By Carroll McCormickMachinery and Equipment Maintenance Test and Measurement
Late last summer, after a lot of getting nowhere trying to fix a problem with a bottle capper at GlaxoSmithKline – a pharmaceutical company in Mississauga, ON – maintenance used a $300 digital camera with a high-speed video function...
Late last summer, after a lot of getting nowhere trying to fix a problem with a bottle capper at GlaxoSmithKline – a pharmaceutical company in Mississauga, ON – maintenance used a $300 digital camera with a high-speed video function to slow down the action of the machinery, study it and then solve a previously invisible problem.
“We found a lot of inaccuracies that were not evident to the naked eye,” says Dale Archambault*, manager of maintenance and reliability, GlaxoSmithKline.
At a real-time capping rate of one pair of bottles every 1.8 seconds, give or take a few milliseconds, nothing could be detected by eye that explained why the capper was screwing down some of the caps too tightly and others too loosely; the action was also too fast to accurately correlate the instructions in the computer programming ‘recipe’ to the many steps in the capping process.
But shooting videos at 240 frames per second (fps) slowed the action to just one-eighth real time, allowing maintenance to easily observe a worn and wobbling spindle and a cap gripper that activated too late and released too late. Only the slow-motion videos let maintenance see that two bottle brake gauges differed by 4.5 bar, allowing one of the bottles to be released too soon, spin and therefore affect the capping torque.
“We tried for the longest time to fix this before we got the camera. We made assumptions and tested theories, but we didn’t get anywhere. We noted the spindle wear before, but we didn’t think it was significant enough to be an issue,” Archambault relates.
Glen Schultz*, improvement leader, GlaxoSmithKline, adds, “Without the high-speed camera, I would have never been able to see that the two gauges were different.”
Video footage of the repaired capper also made it a breeze for maintenance to demonstrate to the quality department that the problem had been fixed and to explain what they had done to prevent a recurrence of the problem. “The video gave clear evidence that we made an impact on the [production] quality,” Schultz comments.
The marvel was not the use of a high-speed video camera per se. After all, maintenance already had a high-speed camera with a 512 MB memory card and a VHS recording tape. But as Schultz explains, “We’ve had this camera for years, but everyone tends to avoid using it because it’s very cumbersome to set up.”
The breakthrough was in connecting the availability of inexpensive point-and-shoot cameras that can take high-speed videos with the problem they were working to solve. They are dead-easy to use and the videos can be reviewed on the spot using the camera’s display screen. They can be quickly downloaded to a computer for more leisurely viewing and sharing with colleagues.
As the struggle to troubleshoot the capper dragged on, an equipment engineer told Schultz of a $130 digital camera with a high-speed video capability that he had purchased during a blowout sale at a big box electronics store. Schultz and two engineers test-drove the camera and found that it did a good job of capturing the capping process.
“I quickly realized the benefit of having a camera like this,” Schultz relates. “At the beginning of the investigation, we were looking into buying a more expensive unit; they started at about $5,000 and some cost over $50,000. Because of the experience with the $130 digital camera, I did extensive research and learned to get the most out of the camera and obtain a premium-quality high-speed picture. I then purchased a slightly more expensive model that had a few extra features, including a 12.5x optical zoom, at a minimal price difference.” (See sidebar below.)
Schultz also bought a special memory card designed to handle high data transfer rates without causing any lag or freezing while capturing or reviewing high-speed videos. In addition, he purchased a dimmable LED light unit, as good lighting becomes an important issue at higher fps speeds.
“I preferred the dimmable feature because I could quickly control the lighting instead of increasing or reducing the exposure setting in the camera. I also used a regular flashlight in some situations and it worked great.”
The new camera Schultz bought could shoot up to 1,000 frames per second (fps). For the capper, he found that anything less than 240 fps was not fast enough and anything faster was not necessary. Too, as the fps rate increases, the image height decreases; more speed just for the sake of speed comes with an unnecessary reduction in the image size.
For solving this problem, everyone at GlaxoSmithKline judged the camera to be a success. “I told the head of global engineering that this was the most valuable maintenance tool to come along in years,” Schultz recalls. “Because of the testimony of what the camera did to assist with the investigation, the company has purchased three more cameras for other production areas.”
Beyond solving the capper problem, Schultz has used the camera to study a problem with wrinkled labels on bottles. His thinking is so fresh on possible applications that in a little brainstorming conversation, he quickly cooked up some ideas on incorporating slow-motion clips into a computerized maintenance management system – for example, storing video clips directly in the CMMS, inserting links to folders elsewhere in the company’s computer network, or simply inserting a line of text that tells any readers where to go to find video clips associated with a piece of equipment.
Schultz adds, “We could time the actions of a process, time the dispensing of blister packs onto a conveyor, or see the tablet release from a tablet press … the possibilities are endless.”
Carroll McCormick is the senior contributing editor for Machinery & Equipment MRO. *Note that the employee names used are not their real names; they were changed to comply with a privacy request from GlaxoSmithKline.
Carroll rates the image
GlaxoSmithKline let me review some of its video footage: One 45.5-MB clip rolls for one minute and 11 seconds and shows five pairs of bottles going through the final screw station. If you are curious to know by how much you are slowing down the action, divide the fps rate by 30 to calculate how much longer it takes to present the real-time action in slow motion; i.e., 240 fps/30 = 8. You now have eight times as long to view the real-time action. Put another way, the action is being slowed to one-eighth real-time.
The lighting quality is excellent and the depth of field (the amount of the scene that is in sharp focus) is remarkable.
Good depth of field is critical for this application; the more you have, the more of the equipment you can properly see and study. This also relates to the occasional need for good artificial lighting. Skipping a technical explanation, the more light you have, the more depth of field you get at a given shutter speed – or fps setting – at the proper exposure. If you increase the fps and keep the lighting level constant, however, the depth of field will drop. As it decreases, the amount of nearer and further away detail that is in focus also decreases; this quickly results in wretched close-up photography.
Keeping in mind that this is not meant to be a competition with National Geographic-level photography, although the video is remarkably crisp and not very grainy. Even enlarged to the full height of my 27-in. monitor, the graininess is no impediment to seeing fine detail, right down to the letters stamped on the spindles.
With my trigger finger on my mouse, I could start and stop the video seven times a second. For even better split-second viewing control, you can drag the action back and forth with the mouse. How could you say no to that opportunity?
If you want to try this yourself, you can check out these products:
• Camera: Casio EX-ZR100 ($300).
• Memory card: SanDisk 8GB Extreme Pro ($50-$60).
• Light: Camlite VL-144 5600K LED Video Light Kit ($250-$350).