Chilly Willy
The “Chilly Willy” Story
Westpak™ always considers the specific needs of the client, and often times, can create a specialized fixture or piece of equipment to accommodate the test parameters required by a client.
Take for example, the “Chilly Willy” story. Our client produced and sold ice cream to various stores nationwide. For the most part, the distribution environment kindly favored the product…that is until one main hazard came into play. The culprit was high altitude. The ice cream had no issues travelling the states at normal elevation. However, as soon as the transport trucks carried the product up the hills at high elevation, the containers began to expand, and ice cream started to ooze out the sides. This was certainly a “sticky” situation. Luckily, Westpak™ is always glad to help and willing to take on new challenges.
A test needed to be developed in order to accurately and efficiently simulate the environment in which the ice cream was spilling out of the containers. Three factors were considered in this test plan: The air temperature surrounding the ice cream, the vibration from the transport vehicle, and of course, the high altitude. To simulate these conditions, Westpak™ created a transparent cylindrical container constructed from acrylic. A Thermal Kinetic Systems Chiller and pressure transducer were integrated with the equipment to control air pressure. A temperature controller and chart recorder were also integrated with the chamber. This chamber could now control both temperature and altitude at the same time.
Our client was able to bring their ice cream to Westpak™ and place their product inside the “Chilly Willy” chamber. The chamber was then placed on top of a vibration machine, and the test was ready to begin. The distribution environment could now be created in the laboratory. The Client was able to save a lot of time and money by simulating as many runs as necessary to troubleshoot their problem and finally discover the proper ice cream formulation that would not expand due to the higher elevation. “Chilly Willy” is just one of the many examples where the packaging expertise of Westpak™ helped solve a client’s need.
-Elit Doubrava
Test Engineer
Specs used for this case study:
The Chilly Willy story is an illustration of combined environment testing. There isn’t any one standard that put all of these tests together, but rather use several methods combined to create damage known to occur in the field. Westpak has a great amount of knowledge in the area of combined environment testing. The combination of specifications used in this particular case study are:
- ASTM D4332
- ASTM D4728
- ASTM D6653
More is better....right?
A Common Misconception
When protecting a package system from vibration hazards seen in the distribution environment, is adding more foam always better? If your answer to this question is no, then you are one of the few who can be proud of getting the answer right! Adding excessive amounts of foam to cushion a product is a common misconception that can lead to many field failures. It is not necessarily better to just add more foam. The correct way to design a package system is to design the cushion so that it can attenuate the vibration input at those frequencies where the product is most sensitive.
Westpak™ will not only test your package system, but can also offer useful recommendations to help solve packaging issues. Here is one example:
Westpak™ had a client that tested a product on a floating deck inside a crate. The crate utilized 3 inch thick polyethylene foam as the cushioning medium. In order to determine whether this was a successful cushion design, Westpak™ conducted a product and package vibration test.
The purpose of this test was to determine the natural frequency of the spring mass system consisting of the cushion material (spring) when loaded with a product (mass). The desired performance characteristic of the package system is to have a natural frequency one octave below the lowest product critical frequency determined in the initial product vibration test.
The results of the package test revealed that the foam was not properly designed; the package resonance was similar to the product’s resonant frequency. This amplified the resonance of the product at the critical frequency. Westpak™ recommended modifying the cushion material under the floating deck of the package system in order to alter the resonance characteristics of the package. The cushion material was removed in small increments until the proper vibration characteristics were achieved. The removal of material increased the “loading” (weight/area) on the cushion in order to drive the package resonance down to a level of half the structural resonance of the product. That is exactly what the data showed when the package system was retested. The cushion was able to attenuate or filter the vibration input at the product’s resonant frequencies. Less foam was better.
-Elit Doubrava
Test Engineer
Specs used for this case study:
- ASTM D1596
- ASTM D3580
- ASTM D4728
