plastics

[chemclass101]

I wanted to know what goes into the process of plastic manufacturing… for example are molds used? Are there coatings that are used on the molds, if so why and how do they work? I have recently come to understand that the foundry industry uses coatings on sand cores to improve the metals surface finish… how closely are the foundry and plastic industries related? Thanks in advance!

[YT2095]

way too Broad a question!

 

there are Dozens of different methods used, Injection molding, vacuum molding, extrusion, tumble casting, spray deposition etc....

 

some molds are coated some are not, some have inserts some don`t...

 

although I know of no process that uses sand casting for plastics, at least never in my experience.

[chemclass101]

What type of process would be most closely related to the foundry process? Are the coatings used as a way to release the plastic from the mold or what else are they used for? I know very little about the manufacturing of plastics, so any detailed information that walks me through the process start to finish would be helpful... is there a website that would be helpful to use?

[YT2095]

probably the Closest would be Latex or powder tumble molding, the die is coated (sometimes) with an agent that allows it release easily, then the liquid or powder is poured in and then the mold is moved around to coat all surfaces, in the case of powder this is done in a heated environ, a machine does all the movements.

then after a set time it`s taken out allowed to cool a little and the item (hollow) taken out.

 

think Plastic latex doll heads and such.

 

Injection molding is close to casting too, only Pressure does the work for the liquid thermosetting plastic rather than gravity.