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They’re only important if the next stage is a plan to go to more rigid, higher production capacity methods. Injection molding demands thorough care with draft angles to enable smooth ejection. Building them saves time for knock-on design changes later. Your model would closely match the final part. For a prototype or one-off design, they’re basically of no value. Silicone molds are so flexible they allow you to focus on part function without worrying about extraction. However, where a part’s geometry has deep or sharp features, adding draft angles might extend the mold's service life by reducing stress.

[Pete Read]

hi, I’m designing the master model for a silicone mold (for vacuum casting) and wondering about the necessity of incorporating draft angles. Is it always required to include draft angles in the design, or are there specific cases where the material properties, mold complexity, or part geometry allow for skipping them? These holes in a cutaway detail are a good example, should I draft or not draft? thank you

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[Rafael Angulo]

No, draft angles aren’t strictly necessary when vacuum casting in silicone molds, but they might help in these long draws if you drill to parallel after casting. The flexibility of silicone means it can handle undercuts and intricate geometries without the need for any consideration of draft angles. This makes it easy to create complex shapes that would otherwise need much more complexity/processing in rigid molds.

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[Pete Read]

thanks. In what situations would you recommend adding draft angles?

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[Rafael Angulo]

They’re only important if the next stage is a plan to go to more rigid, higher production capacity methods. Injection molding demands thorough care with draft angles to enable smooth ejection. Building them saves time for knock-on design changes later. Your model would closely match the final part. For a prototype or one-off design, they’re basically of no value. Silicone molds are so flexible they allow you to focus on part function without worrying about extraction. However, where a part’s geometry has deep or sharp features, adding draft angles might extend the mold’s service life by reducing stress.

• This reply was modified 7 months, 2 weeks ago by
  R
  Rafael Angulo.

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