Why do you have to clean the barrel and feeding system in medical silicone injection molding when changing the material?


 

Question: Why do you have to clean the barrel and feeding system in medical silicone injection molding when changing the material?

Answer: Cleaning the barrel and feeding system is essential in medical silicone injection molding because it significantly reduces the risk of contamination during the molding process. In thermoplastics injection molding, the barrel is simply purged a few times when changing from one material to another. However, this approach doesn’t completely remove all the material in the barrel and feeding system in silicone injection molding; varying amounts of mixed silicone and purging agent (typically part B of the silicone) will remain in the barrel and feeding system due to their tackiness and low viscosity. As a result, the residual can ultimately get mixed in with the desired material during the subsequent molding process. In addition to cleaning the barrel and feeding system, they should be purged through at least once to remove the cleaning agents.

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