Cap Sealing with Induction Heating

Applications Database

Access helpful pdf Application Notes after a brief registration:
Sealing aluminum foil cap to plastic bottle
Cap Sealing 3.5” Lotion Container
Tamper-evident cap sealing
Cap sealing; shampoo container

Overview

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

Using Induction

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.

Using Induction

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

When the aluminium foil is placed within the induction coil, the magnetic field, an electrical current develops within the foil, which is heated by the material's resistance to this current