Epoxy Vacuum Casting Process | Insulation Potting Technology & Equipment Solutions

Epoxy vacuum casting is an advanced manufacturing technology for insulating materials, widely applied in power transmission and transformation equipment, electronic components and composite material industries. This process performs resin casting under negative pressure to effectively eliminate air bubbles inside materials, greatly improving products’ electrical insulation performance, mechanical strength and surface finish.

Core Technology & Advantages

Epoxy vacuum casting upgrades traditional atmospheric-pressure molding to vacuum molding, which facilitates complete bubble removal from casting compounds and drastically enhances the internal and surface quality of finished products. Its primary advantages are listed below:

• Excellent electrical performance: Minimal or zero air gaps deliver high volume resistivity, greatly boosting insulation and voltage withstand capacity, making it ideal for high-voltage equipment.

• Compact & miniaturized structure: Superior fluidity enables one-time molding of complex geometries, optimizing equipment structure and supporting product miniaturization.

• High protection rating: Fully encapsulated construction completely blocks moisture and corrosive gas, reaching IP68 protection grade with outstanding waterproof, anti-corrosion and explosion-proof performance for harsh working conditions.

• Safe & weather-resistant: Solid, flame-retardant formulation with superior weatherability, suitable for indoor and outdoor installation and realizing lifelong maintenance-free operation.

Typical Application Fields

This technology is extensively adopted in industrial scenarios with strict requirements for insulation, protection and reliability:

1. Power Transmission & Transformation: Dry-type transformers, instrument transformers, high-voltage bus ducts (covering 10kV–35kV and DC 1500V systems), insulating accessories for megavolt power transmission equipment, etc.

2. New Energy & Special Industries: DC side current collection for photovoltaic inverters, battery cluster connection in energy storage power stations, DC power transmission for wind power converters, high-current electrolysis production, power distribution for highly corrosive chemical environments.

3. Electronics & Automotive Components: TV flyback transformers, automotive ignition coils, sensors, microelectronic devices, battery modules and motor winding potting.

4. Composite Material Manufacturing: Vacuum infusion molding for high-performance composites including wind turbine blades, marine parts, sports equipment and construction formworks, with glass fiber content exceeding 70%.

Technological Process & Quality Control

The epoxy vacuum casting process features rigorous procedures, including raw material pretreatment (vacuum drying), mixing, pre-curing, demolding, post-curing and post-processing. Strict control over the following critical links is mandatory to guarantee product quality:

• Temperature matching: Mold temperature shall be around 10℃ higher than casting compound temperature to avoid sink marks; slow cooling after post-curing relieves internal stress and prevents cracking.

• Raw material cleanliness: Strict incoming material inspection and dust-free production environment to avoid impurity inclusion; static mixing casting equipment is recommended.

• Defect prevention: Optimize mold vent design, extend mixing duration and conduct surface pretreatment for embedded inserts to eliminate surface defects such as air holes, shrinkage cavities and cracks.

At present, epoxy vacuum casting equipment has achieved intelligent operation, with mature material systems and formulas. Domestic equipment and materials are fully capable of meeting the technical standards for ultra-high voltage power transmission equipment.