Mold Release in Rotational Molding
Using proper mold release techniques is key to the overall quality of your roto-molded parts. It’s important to choose the correct release agent for the specific type of material that you are processing. Many mold release suppliers have very specific releaseagents that are designed to be used with a particular resin type. It’s also very important to understand the specific application instructions of the release agent you choose as most are different depending on the type of agent and the material it will be used with. Release agent suppliers will also have release agents that are designed with low, medium, and high slip that you can choose from. It’s again very important that you understand what you need and where it will be used on your molds. As an example, we wouldn’t necessarily recommend using a high slip release agent on flat surfaces (or much release at all) but would use it for where it is best designed for: in deep cores, removable pins, and parting lines. If using different release agents, it’s important that the containers used at the machine are clearly labeled so that machine operators understand which release agent is which. We have seen issues with operators getting confused, especially if they are new employees. Some release agents will need a proper bake cycle after being applied while other don’t. This is critical as you can be easily confused trying to understand why your part keeps sticking. We suggest applying the release agent to a warm mold, regardless of the bake cycle requirements. Typically, we like to see the inner mold surface at 130°F or slightly above before applying the agent. If you have a cold mold, you will usually need to do a quick pre-heat in the oven for a few minutes and then bring it back out before applying the agent. This step always seems to help the release agent get a better bond to the inner mold surface and last longer. Lastly, more is not always better when it comes to release agents. Just because a part sticks doesn’t mean that you have a release problem. You should ensure that your part sticking issue is caused by mold release before you decide to increase the amount of release agent used.
For more information, or to discuss your specific needs, please feel free to reach out to your Entec Polymers Sales Representative. Educating and training your Team about release agents, and how to properly apply them, is critical to your operation and can help reduce your cost of quality. Thank you for taking the time to review our release agent information and let us know if you have any questions regarding the type and proper use of release agents.
