LM2000 Aluminum Foil Induction Sealing Machine Full Automatic Can Sealing Machine Biscuits and Candy Sealing Machines

Induction sealing is often described as “non-contact heating,” but what actually happens inside the cap? Understanding the process helps operators set the machine correctly and troubleshoot sealing defects. The LM2000 uses an induction sealing head to generate an alternating electromagnetic field. When a bottle with an aluminum foil liner passes under the head, the foil generates eddy currents and heats up. The heat melts the heat-seal coating on the liner, and the coating bonds to the bottle mouth. After the bottle leaves the induction field, the foil cools and the bond solidifies. The result is a hermetic foil seal attached to the bottle mouth.

The capped bottle moves along the conveyor and passes under the induction sealing head. The head does not touch the cap. The distance between the head and the cap affects the strength of the electromagnetic field at the foil. If the bottle is too low or too high, the field may be weak or uneven. The lifting device on the LM2000 allows the head to be adjusted to the correct height for the bottle.

The alternating current in the induction head creates a changing magnetic field. This field induces eddy currents in the aluminum foil liner. The foil has low electrical resistance, so the eddy currents generate heat quickly. The bottle material and the cap are not directly heated because they are not conductive in the same way. This is why induction sealing can heat the foil without heating the entire bottle.

The aluminum foil liner usually has a heat-seal coating on the side facing the bottle mouth. When the foil heats up, the coating melts and presses against the bottle mouth. The cap torque and the liner structure provide the contact pressure. The melted coating flows into the microscopic surface of the bottle mouth and forms a bond. The quality of this bond depends on temperature, time under the induction head, pressure, and bottle mouth cleanliness.

After the bottle leaves the induction field, the foil cools. The melted coating solidifies and creates a sealed layer. The foil remains bonded to the bottle mouth. When the consumer opens the cap, the foil should stay on the bottle mouth, providing visible tamper evidence. If the foil stays inside the cap, the bond may be too weak, or the liner release layer may be incorrect.

Power setting, conveyor speed, induction head distance, bottle mouth diameter, liner structure, cap torque, and bottle mouth cleanliness all affect the final seal. A larger bottle mouth may need more energy or lower speed. A thicker liner may need more heat. A dirty bottle mouth may prevent bonding even at the correct power. The LM2000 allows power and speed adjustment, but the operator must confirm the settings with the actual bottle and liner.

Weak seal: check power, speed, head distance, cap torque, and bottle mouth cleanliness. Burned foil: reduce power or increase speed; check liner compatibility. Foil stays in cap: check liner release layer and sealing pressure. Uneven seal: check head alignment and bottle stability. These checks help operators solve common problems before calling for service.

Does the induction head touch the cap?
No. Induction sealing is a non-contact process. The head generates an electromagnetic field, and the foil heats inside the cap.

Why does the foil heat but not the bottle?
The aluminum foil is conductive and responds to the electromagnetic field. Plastic and glass are not heated directly.

How long does the seal take?
The heating time is very short and depends on line speed and power. The foil cools quickly after leaving the induction field.

Can the machine seal through a thick cap?
The cap must be non-metallic and the liner must be positioned correctly. Very thick or metallic caps may interfere with the field.

What causes a weak seal?
Common causes include low power, high speed, incorrect head distance, weak cap torque, and bottle mouth residue.