Cryogenic deflashing for plastic parts is an automated batch process that removes mold flash, excess material that affects surface quality and can cause problems with sealing and assembly. During cryogenic deflashing, molded parts are put in a perforated drum, subjected to cryogenic temperatures, and blasted with plastic media. The cryogen, a gaseous nitrogen, embrittles the flash. The blast media, a cryogenic-grade polycarbonate, is non-abrasive and removes the flash without impacting critical part tolerances or surface finish.
Why Do Plastic Parts Have Mold Flash?
During the plastic injection molding process, flashing can occur because of parting line mismatches, improper venting, inadequate clamping pressure, poor sprue bushing support, or excessively low viscosity. Worn tooling, a frequent cause of parting line mismatches, can be expensive to replace or inconvenient to refurbish. Flash-less molds are available, but they can double or even triple your tooling costs. No matter the cause of plastic flash, injection molders need an effective way to remove it.
How Does the Cryogen Work?
Cryogenic plastic deflashing uses gasesous nitrogen as the cryogen to subject batches of molded parts to very low temperatures. Each plastic has a different glass transition temperature (Tg), the temperature range at which a polymer changes from a hard, rigid state to a more pliable, compliant state. A polymer that’s cooled below its Tg becomes hard and brittle like glass, and this embrittlement allows cryogenic-grade polycarbonate media to cleanly remove flash from your molded plastic parts.
How Does the Blast Media Work?
The cryogenic-grade polycarbonate (PC) media that Nitrofreeze® uses is strong, impact-resistant, and has a very low brittleness temperature. It’s formed into beads and cylinders and comes in a range of lengths and diameters to access hard-to-reach part features. Because this blast media is non-abrasive, it won’t leave behind dust or residues that require extensive cleanups. Cryogenic-grade PC media can be reused and recycled, too.
Why is Cryogenic Parts Deflashing Better Than Hand Trimming?
Compared to hand trimming, cryogenic deflashing provides faster cycle times, reduced labor costs, and greater-part-to-part consistency. Plastic molders especially like how cryogenic treatment can remove flash from cross-holes, blind-holes, and other challenging geometries. Because our process is computer-controlled, we can also save the optimal deflashing “recipe” for future batches of the same molded parts.
Is Cryogenic Deflashing Always the Right Choice?
Cryogenic-grade polycarbonate tends to lose its aggression with very small hole and cavities. That’s why dry ice blasting is recommended if the openings are less than a 0.015” (0.381mm). 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.
What’s an Example of Cryogenic Plastic Deflashing?
An injection molder asked Nitrofreeze® to remove flash from molded aerospace parts made of PEEK, an engineering thermoplastic. After evaluating sample parts, we developed proprietary processing parameters and performed initial sampling. Our team then extrapolated a process for production runs over a hundred parts per cycle. The transition from hand trimming to Nitrofreeze® cyrogenic deflashing enabled the injection molder to achieve consistent quality while reducing costs by 83.4%.
Is Your Molded Part a Candidate for Cryogenic Plastic Deflashing?
What’s the best way to remove mold flash from your plastic parts? Contact the experts at Nitrofreeze® to discuss your application. If your part is a viable candidate for cryogenic deflashing, we can perform sampling to demonstrate our flash removal process. The consultation is free of charge, so send us your drawings, photos, or part samples. No job is too large or too small, and our standard turnaround time is two days.
To get started, contact Nitrofreeze® at the phone number and email listed below.
(508) 459-7447 x 109 | firstname.lastname@example.org