Injection Molding Process Explanation

Home > Resources > Video Center > Manufacturing Description > Injection Molding Process Explanation

Ever picked up a phone case, a keyboard key, or a water bottle and thought: How did plastic turn into this exact shape? The answer is injection molding— the "mass-production wizard" that makes 90% of the plastic parts you use daily. Let’s unlock its 5-step magic.

Step 1: Melt the Plastic

First, we start with plastic pellets—tiny, colorful beads. They’re fed into a heated barrel, where a screw spins to mix and melt them at 300°C. Think of it like kneading hot dough: the plastic turns into a smooth, runny "melt" that’s ready to shape. No lumps allowed—this ensures the final part is flawless.

Step 2: Inject into the Mold

Next, the molten plastic is shot into a custom steel mold at super high pressure—up to 2,000 PSI. The mold is like a detailed cookie cutter, but for plastic: it has every groove, curve, and hole of the final part (even tiny logos!). The plastic fills every nook in seconds—speed is key here for mass production.

Step 3: Cool & SetOnce the mold is full, we wait.

Coolant flows through the mold to quickly chill the plastic—usually 10-30 seconds. This is when the magic "sets": the runny melt hardens into the exact shape of the mold’s inside. It’s like baking a cake, but instead of heating, we cool it to lock in the form.

Step 4: Demold & Check + Wrap-Up

Finally, the mold opens, and a small pin pushes the finished part out—clean, sharp, and ready to go. Inspectors check for tiny flaws (no one wants a lopsided bottle cap!), then it’s off to be packaged or assembled. The best part? One mold can make 1 million+ parts. Injection molding isn’t just manufacturing—it’s turning simple plastic into the stuff we can’t live without.