Wednesday, December 30, 2009

Cryogenic Material Recovery

A few weeks before Christmas, we completed a job for a Worcester-based company using our cryogenic material recovery service. Our customer manufactures and sells safety devices with a very special purpose. These particular parts are used to save someone from drowning after he or she falls through thin ice. The person simply needs to slam the device into solid ice surrounding the hole that he or she fell through. This will keep the person from flowing under the ice or even drowning.

Our customer had several thousand of these safety devices with defects. He had been saving them over the years trying to figure out what to do with them. The part has a plastic casing that is molded around a steel pick and spring. Many of these parts had defects from the molding process such as mold shorts. In addition, some of the steel picks were misaligned when they were molded. Our customer wanted to recycle as many steel picks and springs as possible from these safety devices. His plan was to use these parts in future molding runs. We were happy to help our customer using our cryogenic material recovery service.

We experimented with some sample parts to find the best method to remove the plastic surrounding the steel picks and springs. In the end, the best method involved heating the parts up and then submerging them in a liquid nitrogen bath. This large temperature deviation caused the plastic to crack and shear off of the steel pick. Since there was some variation among the safety devices, a few of the steel picks still had some residual plastic. Our customer told me that he had enough clean steel picks to finish the next molding run. He was quite enthused with the results.

Below are pictures of me lowering the safety devices into the liquid nitrogen bath after the parts had been heated. The second picture shows nitrogen turning from a liquid to a gas as it boils off inside the container holding the safety devices. The last photo shows the picks after our cryogenic material recovery service had been completed.









In the past we have completed many cryogenic material recovery jobs. Customers come to us to recover specific parts of a complete assembly. Typically, we will complete trials on some assemblies to find the best method to remove specific parts. The two most common processes involve utilizing our cryogenic processor for several hours or a liquid nitrogen bath. If you are trying to recover inexpensive or highly valuable parts from an assembly, let us take a look at your application. Please send an email to rtaylor@nitrofreeze.com or call 508 459-7447.

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