Worried about your plastic slippers being uncomfortable or falling apart too quickly? It is important to know the technical details.
Plastic slipper injection molding involves precise temperature, pressure, and timing control to ensure quality, durability, and comfort.
You might think it’s a simple process, but there’s more than meets the eye. Let’s dive in!
What is the process of plastic injection molding?
Are you curious about how those comfortable EVA plastic slippers are made? It is injection molding and involves several key stages.
Plastic injection molding is a manufacturing process where molten plastic is injected into a mold cavity, cooled, and then ejected as a finished product.
To better explain the process, I’ll break it down into smaller steps.
Key Stages of Injection Molding
Let’s examine each of these stages in detail:
| Stage | Description | Technical Points |
|---|---|---|
| 1. Clamping | The mold is closed and secured by the clamping unit. | Clamping force must be sufficient to withstand the injection pressure. Insufficient force can cause flashing or mold damage. The clamping unit should operate smoothly and consistently. |
| 2. Injection | Molten plastic is injected into the mold cavity under high pressure. | Injection speed and pressure are critical. Too fast can cause material degradation, while too slow can lead to incomplete filling. Melt temperature needs to be precise to ensure proper flow and prevent burning. |
| 3. Dwelling | Pressure is maintained to ensure complete filling of the mold as the plastic cools and shrinks. | Holding pressure and time need to be optimized to prevent sink marks or voids. Too much pressure can cause stress in the part. It is necessary to monitor the pressure during this phase. |
| 4. Cooling | The plastic cools and solidifies inside the mold. | Cooling time is crucial. Insufficient cooling can result in deformation upon ejection. Cooling channels in the mold must be designed for uniform heat removal. The temperature of the coolant also matters. |
| 5. Ejection | The mold opens, and the finished part is ejected. | Ejection force must be sufficient to remove the part without damage. Ejector pin placement is important to prevent distortion or breakage. The mold should be designed for easy part removal. |
From my experience at Ningbo Cotton Slipper Co., Ltd., I know that each stage requires meticulous attention to detail. For example, when we were creating a new design for a client in South America, we had issues with sink marks on the surface of the slippers. We had to adjust the holding pressure and cooling time to resolve the issue. This is what we do every day.
Conclusion
Injection molding is all about precision, because that’s how we create high-quality slippers.
