There are many opportunities today that exist in reducing a containers weight, often referred to as “light weighting”. The challenge lies in designing a container along with the tooling that allows for weight reduction, without sacrificing the containers aesthetic appeal, top load requirement, impact performance and stability. Industry experts have dedicated a significant amount of time to mold engineering design and researching “light weighting”.
For the past 10-15 years blow molders have worked to reduce container weight with the traditional standard designs that include dairy, juice and water. The request to reduce has been expanded to industrial applications such as bleach, detergents, and industrial solvents to name a few. When taking on a project, gram weight is one of the main factors to consider.
When working with a customer to reduce weight in a container, taking a methodical approach is best, starting with establishing a baseline of an existing design or a new proposed design. The baseline would consist of starting with current weight and recording the critical data relative to volume, top load, drop impact, wall mapping of the entire container, head tooling design and failure points arrived at by performing a destruct test. If the container is new there are a couple of avenues to pursue. One is utilizing FEA (Finite Element Analysis) capability. This helps identify weak or problem areas of interest that would include structural performance. Heat transfer also needs to be reviewed based on fluid flow to achieve the best cooling potential of the mold.
Once the data is accumulated engineering will need to research previous documentation to apply the proven attributes that were involved with successful reduction designs. These will typically consist of radius, angles, ribs, and texturing to cover the main ones. If the bottle has a handle there are handle designs that are proven to be robust, comfortable and have a blow ratio to make the bottle process friendly.
Much of the data is recorded based on the results accumulated in the lab where the testing is done. An efficient lab department should consist of the latest equipment required, to include top load tester, drop impact chamber, top wave vision system, vibration stand, Magna Mike and altitude chamber. These tools help in determining the next steps in the process to yield the best design.
ROI can be quickly calculated by taking the gram weight savings per container and multiplying this by the number of containers ran over a one week period. Converting the total grams into pounds, then multiplying by resin cost will give you the weekly savings.
Example: Production of 240,000 one gallon bottles a week with a 7 gram savings can save close to $3,000 USD per week and $78,000 USD for a 6 month period. New tooling can typically be justified in less than one year depending on the bottle production, size, and the opportunity to make changes.
Milacron has extensive experience and knowledge in light weighting, often reducing the weights on dairy designs up to 17% with a series of changes to radius, modified vertical angles in the top and aesthetic ribs that flow with the shape. We have basically stayed with the same conceptual design due to the strength it has displayed for many years. We have fine-tuned the critical areas of the bottle to increase the strength, which in turn allows us to reduce the weight. Milacron’s Uniloy product brand has decades of experience and a state of the art testing laboratory in Tecumseh, Michigan for customer testing.
To learn more about weight reduction in blow molded containers and how Milacron can help, please visit our website here.