Note: Sealing an aluminum disk onto a plastic cap

Objective:

Seal an aluminum disk onto a plastic cap at a rate of 90 per minute for an application in the bottling industry 

End Product:

Bottle cap

Equipment:

  • Ambrell EKOHEAT 30 kW, 50 to 150 kHz induction heating system equipped with a remote heat station containing six 1.0 μF capacitors.
  • A single position, one turn 12” helical coil designed and developed for this application.

Materials:

  • Plastic cap (top and bottom) with an outside diameter of 1.85” (47 mm)
  • Aluminum disk with an outside diameter of 0.8” (20 mm) 

Temperature:

300 ºF (149 ºC)

Frequency:

80 kHz

Testing:

The aluminum disk was placed into the top cap and the bottom cap was threaded onto the top. The cap was then placed 1/8” (3.2 mm) away from the coil. The EKOHEAT was turned on and the cap heated to the target temperature in three seconds. This process resulted in a strong bond between the plastic and the aluminum. With the 12” (305 mm) coil that can heat multiple caps at the same time and a heating time of three
seconds, the targeted production rate of 90 caps per minute can be achieved and exceeded. 

Benefits:

  • Precise heating: Induction heating enabled the aluminum to seal to the plastic cap quickly without the cap being damaged.

  • Speed: The customer desired a quick rate which would make in-sourcing the process worthwhile, and induction heating exceeded the targeted production rate thanks to its fast heating.

  • Clean and flameless heating: Given the plastic cap, clean, flameless heating was required to maintain its integrity. 

Sealing an aluminum disk onto a plastic cap

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