What is the bonding process for the iron core?

The core bonding process is a crucial step in transformer manufacturing, primarily aimed at enhancing the mechanical strength of the core, preventing the separation ofindividual laminations, and ensuring long-term stable performance. Especially in the post-annealing treatment of the core, the bonding process effectively enhances the structural integrity of the core and improves itsmagnetic properties. The detailed steps of the core bonding process are as follows:

Concrete Step

●Selection of Bonding Varnish

In the core bonding process, 110-type epoxy solvent-free varnish is typically chosen. This varnish has excellent insulation properties and mechanical strength, making it suitable for core bonding. The 110-type epoxy solvent-free varnish consists of two parts:Component A and Component B, accounting for 35% and 65%, respectively. Before use, these two components must be thoroughly mixed to ensure the varnish's performance and adhesion.

●Impregnation Process

● Vacuum Extraction: Place the core in an impregnation tank and perform an initial vacuum extraction. This process lasts for 1 hour, ensuring that the tank pressure is reduced to 1×10^-3 Pa. The purpose of this step is to remove bubbles from within and on the surface of the core, improving the penetration effect of the bonding varnish.

● Immersion in Varnish: After completing the vacuum extraction, inject the epoxy solvent-free varnish into the tank until the core is completely submerged. At this point, stop the vacuum extraction to allow the varnish to fully penetrate every part of the core.

● Second Vacuum Extraction: Perform another 40-minute vacuum extraction, reducing the tank pressure to 8×10^-4 Pa. This further removes bubbles from the varnish, ensuring uniform impregnation of the core.

● Atmospheric Impregnation: After releasing the vacuum, let the core impregnate in the atmosphere for 20 minutes to allow the varnish to fully contact the core surface.

● Pressurization: Pressurize to 40×10^4 Pa and maintain it for 30 minutes to ensure that the varnish penetrates all gaps in the core under high pressure.

●Draining and Drying

Draining: After releasing the pressure, allow the core to drain varnish in a static state for 30 minutes to remove excess varnish further.

Natural Air Drying: Remove the core and place it on a rack to naturally drip and air dry for 3 hours.

Oven Drying: Place the core in an oven, first drying it at 120°C for 7 hours, then at 160°C for 8 hours. This process ensures the varnish is fully cured, achieving optimal bonding performance for the core.

●Post-Treatment

● Cleaning Varnish Accumulations: After drying, inspect the core surface and remove any accumulated varnish lumps to ensure a smooth final product surface without unnecessary varnish build-up.

In summary

By following these detailed bonding process steps, the core can be ensured to have sufficient mechanical strength and stability during use, thereby enhancing the overall performance and reliability of the transformer.

Contact Us

LuShan, est.1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single phase and three phase isolation transformers, electrical transformer, distribution transformer, step down and step up transformer, low voltage transformer, high voltage transformer, control transformer, toroidal transformer, R-core transformer; DC inductors, AC reactors, line and load reactor, chokes, filtering reactor, and intermediate, high-frequency products. Our power transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering(furnace), central air conditioning.

Know more about power transformer and reactor :www.lstransformer.com