Blister packaging · Industry glossary
Thermoforming
Shaping a heat-softened plastic web into blister cavities.
Also called: thermoformed blister; hot forming.
What is thermoformed in a blister machine?
The forming web is heated so that it can be shaped into cavities. Product filling and application of the lidding material are later operations. Thermoforming describes cavity production; it does not mean the lid is already sealed or that the product itself is moulded.
The forming material is a specified web or laminate, not an interchangeable generic plastic. Suitable conditions depend on its construction and the equipment. General forming guidance does not replace the specification and demonstrated operating range for that combination.
Why does cavity shape matter to barrier performance?
Forming redistributes a flat web into a three-dimensional pocket. Wall, corner and base thickness can differ from the original web thickness and from one another. Assess local thickness with the cavity geometry and material construction, rather than using the flat-web value as the complete formed-wall description.
The formed thickness distribution and barrier performance need assessment for the intended material, cavity and process. Nominal roll thickness and depth do not describe them, and forming-tool geometry must suit that combination.
Does a well-shaped pocket prove the blister is sealed?
No. Forming creates the pocket; sealing joins the lid to the forming material. The contact layer and lidding system still need to be compatible. A cavity that has the intended outline is not, by that observation alone, evidence of seal integrity or finished-package transmission.
For a material change, distinguish three questions in the supplier evidence: can the intended cavity be formed, can the proposed lid be joined to that structure, and what performance was measured on the resulting pack? Each requires its own stated object and conditions.
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