Sealing Problems Checklist For Blisters & Blister Cards

Also available in PDF format.

Determine nature of the sealing difficulty
1. What is the strength of the seal?
  1. Does the blister fall off the card?
  2. Does the blister only pull ink off the card?
  3. Does the blister pull some board fiber from the card?
2. Are the blister card and blister compatible?
  1. What is the type of blister material?
  2. What is the type of adhesive coating used on the card?
  3. How old are the blister cards being used?
Evaluate sealing equipment condition and settings.
1. What is the temperature of the sealing platen?
  1. Platen temperature should be between 290°F and 340°F. Start low and go higher if needed. Use surface thermometer on platen to insure accuracy.
2. What is the interface temperature?
  1. The interface temperature is the temperature achieved between the blister flange and the blister card during the heat seal process.
  2. Interface temperature should be between 190 o F and 230 o F. Start low and go higher if needed.
3. What is the dwell time (amount of time the platen is in direct contact with the blister card)?
  1. Dwell time should be between 2 to 4 seconds. Start low and go higher if needed.
4. What is the air line pressure to the equipment?
  1. The heat sealer must receive adequate pressure. We recommend approximately 100 pounds line pressure - see manufacturer's manual for recommendations and limitations.
5. Is the heated platen in good condition?
  1. The platen should be perfectly flush or parallel to the sealing fixture to allow uniform pressure to be exerted around the perimeter of the sealing fixture.
  2. All platen heating elements should be checked to insure full and proper operation.
Evaluate sealing fixture condition and placement.
1. Sealing fixture should be positioned close enough to the bottom surface of the heated platen, prior to activation, to obtain maximum pressure in down stroke. (see manufacturer's manual for recommendations)
2. The sealing fixture should be perfectly flush or parallel to the heated platen to allow for uniform pressure to be exerted around the perimeter of the sealing fixture.
3. The sealing fixture should be constructed of durable materials and supported such that it will not flex or bow during the sealing process.
4. Gas release channels may need to be incorporated into the sealing fixture to allow for quick release of moist, heated air created by the heat seal process.
5. The gasket material (coroprene, silicone rubber, etc.) on the sealing fixture should be in good condition.
6. Sealing cavity should not be so tight as to prevent the blister flange from easily resting on the sealing fixture gasket material.
For additional information and assistance
1. Contact your Andex Account Representative
2. Contact your equipment manufacturer.