Dip molding and coating is a plastics process that, while used commonly on many types of products that include everything from medical devices to hand tools to gasoline pump handles, remains largely unknown to many plastics engineers and product designers. Yet, dip molding and coating using a variety of liquid polymers offers many advantages and, in certain applications, can even be an excellent alternative to the injection molding and extrusion processes.
There are a number of advantages to dip molding and coating that makes these processes both cost-effective and time-efficient. The molds, called "mandrels," are typically needed for the dip molding process or for custom applications, and are made from either aluminum or steel. These mandrels can be made in a matter of hours, making them extremely cost-effective compared to the tooling required for other plastic processes. That means that samples can be provided in days, and production started in just a few weeks.
Depending on the number of mandrels needed for the project (based on the volumes required), capital costs are typically under $2500. In the dip molding process, the mandrels are heated and then "dipped" into the liquid polymer, natural and synthetic rubber, and even latex for certain applications. The material attaches to the mandrel, with the thickness of the product determined by the "dwell time" or the length of time the mandrel remains in the liquid polymer. The mandrels are then placed in an oven using heat to cross-link or "cure" the liquid polymer into a solid state. This "cure time" can vary by part.