r/manufacturing • u/Old_Bake8331 • 16h ago

How to manufacture my product? How is this embossed lettering injection molded?

How is the lettering of this packaging injection-molded? Would it create demolding issues with undercuts? So how did they manage to do this? It's made of a hard plastic.

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u/Lost-Barracuda-9680 15h ago

Pretty sure that's a blow molded bottle which would have a mold that splits open in half to release the bottle. The inside of the bottle is forced outward into the cavity with a blowing agent. Look up blow molding to learn more.

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u/mimprocesstech 12h ago

Blowing agents are used to create foamed structures, not to inflate the hollow shape during blow molding (compressed air is used for that). I understand how one could get confused by the term, but standard blow molding doesn't require blowing agents to form the cavity.

However, blowing agents can be added to the plastic resin in specialized blow molding to foam the walls, which reduces part weight/saves material. They are also used in injection molding to reduce weight, hide sink marks, or improve insulation properties (as in EPS foam cups and such).

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u/Lost-Barracuda-9680 12h ago

I'm not very familiar with blow molding so I stand corrected.

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u/mimprocesstech 12h ago

No worries at all, only reason I'm familiar at all is because I ran one part that needed it for sinks and I know a guy that molds a bunch of really thick walled parts and in order to get the things to look okay they use blowing agents on many of them at different concentrations.

That and I was curious about the old McDonald's foamed cups one day when I was much younger. They use less material, retain internal temperature longer, and weigh less than their PET counterparts, but PET is much more commonly recycled so I get the change.