insert molding | overmolded electrical connectors

Nitrofreeze® Cryogenic Deflashing for Insert Molding


Nitrofreeze® cryogenic deflashing for plastic insert molding gently removes flash from parts and products like electrical connectors and surgical tools. During insert molding, a plastic or rubber material is molded over a substrate that has been inserted into the mold. In the case of an electrical connector, this substrate is an electrically conductive metal. The plastic or rubber provides electrical insulation, and the molding process combines multiple materials to form a single part without the need for secondary assembly.

Mold Flash and Electrical Connectors

With overmolded electrical connectors, plastic insert molding may leave excess molding material on the pins or contacts. Known as flash, this excess material escapes between the mold’s parting line, where the two halves of the mold meet. Insert molding isn’t limited to injection molding, but injection molds are susceptible to flash because they apply significant clamping pressure over many cycles. Along with metal fatigue, injection mold wear can be caused by excessive or improper mold cleaning.

Unless flash is removed properly, the pins that are used with electrical connectors might not plug in easily or form a reliable connection. It’s important to remove this excess rubber or plastic cleanly, but without damaging the electrically conductive contacts, which are thinly plated. While it’s possible to remove mold flash by hand, manual deflashing is time-consuming and labor-intensive because employees can only process one part at a time. It can also be inconsistent since different employees have varying skill levels.

Cryogenic Deflashing for Insert Molded Parts

Nitrofreeze® cryogenic deflashing plastic parts is a clean, consistent, and cost-effective way to remove flash from batches of insert molded parts. The process begins when parts are placed in a perforated drum inside a computer-controlled machine. The insert molded parts are then subjected to very low temperatures while being blasted with a fine polycarbonate media. Nitrofreeze® sizes this non-abrasive, cryogenic-grade media for the job, and it won’t damage surfaces or leave behind excessive residues.

When the plastic or rubber for an insert molded part approaches its glass transition temperature, the mold flash becomes hard and brittle. This embrittlement allows the polycarbonate media to cleanly remove the 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 can also remove flashing from complex geometrics and part features.

Medical Insert Molding and Flash Removal

As with electrical connectors, medical insert molding requires clean, consistent, and cost-effective flash removal. Nitrofreeze® cryogenic deflashing works well with rubber insert molding, silicone insert molding, and plastic insert molding, all of which are used to produce components for medical devices and equipment. This deflashing process can also be used with insert-molded medical parts that are produced with compression molding and transfer molding.

What’s the best way to remove flash from batches of insert molded 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 patented process. The consultation is free of charge, so send up 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 |