Author Question: Explain how to determine if a packaging material is appropriate for a particular delicate ... (Read 54 times)

Yi-Chen · **on:** Aug 19, 2018

Explain how to determine if a packaging material is appropriate for a particular delicate instrument.

What will be an ideal response?

Question 2

In an expansion molding operation, why does fusion occur in the mold and not in the pre-expansion step?

What will be an ideal response?

Dinolord · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

The vibrational characteristics, especially the natural vibrational frequencies, are determined for the material by sensing the forces transmitted through the material at various frequencies. The natural frequencies of the material and other frequencies at which high stresses are transmitted are then compared to the natural frequencies of the transportation system that will carry the package. If the frequencies of the transportation system match the natural frequencies of the packaging material, and if the stresses transmitted through the material are greater that the stresses that would be required to damage the delicate part, then that packaging material is probably not appropriate.

Answer to Question 2

The beads are confined in the molding step and therefore expand against each other. This close contact forces the walls of neighboring beads to meet and, if the temperature is high enough, fusion occurs. During pre-expansion, the beads are in an air flow and therefore do not have intimate contact with each other. To further prevent beads from fusing during pre-expansion, the temperature is often a few degrees lower than during molding. Also, liquids can be added during pre-expansion that tend to keep the beads separated.