Nitrofreeze® cryogenic deflashing removes mold flash from parts produced using silicone rubber overmolding, a multi-step process that molds silicone rubber over parts made from another material. Examples include medical devices where silicone is molded over metal to provide protection against water, heat, impact, and electrical shock. Silicone can also be molded over plastic during two-shot molding.
Silicone Overmolding and Part Deflashing
Silicone rubber overmolding can use either liquid silicone rubber (LSR) or silicone high-consistency rubber (HCR). LSR overmolding applications include wearables, seals, gaskets, fluidic components, catheters, and medical implants. HCR overmolding is also used in healthcare applications, and LSR and HCR silicone overmolding are both used with auto parts, electronics, and consumer goods.
Silicone overmolded parts can be produced with injection molding, compression molding, or transfer molding. During each of these molding processes, excess material called flash can escape between the mold’s parting line, the area where the mold core and mold cavity meet. Flash detracts from the appearance of molded parts, but it can also interfere with sealing, seating, and product assembly.
Silicone overmolders can remove flash by hand, but trimming is time-consuming and labor-intensive. It’s also inconsistent and may result in the removal of too much or too little material. Using handheld knives and blades can also result in worker injuries. At a time when good employees are hard to find, silicone molders can save time and money by outsourcing parts deflashing to Nitrofreeze®.
Cryogenic Deflashing for Silicone Overmolded Parts
Nitrofreeze® cryogenic deflashing is a clean, safe, and cost-effective way to remove flash from batches of silicone overmolded parts. The process begins when your parts are placed in a perforated drum inside our computer-controlled equipment. Your parts are then subjected to low temperatures and blasted with a fine polycarbonate media that won’t damage part surfaces or leave behind residues.
This non-abrasive, cryogenic-grade media is sized for the job, and Nitrofreeze® can save your cryogenic deflashing recipe for future batches of the same part. When silicone’s glass transition temperature is reached, mold flash becomes hard and brittle. It’s this embrittlement that allows the polycarbonate media to remove flash upon impact – and without affecting critical part tolerances or surface finish.
Flash along straight edges is easy to remove cleanly, but Nitrofreeze® cryogenic deflashing for silicone rubber overmolding can also remove flashing from more complex geometries. For example, when a customer asked us to cryogenically deflash silicone overmolded springs, Nitrofreeze® removed flashing from both the outer and inner diameters. Because we could deflash these parts in large batches, Nitrofreeze® offered an attractive per-piece price.
Ask Nitrofreeze® to Deflash Your Overmolded Silicone Parts
Silicone overmolding lets part designers leverage the properties of multiple materials, such as a harder plastic or metal and a softer silicone. However, flash can detract from the appearance of silicone overmolded products and interfere with their performance. Fortunately, there’s a better way to remove mold flash than hand trimming.
Contact the experts at Nitrofreeze® to discuss your project 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 patented process. The consultation is free of charge, so send us your part drawings, photos, or actual part samples.
To get started, contact Nitrofreeze® at the phone number and email listed below.
(508) 459-7447 x 105 | info@nitrofreeze.com