Deep Draw Container Forming Method for Blister Packs
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Solution Overview
Problem
Current methods for manufacturing blister packs face challenges in uniform material thickness and material fracturing due to uneven stress distribution, particularly when forming deep blisters with steep angled or vertical walls, and issues with delamination in metal-plastic foils when containing fluids.
Innovation Solution
The process involves using a first plunger to form a primary contour with a depth of at least 100% to 150% of the final recess depth, followed by a second plunger to reshape the film into the final recess shape, using a warm-forming process to relax residual stresses and prevent delamination, while maintaining the surface area formed in the first stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a single plunger is used to form deep blisters with steep angled or vertical walls, then the desired complex blister shapes can be achieved, but uneven stress distribution occurs leading to material fracturing and non-uniform thickness
Solution Approach 1:
The forming process is segmented into multiple stages with different plungers. A first plunger forms a preliminary contour with gentler slopes, and a second plunger then forms the final deep blister shape with steep walls. This segmentation allows each stage to handle specific geometric requirements without causing material failure.
Solution Approach 2:
The first plunger performs preliminary action by creating a pre-formed contour that prepares the material for the final forming stage. This preliminary shaping redistributes stress before the second plunger creates the final deep blister geometry, preventing fracturing during the critical forming process.
2Productivity
If conventional forming methods are used to create deep blisters, then the forming process can be completed, but material fracturing occurs due to concentrated stress
Solution Approach 1:
The forming operation is divided into multiple sequential steps using different plungers. The first plunger creates a preliminary shape that distributes stress evenly, and the second plunger completes the deep blister formation. This segmentation prevents stress concentration that would cause material fracturing.
Solution Approach 2:
The first plunger performs preliminary forming action to prepare the material by creating a pre-formed contour with redistributed stress patterns. This preliminary action strengthens the material structure before the second plunger applies the final forming forces, preventing fractures.
3Adaptability or versatility
If metal-plastic foils are used in blister formation, then the packaging functionality is achieved, but delamination occurs due to residual stresses from the forming process
Solution Approach 1:
The first plunger performs preliminary forming that creates a pre-formed contour with reduced residual stresses. By completing the major shaping action in the first stage, the second stage requires less force, minimizing stress-induced delamination in the metal-plastic laminate structure.
Solution Approach 2:
The forming process parameters are changed between stages - the first plunger uses parameters optimized for creating the preliminary contour, while the second plunger uses parameters optimized for final shaping. This parameter optimization reduces residual stresses that cause delamination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures even stress distribution, reduces the likelihood of fractures, and minimizes delamination, enabling the creation of complex blister shapes with improved uniformity and stability.
Implementation Method 1
using a warm-forming process to relax residual stresses and prevent delamination
Data Source
AI summary
The present disclosure is directed to processes for manufacturing shaped articles for unit-dose packaging with at least one formed recess (e.g., a blister), in particular for unit-dose packaging of pharmaceutical dosage forms. In certain embodiments, the first step of the process is directed to drawing the film material (e.g., metal-plastic foil) with one or more plungers to form a primary contour, the contour having a depth of at least 100% and up to 150% of the depth of the formed recess. The second stage involves shaping the primary contour with one or more plunger(s) to the desired formed recess, with a depth that is less than the depth of the primary contour, while substantially maintaining the surface area of the primary contour formed in the first stage. The formed recess may be formed using warm-forming or cold-forming techniques.