Deflashing is a finishing process for plastic moldings. A flash or rind sometimes remains after plastics have been molded, and deflashing services may be needed. Typical deflashing methods are blast finishing, tumbling, abrasive belts (wet or dry), use of scrapers, knives and files. Cryogenic deflashing is often used for thermoplastic parts. This method involves chilling the parts with liquid nitrogen and tumbling the thermoplastics.

Deflashing Company Links

  • Arrow Cryogenics Inc.: Providing cryogenic deflashing and deburring and finishing services for metal, plastic, and rubber.

Flash & Deflashing

Flash (or flashing) is excess material left on a molded, forged, or cast product, such as an injection molded plastic product. The presence of flash is usually caused by leakage of the material between two or more surfaces of a mold, generally along the parting line, or, in overmolding processes, between the base material and the mold. For proper use of the product, the flashing must be removed.

The process of removing flash is called deflashing. Deflashing is commonly accomplished via cutting, grinding, breaking, or tumbling. Depending on the material being deflashed, robotic autogrinders may be used.

In plastic injection molding, “witness marks” (faint lines that occur along the mold’s parting line) are common. The presence of witness marks is generally acceptable for the finished product.

Cryogenic Deflashing

Cryogenic deflashing is an efficient deflashing and finishing method. Extremely low temperatures are used in this process, making flash stiff or brittle, and easy to break away. With this method, metals, rubbers, plastics, and silicones can be deflashed.

Liquid nitrogen or another cryogen is generally used to cool the workpieces, which are then tumbled or blasted to remove flashing. Cryogenic deflashing offers consistent batch to batch results, and can be performed relatively quickly at low cost. It is also non-abrasive, which helps maintain the finish of the products being deflashed.

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