Dip molding with plastisol is a thermal process that creates a molded part from a liquid form of PVC (Polyvinyl chloride). If that sounds confusing, you’re not the only one. Many people don’t understand exactly how dip molded parts are created. That’s why we’ve laid out each step that’s involved to help you better understand the dip molding process.
Step 1: Preheat the mandrel
The mandrel is the form that is used to create the part you’re trying to produce. In other words, it’s the mold that creates the dip molded part, and is a “negative” of the inside of your finished part. These mandrels are preheated to a specific temperature depending on the materials used and the required thickness of the part. Metal mandrels are typically used for dip molding, as these can withstand the temperatures required of the process.
Step 2: Dip the mandrel in the liquid polymer
Once the mandrel is preheated to the appropriate temperature, it is then dipped into plastisol (a thermoplastic liquid form of PVC). As the heated mandrel is immersed in the plastisol, the PVC begins to thicken and gel on its surface. The thickness of the part can be controlled by the temperature of the mandrel entering the plastisol, and the dwell time within the plastisol. Once the appropriate thickness is achieved, the mandrel is withdrawn from the plastisol.
Step 3: Post-heat and cooling
After removing the mandrel from the plastisol, it is then heated again. This post-heat step allows the plastisol to fully fuse in such a way that when the part cools, the plastisol is no longer a liquid, but a solid piece of PVC.
Step 4: De-Mold and repeat
Once the part cools on the mandrel enough so that it won’t be damaged, the part can be removed. The mandrel is now ready for another cycle, and the entire process can be repeated. Have further questions about the dip molding process? Then feel free to contact the pros over at Piper Plastics for all of your dip molding needs.