how milk jugs are made - pet manufacturing process
Milk cans are usually made of high density polyethylene or high density polyethylene.
In the manufacturing process of milk cans, high density polyethylene particles are usually mixed with recycled high density polyethylene flakes.
Because high density polyethylene loses its durability after use, only a limited number of recycled flakes can be used.
After mixing the high density polyethylene particles and flakes, they slide down a tube and place it in a plastic injection molding machine.
There, the material is heated to 599 degrees Fahrenheit.
When the material becomes thick and sticky plastic, it is injected into the mold that makes "pre-formed.
"These tubes look big and thick.
Because of a built in, they harden almost instantly
In the cooling machine.
The pre-formed bodies are sent down along a line where they enter a machine called a re-thermal stretch blow molding machine.
In a few seconds, each pre-made stick is heated enough to bend the plastic again.
Place a stick inside the pre-made stick, stretch it out, while blowing hot air inside the pre-made stick.
When the premade bar is heated and stretched, it is stuck in the mold until it looks like a plastic milk can.
Cool the kettle almost instantly through the cold water of the mold, hardening the plastic.
All of this happens within a few seconds.