal (total thickness 0.8-1.2mm);

• Processes: Rolling (precision ±0.01mm) → Laser cutting → Annealing (350-400℃);

• Quality Inspection: Under 1.5 times rated current, bending deviation ≤0.1mm within 1 hour.

(2) Electromagnetic Coil (Short-Circuit Protection)

• Material: Enamelled copper wire (temperature resistance ≥155℃), PBT framework;

• Processes: Framework injection molding → Automatic winding (turn error ≤1%) → Varnish dipping and curing;

• Quality Inspection: Insulation resistance ≥100MΩ, no breakdown in 1500V AC inter-turn withstand voltage test.

(3) Leakage Transformer (Optional)

• Material: Silicon steel sheet core (high magnetic permeability), thin enamelled copper wire;

• Processes: Core lamination → Toroidal winding (2000-5000 turns) → Epoxy resin potting;

• Quality Inspection: Transformation ratio error ≤±5%, output signal ≥100mV under 30mA leakage current.

3. Arc-Extinguishing Device Parts (Arc-Extinguishing Chamber, Arc Grid)

(1) Arc-Extinguishing Chamber

• Material: Ceramic (temperature resistance ≥1200℃) or arc-resistant plastic (arc resistance index ≥180s);

• Processes:

◦ Ceramic type: Dry pressing → High-temperature sintering → Precision grinding;

◦ Plastic type: Injection molding → Deburring → Arc-resistant treatment;

• Quality Inspection: No breakdown under 10kA short-circuit current, no damage under 5J impact.

(2) Arc Grid

• Material: Cold-rolled silicon steel sheet (thickness 0.35-0.5mm);

• Processes: Stamping (spacing error ±0.05mm) → Nickel plating → Automatic stacking;

• Quality Inspection: Arc grid spacing 0.5-1mm, contact resistance ≤50mΩ.

4. Contact System Parts (Moving/Fixed Contacts)

• Material: Silver alloy (silver content ≥85%, anti-welding) + T2 red copper base material;

• Processes: Composite rolling → Stamping → Resistance welding → Surface polishing;

• Quality Inspection: Contact resistance ≤10mΩ, no welding under 10 times rated current.

5. Housing and Terminal Blocks

(1) Housing

• Material: Flame-retardant ABS+PC alloy (UL94 V-0, temperature resistance -30℃~100℃);

• Processes: Injection molding → Matte spraying → Screen printing for markings;

• Quality Inspection: No breakdown in 1500V AC insulation test, self-extinguishing time ≤10s in vertical burning test.

(2) Terminal Blocks

• Material: H62 brass (tin-plated, anti-oxidation);

• Processes: Cold heading → Tapping (precision 6H) → Chamfering;

• Quality Inspection: When clamping 2.5mm² wire, no loosening under 100N tension, no deformation after baking at 100℃.

Core Production Standards and Trends

1. Comply with IEC 60947-2 and GB 10963.1; key items require third-party testing (e.g., SGS, TÜV);

2. Automation rate of core processes (winding, stamping) ≥80% to reduce manual errors;

3. Meet RoHS 2.0 environmental requirements, waste recycling rate ≥90%.

What Kind Of Service Can We Provide?

A good supplier will assist you to quickly occupy the target market, gain a goodreputation for your brand and reputation, and thus gain more stability and better benefits.

OEM Service

Customized Logo printing or laser for authorized trademarks
Customized authorized trademarkpackaging (outer box, inner box)
Customizable catalogue of authorized trademarks
Available for small quantity order
Your overseas super factory

ODM Service

Product mold design anddevelopment
Product function design and development
Product international test reports &Certificates
24-hours response
Your overseas super factory

Factory Service

200+ workers, Fast delivery
Automated production lines
Certified lS0 90001 system
Acquired CB, CE, TUV, BV, SAA, CCC,FCC product certificates
15+ sales and customer service staff,Fast responsiveness
Extra long warranty, 5 years warranty