Precisely Controlling The Curing Cycle Of Epoxy Resin Tubing: Key Technical Points For Improving Insulation Performance

In the production process of electrical insulation components, the quality of epoxy bushing directly depends on the physicochemical reactions during the thermosetting process. Mastering the key timing points and temperature curves is fundamental for every technician to achieve high-quality output.

Preheating Phase Time Control Logic

The initial mold heating process determines the material's flowability. Before the epoxy resin tubing is injected into the mold, the mold must maintain a constant temperature. The preheating time should be dynamically adjusted according to the wall thickness to prevent internal stress accumulation due to uneven heating. Logically, preheating is not only for evaporating trace amounts of moisture but also to ensure that the subsequently injected resin is in an ideal wetting state.

Stepped time parameters of the curing reaction

The core curing period is the stage that determines the electrical strength of epoxy resin bushing. The curing process is divided into the following stages using a segmented temperature control method:

• Gel stage: At this stage, the resin transitions from a liquid state to an elastoplastic state.

• Initial curing period: The cross-linking reaction releases heat violently, and the duration must be strictly controlled to prevent explosive polymerization.

• Post-curing period: This stage often takes the longest.

The Impact of Post-Cure Time on Molecular Chain Reorganization

After initial molding, extending the post-curing time promotes full reorganization of the resin molecular chains. This is typically achieved at 130°C to 150°C for 4 to 8 hours. This process significantly increases the glass transition temperature of the epoxy resin sleeve, enhancing its mechanical support under extreme conditions.

Cooling Rate Management

The cooling rate of the finished product is also part of the process parameters. Sudden cooling can easily induce microcracks, which are difficult to detect with the naked eye but can severely damage the partial discharge properties of epoxy resin cast bushing. Setting a scientific cooling rate, allowing the product to cool slowly in the furnace, helps to offset residual thermal stress from the molding process.