Cyrogenic deflashing removes mold flash from plastic and rubber parts for improved appearance and performance. There are three different versions of this surface finishing process. The first, known simply as cyrogenic deflashing, freezes parts and blasts them with plastic media. The second, cyrogenic tumble deflashing, combines the advantages of cryogenic deflashing with dry ice deflashing, an effectively media-less process. Dry ice deflashing has other advantages as well, but this third process is for individual parts instead of batches.
Cryogenic deflashing begins when batches of molded parts are put in a perforated drum inside a machine and subjected to very low temperatures. Each polymer has a different glass transition temperature (Tg), but the desired result is the same. A polymer that’s cooled below its Tg becomes hard and brittle like glass, and this embrittlement allows cryogenic-grade polycarbonate media to remove flash from your molded parts. Importantly, this process does not change the parts’ physical or mechanical properties.
Cryogenic deflashing is suitable for a wide range of plastic and rubber materials. The cryogenic-grade polycarbonate media that Nitrofreeze® uses comes in different lengths and diameters to meet application requirements and reach part features. Cryogenic deflashing doesn’t affect part tolerances, but some media may attach to part surfaces or become lodged in part geometries. In part, that’s why some molders may choose cryogenic tumble deflashing instead.
Cryogenic Tumble Deflashing
Cryogenic tumble deflashing blasts parts with particles of dry ice instead of plastic or other abrasive media. Molded parts are placed inside a chamber and subjected to a stream of dry ice particles. Nitrofreeze® can use either solid or liquid CO2 as the source of the dry ice and adjust the quantity or size of the particles that are delivered while the parts are tumbled. Coverage density, spray patterns, and air pressure are just some of the other process variables that we can tailor to your application.
Importantly, the dry ice particles in the cyrogenic tumble deflashing process sublimate after impingement. In other words, they turn to a gas or vapor. Unlike traditional cryogenic deflashing then, there’s no residual media to attach to part surfaces or become lodged in part geometries. This eliminates the need for parts cleaning after deflashing, but there’s more than just this to consider. At Nitrofreeze®, the location and intensity of the mold flash determine which cryogenic deflashing process we recommend.
Dry Ice Deflashing
The third and final cryogenic deflashing technique, dry ice deflashing, is used with individual parts instead of batches of parts. Known also as dry ice blasting, it supports the removal of mold flash from challenging geometries such as internal holes, cross-holes, blind holes, small slots and crevices. During dry ice deflashing, high-pressure air blasts dry ice media at very specific areas.
Dry ice deflashing is recommended for holes and cavities with less than a 0.015” (0.381mm) opening. Although dry ice sublimates too quickly for reliable measurements at smaller sizes, Nitrofreeze® has cleaned cavities as small as 0.003” (0.0762mm) with dry ice blasting. Cryogenic deflashing can also clean smaller inner diameter features, but the polycarbonate media that’s used tends to lose its aggression with holes and cavities that are smaller than 0.015” (0.381mm).
Choose the Best Cryogenic Deflashing Method
What’s the best way to remove mold flash from your plastic or rubber parts? Contact the experts at Nitrofreeze® to review your requirements. If your molded part is a viable candidate for any of our cyrogenic deflashing techniques, we can perform sampling to demonstrate our process. The consultation is free of charge.
To learn more, contact us at the phone number and email listed below.
(508) 459-7447 x109 | firstname.lastname@example.org