Lightweighting in Can Manufacturing
What is Lightweighting?
Lightweighting involves reducing the amount of aluminum in a can to the optimal level, ensuring the container meets mechanical properties required for filling and handling. Achieving this balance is critical for maintaining product integrity while minimizing material costs.
As Lluis explains, “You cannot reduce just to reduce; the can must meet mechanical properties. The fillers need a container that won’t cause problems.”
As Lluis explains, “You cannot reduce just to reduce; the can must meet mechanical properties. The fillers need a container that won’t cause problems.”
Historical Perspective on Can Weights
Forty years ago, cans weighed around 19 grams for a 211 x 413 format (Lid and Body). Today, advancements in materials and processes have reduced some cans to less than 12 grams (again, Lid and Body), with ongoing developments pushing weights even lower. However, each reduction brings increased challenges.
Pre-Work Before Lightweighting
Before starting a lightweighting project, it is important to optimizing current processes:
Optimize the Current Line:
Ensure that the line is running efficiently. Address issues like high tear-off rates, spoilage, or inconsistent can properties. Collaboration with tooling suppliers, OEMs, and engineering companies is crucial to stabilize the operation before introducing lightweighting.
Review Tooling and Drawings:
Check if existing tools align with the desired can specifications. Older tooling designs or outdated drawings from the 1970s may not meet today’s tight tolerances or support modern lightweighting needs.
Ensure Consistency in Materials:
Advances in materials and coatings—such as those for punches and clamp rings—allow for more precise and efficient lightweighting. These innovations must be incorporated into the tooling strategy.
Optimize the Current Line:
Ensure that the line is running efficiently. Address issues like high tear-off rates, spoilage, or inconsistent can properties. Collaboration with tooling suppliers, OEMs, and engineering companies is crucial to stabilize the operation before introducing lightweighting.
Review Tooling and Drawings:
Check if existing tools align with the desired can specifications. Older tooling designs or outdated drawings from the 1970s may not meet today’s tight tolerances or support modern lightweighting needs.
Ensure Consistency in Materials:
Advances in materials and coatings—such as those for punches and clamp rings—allow for more precise and efficient lightweighting. These innovations must be incorporated into the tooling strategy.
Lightweighting Challenges and Key Considerations
Window of Runability:
Lightweighting narrows the operational tolerance. For example, variations in top wall thickness that are acceptable with thicker gauges become critical with thinner gauges, potentially leading to issues in the Necker.
Match Gap Optimization:
In the Cupper, the gap between the OD of the Die Center and the ID of the Blank and Draw Die must be optimized. A gap that’s too tight hardens the aluminum, while a gap that’s too loose creates wrinkles, both of which can cause problems in the Bodymaker.
Progression in the Bodymaker:
Lightweighting requires careful adjustment of the progression chart for ironing dies. The percentage of reduction, especially at the third ironing die, must be precise to avoid tear-offs and ensure uniform top wall thickness.
Rework Taper on the Punch:
The geometry of the punch, particularly the Rework Taper, must align with the reduced gauge. Incorrect taper geometry can lead to excess material at the bottom of the can, resulting in unnecessary weight added to the can.
Lightweighting narrows the operational tolerance. For example, variations in top wall thickness that are acceptable with thicker gauges become critical with thinner gauges, potentially leading to issues in the Necker.
Match Gap Optimization:
In the Cupper, the gap between the OD of the Die Center and the ID of the Blank and Draw Die must be optimized. A gap that’s too tight hardens the aluminum, while a gap that’s too loose creates wrinkles, both of which can cause problems in the Bodymaker.
Progression in the Bodymaker:
Lightweighting requires careful adjustment of the progression chart for ironing dies. The percentage of reduction, especially at the third ironing die, must be precise to avoid tear-offs and ensure uniform top wall thickness.
Rework Taper on the Punch:
The geometry of the punch, particularly the Rework Taper, must align with the reduced gauge. Incorrect taper geometry can lead to excess material at the bottom of the can, resulting in unnecessary weight added to the can.
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