Santoprene Injection Molding and Nitrofreeze® Cryogenic Deflashing


Santoprene injection molding is used to produce automotive and electrical components, parts for household appliances, and building and construction products. Medical grades of this thermoplastic elastomer (TPE) are molded into parts including medical wearables, devices and equipment. There are many different types of TPEs, but Santoprene belongs to a subcategory called thermoplastic vulcanizates (TPVs) that are based mostly on polypropylene thermoplastic and EPDM rubber.

Nitrofreeze® cryogenic deflashing removes mold flash from Santoprene parts with a computer-controlled, automated batch process that is safe, quick, and efficient. Compared to hand trimming, cryogenic deflashing can save you time and money. Contact Nitrofreeze® to discuss your Santoprene deflashing project or keep reading to learn more about this injection moldable material and why it’s a good candidate for cryogenic flash removal.

What is Santoprene?

As a thermoplastic elastomer, Santoprene combines the processability of a thermoplastic with many of the performance characteristics of a thermoset rubber. Unlike EPDM, however, Santoprene can be recycled. It combines good mechanical properties with environmental resistance and is often used in sealing applications where excellent flex fatigue resistance is required. Flex fatigue, the cracking of a component due to stresses and strains, can cause part or product failure.

Why is Santoprene injection molded?

Santoprene contains very small, fully vulcanized rubber particles that are dispersed in a plastic matrix. This TPV is supplied in pellet form for injection molding, but Santoprene TPE can also be processed with blow molding, extrusion, or thermoforming. Injection molded parts can be produced in high volumes, however, and with high precision and various geometries. Santoprene also supports overmolding and insert molding; processes that mold a polymer over a substrate.

Why use cryogenic deflashing with molded Santoprene parts?

During the injection molding process, excess material can form on the surface of parts. This excess material, known as flash, is usually forced out of the mold cavity at the parting line. Injection molders can remove flash by hand, but manual trimming is labor-intensive, time-consuming, and the results are inconsistent. Plus, a worker can deflash only a single part at a time and may remove too much material. Cryogenic deflashing is a machine-based process that quickly and consistently removes only the flash from batches of parts.

How does Nitrofreeze® cryogenic deflashing work?

Batches of parts are put in a drum inside a cryogenic deflashing machine and subjected to very cold temperatures. By cooling the parts below Santoprene’s glass transition temperature (Tg), the material becomes hard and brittle. This embrittlement allows cryogenic-grade polycarbonate media to remove flash, but without changing the parts’ physical or mechanical properties, part tolerances, or surface finish. This non-abrasive media comes in different sizes and maintains its aggression with holes as small as 0.015” (0.381 mm).

Why use cryogenic tumble deflashing or dry ice blasting?

If residual media may attach to part surfaces or become lodged in part geometries, Nitrofreeze® can process your parts with dry ice deflashing instead. This effectively media-less process blasts batches of parts with particles of dry ice that turn into a gas or vapor (sublimation) after impingement. This eliminate parts cleaning after deflashing, but what if your parts have very small features? Nitrofreeze® can use dry ice blasting to target specific areas, including holes and cavities smaller than 0.015” (0.381 mm).

What’s the best way to deflash Santoprene?

What’s the best way to deflash Santoprene parts? Contact the experts at Nitrofreeze® to discuss your application. No job is too large or too small, and our standard turnaround time is two days after receipt! If your Santoprene part is a viable candidate, we can perform sampling to demonstrate the process we recommend. We can also save your recipe for future batches of the same part. The consultation is free of charge, so send us your part drawings, photos, or samples to get started.

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