Have you ever noticed the small circular dent on the side of a plastic milk jug? Most people assume it’s a manufacturing flaw or simply part of the design, but it actually serves several important purposes that make these everyday containers safer, stronger, and more efficient.
The dent is engineered to handle changes in pressure caused by temperature fluctuations. As milk warms or cools, the air and liquid inside the jug expand and contract. Instead of allowing the container to bulge, crack, or burst, the dent flexes inward or outward, relieving the pressure and protecting the jug.
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