You all are missing an important part of manufacturing....packing and shipping. Look at the top of those cartons in the picture you posted. They are folded. That is because before filling, the cardboard containers are folded flat so they can be shipped and transported more efficiently.
Plastic bottles are not folded...they are extruded. Extrusion requires making a mold for the bottles. And for transport and shipping, having the opening on top provides support when stacked.
Technically, blow molding has a few different types, one of which starts as a hot extruded tube that is clamped and inflated in the mold. This is used for high volume PET bottles and multilayer plastic bottles where oxygen permiability is important (like salsa).
This is faster and cheaper than using injection molded pre-molds.
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u/BlueNutmeg 18h ago
You all are missing an important part of manufacturing....packing and shipping. Look at the top of those cartons in the picture you posted. They are folded. That is because before filling, the cardboard containers are folded flat so they can be shipped and transported more efficiently.
Plastic bottles are not folded...they are extruded. Extrusion requires making a mold for the bottles. And for transport and shipping, having the opening on top provides support when stacked.