Plastic molding can produce parts with flash, excess material that forms on part surfaces. During injection molding, molten plastic may escape through the mold’s parting line. Improper venting, low clamping pressure, low material viscosity, and uneven flow can also cause flash formation. In addition, injection molding flash sometimes occurs after the gate runners are removed.

Flash also occurs during compression molding, typically because the material charge was loaded in excess. Other types of plastic molding, such as transfer molding and blow molding, can produce parts with flashing, too. Some companies remove this unwanted material one part at a time by hand, but that’s inefficient with batches of plastic parts, especially using high-volume processes like injection molding.

Mold Flash and Part Tolerances

For plastic molders, it’s important to remove flash to meet customer specifications. That’s especially true for medical, aerospace, and other applications with tight tolerances. If a molded part is designed for a larger assembly, flash may prevent components from fitting together correctly. Mold flash can also interfere with seating and sealing.

In high-precision injection molding, designers specify tolerances that are significantly tighter than those used in most consumer applications. Yet for any type of plastic molding project, there’s more than just one type of dimensional specification to consider. Straightness/flatness, hole diameter, blind hole depth, and concentricity/ovality each have their own tolerances.

How Cryogenic Deflashing Works

Nitrofreeze® cryogenic deflashing is a quick, consistent, and cost-effective way to remove flash without affecting critical tolerances. The process begins when a batch of parts is put inside a basket that’s loaded into a cryogenic deflashing machine. The parts are then cooled below the plastic’s glass transition temperature and impacted with a non-abrasive, cryogenic-grade polycarbonate media while being tumbled.

This special polycarbonate media removes only the flash, which becomes hard and brittle once the plastic’s glass transition temperature is achieved. In other words, Nitrofreeze® cryogenic deflashing won’t change critical part tolerances. This patented process won’t mar the parts’ surface finish either. These aren’t the only benefits.

More Benefits for Plastic Molding Companies

The cryogenic-grade polycarbonate media that Nitrofreeze® uses comes in varying lengths and widths. That’s important because deflashing a part’s internal dimensions requires media that’s small enough to access these spaces. By using media sized from 0.015” to 0.060”, Nitrofreeze® cryogenic deflashing can reach inside demanding part geometries.

Plastic molding companies that use Nitrofreeze® cryogenic deflashing also benefit because the process is computer-controlled, automated, and repeatable. Compare that to hand trimming. During manual deflashing, workers may remove too much or too little material. Critical tolerances and surface finish are at risk, and deflashing just one part at a time can result in part-to-part variations.

Choose Nitrofreeze® Cryogenic Deflashing for Molded Plastic Parts

Are your molded plastic parts suitable for cryogenic deflashing? Contact the experts at Nitrofreeze® to review your requirements. If your part is a viable candidate, we can perform sampling to demonstrate the process. The consultation is free of charge. To learn more, contact us at the phone number and email listed below.

(508) 459-7447 x109 | info@nitrofreeze.com