After molding the part, we often aren’t finished. Cryogenic de-flashing systems are computer controlled to precisely control flash removal without damage to the part. In this process, the parts are cooled to the embrittling point of the material. Once brittle, the parts are subjected to a fine mesh media which helps to break off the excess flash.
Cryogenic deflashing is used to remove flash (flash=byproduct of the molding process / unwanted-excess material) from molded rubber parts. The main chamber houses a deflashing basket that ranges in size from 1 to 5 cubic feet. The basket rotates at varying speeds in an effort to expose rubber parts to the plastic shot-blast media. The plastic media, which can be recycled and re-used several times, is expelled from the throw wheel at speeds up to 10,000 RPM. Once the deflashing process begins, the chamber fills with liquid nitrogen causing parts to go from ambient to freezing temperatures ranging from 0F to -175°F.
Dialing in the proper parameters is crucial to successfully removing flash without damaging parts. Based on part geometry, size, polymer, and basket volume, we can determine the appropriate temperature, RPM (speed of the throw wheel), cycle time, and basket speed. For example, a silicone part will require a colder deflashing cycle because the brittle point is much lower. What’s more, a part with overflow flash will need a longer cycle and likely a higher RPM speed as opposed to parts with thin or feather flash.
Cryogenic deburring is a robust, efficient approach with parts that have critical and complex dimensions that contain flash or when other methods are not available or economical, such as tear or hand-trimming.