High Frequency Induction Cap Sealing With IGBT heating units
Objective To heat an aluminum foil inside a plastic shampoo cap forĀ sealing Material 2.0ā diameter, plastic flip top cap, with a 0.9ā diameterĀ aluminum foil seal Temperature 250 – 300 ĀŗF (120 ā 150 Ā°C) Frequency 225 kHz Equipment DW-UHF-7.5 kW, induction heating system, equipped with aĀ remote heat station containing two 1.5 Ī¼F capacitors (totalĀ capacitance 0.75 Ī¼F). An induction heating coil designed and developed specificallyĀ for this application. Process A three-turn two-position helical coil is used to heat theĀ aluminum foil in a tunnel style assembly. Product (containers) passes easily under the induction coil. The assembly is locatedĀ such that the entire perimeter of the aluminum foil is heated uniformly. The container and cap is placed under the coil andĀ RF power delivered for 0.12 seconds. The aluminum foil heats and seals to the plastic of the cap. Results/Benefits This induction heating configuration fulfills the process requirements and: ā¢ uses a simple, economical coil design ā¢ increases throughput with a dual-position coil ā¢ delivers quality, consistent seals ā¢ offers a repeatable process, well-suited for automation
InductionĀ Heating Aluminum Foil For Cap Sealing with IGBT inductive heater
Objective An induction heater is used to heat a polymer laminatedĀ aluminum foil in 0.5 to 2.0 seconds. The heat produced in theĀ aluminum foil melts the polymer that bonds to the neck of aĀ plastic container. Material Aluminum foil, polyethylene, polypropylene, polyvinylchloride,Ā polystyrene, polyethylene terephthalate, styrene acrylonitrile Temperature 300 – 400 (ĀŗF), 149 – 204 (ĀŗC) Frequency 50 to 200 kHz Equipment DAWEIĀ solid-state induction powerĀ supplies operating between 1 & 10 kW at frequencies of 50-Ā 200 kHz. These units operate with remote sealing heads whichĀ allows the main power cabinet of the equipment to be locatedĀ away from the immediate production area. Distances of up toĀ 100 meters are possible. The microprocessor is used to control and protect the system and ensures that the optimal operatingĀ frequency is maintained at all times and that each container receives the same amount of heat energy from cycle to cycle. Process Two different types of aluminum foil laminates are available forĀ this application. The first assembly includes backing board/reseal, a wax layer, aluminum foil, and a heatseal filmĀ for supported systems (Figure 1). The second assemblyĀ includes a high temperature film, aluminum foil, and a heatsealĀ film for unsupported systems (Figure 2). The procedure is to fitĀ the foil membrane into the cap and to fit the cap to theĀ container after the product is filled. Results For the aluminum foil assembly as shown in Figure 1, heatĀ induced in the metallic foil by the induction coil almost instantaneously melts the polymer coating and the neck of theĀ container forming a hermetic seal between the heat seal film and the rim of the container. The heat also melts the waxĀ between the aluminum foil and the back board. The wax is absorbed into the back board. This results in an air tight bondĀ between the aluminum foil/membrane and the rim of the container, the back board is released and remains in the cap.
Process (contād) In the case of unsupported membranes in Figure 2, one side ofĀ the aluminum foil is coated with a heat sealable polymer filmĀ and this face that will be in contact with and sealed to theĀ container. The other side of the foil that will be in contact withĀ the cap has a higher melting-point film that prevents adhesionĀ of the aluminum to the cap allowing the end user to unscrewĀ the cap. Unsupported membranes are typically used where theĀ end user pierces the tamper evident membrane prior toĀ dispensing the product.Ā The aluminum foil acts as a vapor barrier preserving theĀ freshness of the product and prevents it from drying.
