Silicone Molding（Vacuum casting） Process Explanation

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Ever seen identical silicone parts—like phone cases, medical seals, or toy components—and wondered: How do they make so many copies without expensive molds? The answer is silicone molding: a "low-cost magic" that turns 1 prototype into 100 perfect replicas. Let’s break down how it works, in 5 simple steps.

Step 1: Prep the Prototype

First, we need a "master"—usually a 3D-printed or CNC-machined part. We sand its surface until it’s smooth (no tiny bumps allowed!) and coat it with a release agent. This is key: it lets the silicone pull away later without sticking, like greasing a cake pan before baking.

Step 2: Make the Silicone Mold

Next, we build a frame around the prototype and pour liquid silicone over it. Then comes a crucial step: vacuum degassing. We put the whole thing in a vacuum chamber to suck out every tiny bubble—because even a small bubble would ruin the mold’s detail. After that, we let it cure in an oven for 2-4 hours, until it’s firm like a rubber eraser.

Step 3: Pour the Resin

Once the silicone mold is ready, we carefully cut it open (like opening a clamshell) and remove the original prototype. Now we have a hollow "negative" of the part. We mix liquid resin (the material for the final silicone parts) and pour it into the mold. Another quick vacuum pass gets rid of any new bubbles, then we cure it again—this time, the resin hardens into the shape we want.

Step 4: Demold & Finish + Wrap-Up

Last step: peel the silicone mold off the cured resin part. Most parts are already smooth, but we might trim tiny excess edges with a knife. The best part? This same silicone mold can be used 20-50 times to make more parts. From custom gadgets to medical tools—silicone molding turns small-batch ideas into real, usable products, fast.