Cap Sealing with Induction Heating

The food and medical industries require high-speed hermetic sealing between the cap and the container. Induction heating with Ameritherm equipment provides the following benefits for cap sealing applications:

• high reliability seals
• easy integration into production lines
• high process speeds

A cap- to-container seal is made with the aid of a laminated disc composed of a wax layer, aluminum layer, and a polyethylene (PE) layer (illustration).
The aluminum layer acts as a susceptor, heating to about 125-150°C in the electromagnetic field produced by the induction coil. It then heats the wax and PE layer sufficiently to produce a hermetic seal between the cap and container. Heating times are in the order of 100 milliseconds, supporting a high-speed automated process.

Typical RF power supplies for cap sealing range from 1 to 20 kW, depending on the parts and application requirements.

A cap seal liner is comprised of a multi-layered board:

• the first and thickest layer of material is the board re-seal

• next is the layer of wax used to hold the aluminium foil to the board re-seal

• next is the aluminium foil

• last is a heat seal film compatible with the type of container to be sealed