This ran originally in PMPNews.
By Dave, Vaczek, senior editor, Design News
Moynihan adds, "Optel brought a lot of experience in automated blister inspection to the design of the slat-filling solution. There are a lot of systems on the market for camera-based blister inspection, but very few for inspecting slat fillers. We worked closely with them in developing the solution for our requirements."
System on slat fillers
The plant is qualifying the vision system on five Merrill (IMA) slat fillers. All the machines are being qualified for the full range of bottle sizes and tablets packaged at the facility, which include the Centrum vitamin product line. The first system required almost a week for installation, then a week of recipe development and testing, followed by a week of installation operation qualification (IOQ). "After the recipes for the first two lines were developed, they could be moved from line to line, so we are now doing the install, recipe development, and OQ in two weeks," Fuchs says.
The Slat Filler Inspector inspects for numerous tablet defects including broken and missing tablets, and monitors the number of doses filled into the bottles. The PC-based system processes images captured by cameras arrayed along the plant's 990-mm-long slat fillers. Ten cameras are each assigned a discrete number of slat cavities and bottles in providing a complete view of the slat loading and bottle-filling operation.
"The system has to verify that all cavities are filled. It basically counts every cavity by taking a picture of it. If you have an empty cavity, it will identify that as a short count and the bottle will be rejected," Moynihan says.
Identify incorrect tablet color or shape
The system can also identify incorrect tablet color or shape, and the system automatically shuts down, and shows the operator the fault's location, allowing for manual removal. The bottle in question is rejected. "Tablets with slight variations in color previously undetected by manual inspection are now indentified, The system differentiates the lightness, picks it up as a fault, and rejects the bottle."
Optel developed algorithms for identifying partial tabs hidden in the cavity by full tabs or sitting atop full tabs, sticking out of the cavity but still trapped. For this measurement, the depth of the tablet in the cavity is assessed using color and lightness analyses. "An operator would never pick that up. We weren't expecting [to have that function]," Moynihan says.
The system is flexibly reset for supporting new bottle sizes and counts as well as new solid dose products. A recipe change for a different bottle and count is accomplished in under five minutes. "If the product changes, the process becomes more detailed. We have to challenge it against our other products, and set new inspection parameters," Moynihan says.
Recent advances in camera, lighting, and image processing technology have made vision systems cost effective for bottle filling applications, yielding a better ROI, says Louis Roy, president, Optel Vision. "We have transferred the knowledge and tools we apply in blister inspection to the slat filling solution," Roy says.
The price/performance of the Slat Filler Inspector's PC is enhanced with an Intel Quad core processor. Ultra bright white LED lighting supports the analyses of contrast and shadow. The integration of the vision system highlighted a need for improved slat filling. Some of the slat cavities were too large to keep the tabs stable for capturing good pictures. Pfizer acquired new slats from IPS (Denville, NJ), Fuchs says.
Efficiency is critical
The engineers are evaluating the system's impact on overall equipment effectiveness (OEE). "We know our efficiencies have gone up considerably. When you have operators doing manual inspection, you have a lot of minor stops. These have been eliminated as the system keeps running, rejecting out-of-specification bottles," Moynihan says.
"Whenever you put a new process in place, it affects other processes. We have identified some issues with broken tablets that we are trying to correct in the manufacturing process," he says.
Batch sizes of upwards of 3 million tabs might have hundreds of broken tabs. "That is a small number of broken tabs, but you have to reprocess bottles rejected for one broken tablet. This creates a rework loop. We are evaluating the OEE implications in this area," Moynihan says.
The plant is seeing positive results, the engineers say. In OQ testing, finished bottles were checked for defects. "In all the samples we ran through validation and testing we have yet to find a broken piece of tablet in any bottle. The system is exceeding our expectation thus far (in detection of broken tabs)," Moynihan says.
The team is evaluating areas for cost savings beyond the phase out of inspection personnel. Initial soft savings derive from increased line speeds and output, Moynihan says. "This is a new process, and we have the new process step of rework, but we hope to identify additional areas for savings this year," Moynihan says. "Another new benefit is that we are deriving new value from existing equipment by marrying new technology with proven technology."
Are other Pfizer bottle filling facilities interested in automated inspection? "We've had visits from other Pfizer sites that are evaluating it on a site-by site basis," Moynihan says.