Injection molding flash, or flashing, is excess material that is forced out of a mold cavity at the parting line or ejector pin locations. This surface defect mars the finish of molded parts and can interfere with their performance. Traditionally, injection molders remove flash by hand. However, manual trimming is slow, time-consuming, and can result in parts with different levels of surface quality.
When a plastic injection molder asked Nitrofreeze® if we could deflash molded plastic clips, we welcomed the challenge. The flash tolerance on the parting line (part exterior) was 0.002” (0.0508 mm) and the ejector pin flash was 0.004” (0.1016 mm). The part material was nylon 6/6 with a 33% glass filler. In small injection molded parts, glass-filled nylon is sometimes used to add strength.
Cryogenic deflashing from Nitrofreeze® provides a fast, efficient, and reliable way to remove flash from batches of injection molded plastic parts. This non-abrasive process removes excess material while maintaining part geometry, surface finish, and critical tolerances. As this Nitrofreeze® proof of concept demonstrates, applications include cryogenic deflashing for molded plastic clips.
Nitrofreeze® Cryogenic Deflashing subjects parts to very cold temperature and then blasts them with a cryogenic-grade polycarbonate media. When a material such as glass-filled nylon is cooled below its glass transition temperature (Tg), it becomes hard and brittle like glass. This embrittlement allows our media to remove the protruding flash, but without changing the physical or mechanical properties of your parts.
Nitrofreeze® uses cryogenic-grade polycarbonate media that comes in different diameters to finish part features without affecting critical surface tolerances. Except for the absence of flash, your molded parts look the same as they did before. For the molded plastic clips, Nitrofreeze® selected the proper media size and exceeded the client’s requirements for parting line and ejector pin flash removal.
This YouTube video shows Nitrofreeze® cryogenic deflashing in action. In addition to glass-filled nylon, our process is suitable for plastic and rubber materials such as polycarbonate, Delrin®, EPDM, polypropylene, silicone, neoprene, and polyurethane. Cryogenic deflashing is often used with injection molded parts but it can also be used to remove flash after compression molding or transfer molding.
Contact the deflashing experts at Nitrofreeze® to discuss your project requirements. If your part is a viable candidate for our process, we can perform proof of concept samples. The consultation is free of charge, so contact us at the phone number or email below.
(508) 459-7447 x 105