Epoxy Resin Sleeve On-site Casting: Curing Expansion Space Sealing Process

When handling the casting of epoxy bushing manufacturer bushings on-site, the most troublesome aspect is the volume change during the curing process. If the sealing process is not done properly, leakage or insulation defects can easily occur later. Today, we'll get straight to the point and discuss how to seal that crucial expansion space during on-site casting.

Initial sealing preparations for pouring

The on-site environment is complex, with temperature and humidity constantly changing. Before casting, the sealing interface at the bottom of the bushing must be thoroughly cleaned. At this point, the sealing material used must have good affinity with the resin. Many people are accustomed to using simple tape or foam to fill the gaps, but this cannot handle the internal pressure generated by the heat of curing. We recommend using a highly flexible composite sealing gasket, leaving a certain amount of extrusion allowance.

Expansion and plugging process

This step is the core of the entire process and directly affects the forming quality of the epoxy bushing for transformer sleeve. Specifically, this can be broken down into the following key operational points:

• Overflow channel setup: Leave a small venting and overflow hole at the highest point of the sealing structure, allowing excess resin to have a place to go during expansion.

• Segmented Injection Frequency: Controlling the height of each injection reduces instantaneous heat generation, allowing the bottom sealing layer to withstand the liquid column pressure.

• Pressure Balance Maintenance: Using physical clamps to fix the sealing mold prevents the internal stress during resin curing from pushing the sealing structure open.

Stress Release Monitoring During Curing:

The resin undergoes an exothermic peak as it changes from liquid to solid. The sealing site experiences the most intense compression during this stage. Experienced technicians often say that checking for resin seepage at the sealing opening indicates internal density. Maintaining the elastic support of the sealing structure allows the resin to find a balance between contraction and expansion. After the heat dissipates, the sealing structure should naturally conform to the sleeve wall.

Post-Current Finishing and Quality Inspection:

After curing, remove the temporary sealing components. Observe the junctions for air bubbles or shrinkage gaps. If burrs are found on the edges, they must be sanded smooth without damaging the structural integrity of the sleeve itself. Following this process significantly improves the reliability of on-site casting.