Induction Sealing - The Process
Pressure - Heat - Time (PHT)
The induction sealing is process of pressure-heat and time. The following will describe what the process is and what happens when an induction seal liner is sealed to the land area of the container. The induction seal liner must be applied to the land area of the container with even and uniform pressure to all areas of the land area. When the container is passed through the induction seal equipment, sufficient heat is produced to melt the sealing face of the liner and it bonds uniformly to the land area of the container mouth. The induction seal liner must spend a sufficient amount of time under the induction seal equipment and it must have sufficient time after sealing to cool down and form an aggressive bond.

IMPORTANCE OF P.H.T.
Pressure is needed for the liner to seal to the container and there are a number of factors that contribute to pressure.

1. On the closure and container - the shape of the threads.
2. The number of threads per inch.
3. The design of the neck and threads of the container must be matched to that of the closure so that the closure will give even pressure to the land area.
4. Poor land area of the container has any defects, such as high spots (at seems) or possible low areas, (saddle), you will have uneven pressure.

Due To Improper Pressure The Following May Result:

• Leakages · Melt down of land area
• The induction seal liner will be overheated, melted, destroyed. It could burn and produce an odor and or contaminate the product.
• There could be melting of the secondary liner.

Note: To ensure proper pressure make sure you design cap and bottle neck properly You need to have proper torque while capping - Do not over/under tight the caps

Heat is also a very important ingredient required to produce a strong seal of the liner to the container. The closeness of the induction sealing head to the foil in the liner is very important as is having the right induction head for the application.

Time is needed when the closure is passing under the induction coil. The induction seal liner needs sufficient time under the coil to be heated to the proper temperature for the sealing surface to melt and bond to the land area of the container. Also, the 'Two-piece" liner requires more time for the wax to be absorbed into the white lined pulp.