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Suitable for semi-automatic or automatic production, easy use, easy set up. Install by place over the current conveyor without modification. Use space over the conveyor less than 50 cm.
Induction Process of a Two-Piece Seal
Pressure - Heat - Time (PHT)
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 all areas of the land area of the container. 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. On the closure and container - the shape of the threads. The number of threads per inch. 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 and the skirt of the closure will not bottom out on the shoulder of the container. This is the 'H'dimension of the container closure. If the land area of the container has any defects, such as high spots (at seems) or possible low areas, (saddle), you will have uneven pressure. When you induction seal a liner to the container, and if there is not enough pressure on the liner and land areas, the following could happen: Leakers 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: One or all of the above could happen at once. It is very important that the toirquing heads be checked at least once a shift to ensure that each closure receives its proper “on-torque". It is possible to over-torque a closure and when this happens it could strip the threads and give uneven pressure. It's important that rigidity of the closure is strong enough so as to not distort when torque onto a container.
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 job. It is a good idea to have one of the suppliers or manufacturers of induction seal equipment run trials at the facility. They will recommend what is needed. The size of the induction seal equipment is very important; it must have the capacity and power to efficiently produce the field and heat around the induction liner to seal under your conditions of line speed.
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.
Large containers that are hot dilled require the proper length of time under the sealing head. More important is the time needed after sealing - e.g. If the container is hot filled at 200°F and you are using a polypropylene induction liner, the induction coil can heat the liner and the land area of the container to approximately 400°F. It is very hard to determine what temperature the liner sees. The induction seal liner starts sealing to the land area after it cools down to approximately 270°F. This is why time is needed after sealing to allow cool down and in that time, the container must not be bumped, banged or roughly handled because, if it is, the seal can be broken and you may experience leakers as a result of the air hammer effect.
Remember that when you hot fill a plastic bottle it changes its shape and the larger the container the more it expands; also, the hotter the fill the easier it is to change the shape of the container. When a one gallon container is hot filled and is roughly handled, the air hammer effect on the seal to the land area can be disturbed, causing lack of adhesion. HEAT SINK The container acts as a heat sink. This means that when you induction seal the liner with sufficient pressure to the land area, the container absorbs heat from the induction seal liner. When you do not have sufficient liner pressure and/or uneven pressure against the land area, poor seals will result. Because of the overheating of the liner, the land area could have suffered a lot of meltdown which in turn causes more uneven pressure. For example, if the induction seal liner, by itself, has been passed through the induction coil, it could reach a high temperature of 600°F or more thus causing the liner to melt or possibly burn. It makes some difference if the container is full or empty - hot filled or cold filled. Normally a higher power setting is required for a cold fill that a hot fill. The same is true if the container is full rather than empty. If you have overhang of the liner or tabs are folded down the side of the container, this will causes some problems with induction sealing. The induction field does not react to aluminum foil that is in a vertical position when passing under the induction head. In some cases with the tabs folded down, the induction field gets deflected so the liner in that area sees less heat. Round corners on the tab tend to deflect less than square corners on tabs. If you have a large portion of the liner folded over the edge of the container, this will have a cooling effect on the part of the liner that is on the land area and will produce weak seals or leakers