Video: Pez Dispensers and Porcupines

Supplied by Glebar, the video above depicts a through-feed grinding, inspection and packaging cell that was the subject of this April-issue article. Such footage makes it easy, in my view, to get lost in watching the parts proceed through multiple feeders, conveyors and processing stations. It’s even easier to forget the amount of work that goes into manufacturing automation, which, as in this case, often resembles some kind of twisted Rube Goldberg machine.

For this particular cell, engineers from Glebar spent a significant amount of time working with their customer to figure out how to separate bulk-loaded parts for individual, pre-machining inspections. Although required to ensure zero defects, these inspections couldn't disrupt the two-part-per-second production rate. Problem was, the parts were too small and too brittle for traditional means of conveyance through the inspection stations, which consisted of a laser diameter check for ovality and a high-speed camera inspection for voids and defects.

The team's first plan was based on another system that was developed to inspect roller bearings. Parts would be dropped individually on a track consisting of two parallel rollers that spin to send the parts spiraling along. The gap between the rollers would be precisely sized to ensure any significantly out-of-round parts drop through. The rest would be measured via the laser and possibly high-speed camera as they corkscrewed down the track.

In practice, however, this system would have proven less than ideal because the parts are top-heavy. “The nose end was heavier and (the parts) would want to stand on-end, but we needed them to lay flat,” recalls John Bannayan, president of Glebar. “If we’d have spent more time, maybe it would have worked, but we just didn’t think it’d be robust enough.”

What does all this have to do with Pez dispensers and porcupines? These are the team’s nicknames for the systems that solved the problem. Both can be seen in the video above. The “Pez dispenser” dispenses parts one at a time in a manner very similar to its namesake. From there, the “porcupine” (upside-down conveyor) carries them through the inspection stations.

The article offers more detail on how these systems work and other challenges the team faced (such as avoiding the need to rotate the part within the laser beam for the ovality check). Meanwhile, I think it’s worth conveying a little bit of the background on how the solution came together. After all, it’s easy to take technology for granted, not to mention the human thought and effort behind its implementation.