Why Aluminum Zarges Cases Are Stronger Than Plastic Pelican Cases
Why Zarges Cases Dent And Don't Break
As a new sales representative for Zarges transit cases in New England and downstate New York, I wanted to know why Zarges cases were stronger than Pelican cases - the real engineering answer, not the marketing answer. After all, I'd be selling to engineers and they too would want to know WHY they should use Zarges cases instead of specifying plastic Pelican cases.
I found out that the fundamental reason that Zarges cases are stronger than Pelican cases is because they dent, but don't break like Pelican cases will. That's due to their Modulus of Elasticity and their Ultimate Tensile Strength material properties. Look at the large differences between the Aluminum used in Zarges cases, compared to the plastics, polypropylene and polyethylene HDPE, used in Pelican cases*.
E is the ratio of tensile stress to tensile strain.
Ultimate tensile strength is the force the material withstands before it breaks into two or more pieces.
And from your personal experience you already know that at cold temperatures plastic cracking is a problem. Here's the engineering proof of that. At -10ºC a plastic HDPE case only has about 1/3 of the strength as it had at room temperature. (The end of each temperature line in the graph below is where the plastic breaks.)
HDPE Plastic Gets Weak at Cold Temperatures
While Aluminum's Modulus of Elasticity stays linear and varies relatively little even over the huge temperature range of -200ºC to +200ºC.
In summary, the engineering answer is:
- Zarges cases will just dent, while Pelican cases will crack under the same tough conditions.
- Aluminum deforms much more than plastic before finally breaking apart.
- Aluminum is about three to seven times stronger than plastic to begin with at room temperature.
- Aluminum stays strong in the cold while plastic really weakens.
Zarges K470 Aluminum Case
Other engineering reasons to specify Zarges cases:
- Weight - lighter than plastic Pelican cases.
- Size - smaller for the same inside volume.
- Temperature - wider range.
- EMI protection - inherent to Aluminum
- Fire - configurable so a Li-Ion battery that catches fire inside the case will only warm the outside of the case!
*BTW, I didn't do any testing myself on these materials, I just pulled the generic material properties from the web and charted them.