Molded Silicone Parts

Cryogenic Deflashing for Molded Silicone Parts


Cryogenic deflashing for molded silicone parts removes flash for improved appearance and performance. Mold flash is often a cosmetic defect, but silicone molders want to avoid the appearance of surface imperfections that suggest poor quality. With parts such as silicone gaskets or O-rings, flash that affects a part’s surface finish can interfere with proper sealing. The causes of flash are numerous, but molders and manufacturers who use cryogenic deflashing can achieve consistent, high-quality results.

Silicone mold flash can be trimmed by hand, but manual deflashing is labor-intensive and time-consuming. Hand trimming is also inconsistent since different workers may achieve different results. There can even be part-to-part differences by the same worker during the same shift. Outsourced deflashing might seem expensive, but cryogenic deflashing is an automated, computer-controlled batch process that can save silicone molders and manufacturers time and money.

How Cryogenic Deflashing Works 

Cryogenic deflashing begins when batches of molded parts are put in a perforated drum and subjected to very low temperatures. Like other polymers, silicone has a glass transition temperature (Tg) below which it becomes hard and brittle like glass. In turn, this embrittlement allows the cryogenic-grade polycarbonate media that impacts the molded silicone to remove the flash. The cryogenic-grade media that Nitrofreeze® uses can reach application-specific part features but won’t affect part tolerances.

This YouTube video shows how the cryogenic deflashing process works. Nitrofreeze® has used cryogenic deflashing on many different types of molded silicone parts, including blocks and bumper stops, distal handles, O-rings, gaskets, housings, overmolded springs, and electrical grommets. Proof-of-concept case studies with photographs are available on the Nitrofreeze® website, but the following sections provide an overview of some of the cryogenic deflashing work we’ve performed.

Silicone Blocks and Bumper Stops

Nitrofreeze® cryogenic deflashing removed mold flash from silicone bumpers stops that were gray in color and rectangular in shape. Block-shaped silicone implants are used in surgical applications.  In building and construction, silicone blocks provides an alternative to mortar. Nitrofreeze® used cryogenic deflashing remove both outer diameter (OD) flash and inner diameter (ID) flash.

Silicone Distal Handles

Nitrofreeze® cryogenic deflashing removed mold flash from silicone distal handles that are used with handheld instruments. The silicone molder had tried buffing and trimming, but these manual methods were becoming too labor-intensive. Nitrofreeze® cryogenic deflashing saved over 6 hours of deflashing labor for every 1,000 pieces. Typical volumes were 3,000 to 4,000 parts per release.

Silicone O-Rings and Gaskets

Nitrofreeze® cryogenic deflashing removed mold flash from a 1.50” OD silicone O-ring for the oil and gas industry. Quality assurance revealed that our process achieved the required tolerance of 0.005” while removing both OD and ID flash. Nitrofreeze® cryogenic deburring has also been used with both round silicone gaskets and square silicone gaskets.

Silicone Housings, Overmolded Springs, and Electrical Grommets

Nitrofreeze® cryogenic deburring eliminated mold flash from silicone housings made of 60 durometer (Shore A) liquid silicone rubber (LSR). The part measured 1 cubic inch and had parting line flash that was 0.005” thick and extended 0.200”.  Production lot sizes averaged 2,000 pieces per week. With both the silicone overmolded springs and the 60-durometer silicone electrical grommets, cryogenic deflashing met all of the requirements.

Cryogenic Deflashing for Your Molded Silicone Parts

What’s the best way to remove mold flash from your silicone parts? Contact the experts at Nitrofreeze® to discuss your requirements. No job is too large or too small, and our standard turnaround time is two days after receipt. If your part is a viable candidate for cryogenic deflashing, we can perform sampling to demonstrate our process. The consultation is free of charge, so send us your part drawings, photos, or actual samples of molded silicone parts.

To get started, contact Nitrofreeze® at the phone number and email listed below.

(508) 459-7447 x 109 |