Sometime in the nineteen seventies or eighties when I worked for a living, my job involved making cable ties. These devices are often referred to as Zip-ties. The difference between a cable tie and a zip tie is like that between a Mercedes and a Yugo, they both perform the same function but there is a world of difference between them.

One thing that fell into my realm was determining the root cause problem of cable ties that failed in a customer’s hands. I-was lucky if I had a single specimen returned, and it was a miracle if the customer could provide the QC number. The number traced the date of manufacture, the molding machine that made it, and the batch of material that we used. Unfortunately, 99.9% of the time that information was lost.

I spent a lot of time examining the broken sample under a high power microscope. After a number of years of performing this visual autopsy I learned a lot about failure analysis. In other words I got pretty good at recognizing failure modes. The majority of fails resulted from sharp corners that became stress risers in certain environmental conditions, namely a very dry atmosphere that would dry out the nylon material. Most of these mechanical defects could be fixed by softening the sharp edge of steel in the mold cavity that produced the stress riser.

Failure analysis didn’t always point at an edge or corner. Very often the fracture point was from inside the plastic itself. Very often the fracture plane pointed toward a pin-point, like the “eye of the tiger”. About once every hundred samples I detected a black spot tinier than a spec of dust much smaller than the period at the end of this sentence.

During this same time period there were news reports on the sighting of unidentified flying objects which we all called UFO’s. It was a natural to name this cable tie failure mode as a, get ready for it, “UMO” or “unidentified molded object.”

A few times I sent the broken sample to duPont for analysis using their electron beam microscope. They would send me photos which showed the pin-point spec looking like a planet in a galaxy. They couldn’t identify the spec either.

At the beginning, using UMO to describe this specific failure mode, I had to do a lot of explaining of what it meant. The search for this critter went on beyond my days at the company. It wasn’t until the powers to be decided to totally instrument our process that we began to actually identify the conditions that existed during the formation of a UMO.

I retired in 2003 and by that time everyone in the company used the UMO term daily. All of our nylon suppliers also used the term. It took thirty years for acronym to become recognized. If you Google UMO or unidentified molded object you will find nothing like the UMO in the molding sense, and probably never will either.

Just as I never really identified the UMO’s in my universe neither have the residents of the planet Earth come even close to understanding what a UFO is, but this month the USA shot down four of them.

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