INSPECTION
Focusing On Inspection
Low-cost chips are spurring use of more accurate and faster in-line solutions.
 |
Micron PharmaWork’s blister inspection unit reinspects reintroduced blisters.
|
Inspection systems perform a diversity of tasks, ranging from simple presence or absence detection to part identification, content weighing, text and bar code checking, and leak testing. Companies have set their sights on better-performing and lower-cost inspection solutions as integral components in industry’s drive to improve quality.
Though diverse and often new technologies are being employed, in many cases they address one common need—the automated in-line inspection of 100% of product.
“The trends [are] zero tolerance for defects and [the production of] products at the lowest possible cost. In machine vision solutions, we have seen that price and ease-of-use are the driving issues,” says John Lewis, public relations manager, Cognex Corp. (Natick, MA).
“Line speeds have become so fast. When you look at many lines today, all you see is a blur of products. Virtually every product that is made in high volumes requiring high accuracy and low cost can be made better and less expensively using machine vision,” Lewis adds.
The increasing cost-effectiveness of many vision systems has prompted companies to diversify to multiple vision capabilities. “We call this ‘scope creep.’ Often end-users start off saying they want to do presence/absence and then ask ‘what else can we do?’” says Gary Kocken, managing director, North American sales, PPT Vision Inc. (Eden Prairie, MN), a maker of smart cameras.
In bringing accuracy and speed to bear on real-time data collection, process feedback, and reporting, inspection solutions support industry’s and FDA’s focus on Process Analytical Technology (PAT). PAT is a “right-the-first-time” approach, for which FDA has encouraged the adoption of new technologies for analysis and control.
VIEWING FINISHED BLISTERS
In some applications, inspection is used at the stage before final packaging to ensure that processes were accomplished without product damage.
For instance, Micron PharmaWorks (Tampa, FL) has developed a blister vision system that simultaneously inspects the tops and bottoms of punched blisters. The machine is designed for use between a thermoformer and cartoner, or it can be used in stand-alone mode. “We are providing final inspection of the blister as it exits the thermoformer, confirming that every process performed on the machine was done correctly, with an all-in-one unit running off a single PC,” says Peter Buczynsky, president.
A Scanware Lynx Spectra color camera and illumination unit inspects blisters from the bottom, just as a second camera checks lidding for print quality and registration and performs optical character verification (OCV) of lot and date codes, at rates of more than 600 blisters per minute. A reject station removes bad product, verifies removal, sounds an alarm, and stops the machine if rejection is not verified. An integrated magazine feeding system supports blister reintroduction into the line, allowing reinspection of the hand-fed product to the cartoner.
With the Visio4U machine, Uhlmann VisioTec, the Towaco, NJ-based affiliate of Uhlmann Pac-Systeme (Laupheim, Germany), provides an in-line unit for printing and inspecting blisters after sealing and punch out.
“Our pharmaceutical customers are concerned about quality improvement and high manufacturing and packaging costs and frustrated about low efficiency. We have tried to answer those concerns with Visio4U, which closes the last quality gap—the verification of the tightness of blisters after they have been produced,” says Christoph Lehmann, VisioTec sales manager.
Visio4U combines leak testing, blister inspection, printing, and print inspection in one machine for final quality control before secondary packaging.
Companies achieve 100% blister cavity inspection with the VisioLeak component by VisioTec partner Wilco AG. Costs inherent in statistical sampling and techniques such as blue dye testing are avoided. “Until now, people have had no choice for testing leaks in-line. Traditional leakage inspection is messy, time-consuming, and inaccurate. When a defective blister is discovered, a company might take 10,000 blisters between two samples and destroy them,” says Lehmann.
In VisioLeak, a mechanical sensor discovers the presence of leaks and gauges their size by measuring the force of the expanding blister foil in a vacuum. “Blue dye testing is a subjective measurement of the presence of dye in the cavity. And you can’t find pinholes smaller than 35 to 40 µm. VisioLeak qualifies leaks at the 5- to 10-µm level,” he says.
The machine also features a HAPA drop-on-demand digital printer system for printing on the individual blisters. By eliminating top-web printing before sealing, lines run more efficiently, and print damage that can occur during sealing is avoided, says Lehmann. The approach supports late-stage customizing, where only blisters that have passed inspection are printed with product-specific information.
A VisioChrom camera system checks for defects from the bottom side of the blister. Nondefective product is then printed. Finally, lidding print is inspected with the VisioRead OCR (optical character recognition)/OCV camera.
For other machine vision applications, more cost-effective and powerful processors have made it feasible to implement multiple inspection stations at various points on and off the line. Sensors might be deployed for in-line checking at stages of filling, capping, and labeling, and even after product is in the cartoning and pallet-loading stages.
“End-of-the-line inspection systems can do a great job at final inspection, but waiting until after an item has undergone numerous value-added stages of production can often mean costly and time-consuming rework of a bad product,” says Cognex’s Lewis.
“By distributing vision at more points in the process, manufacturers can respond more quickly to equipment problems and achieve better process control. With Ethernet connectivity, multiple vision seniors can be centrally managed, making results data more accessible to all levels of the enterprise,” Lewis adds.
Industry is trending toward smart cameras and systems where CPUs reside in sensors for image processing and analysis. In Cognex’s solution, image processing occurs in the vision sensor, supporting a distributed processing approach.
“Smart cameras and vision sensors are proliferating because they are easily scalable. For a few thousand dollars, you can add a new sensor with a processor in every camera. With vision processing linked from a single PC processor running multiple cameras, scalability can be more limited,” says Lewis.
“The trend is toward smart cameras and vision sensors. Microprocessor technology has become powerful enough to run meaningful algorithms, in more compact form factors,” says Pierre Boriero, product line manager, Matrox Imaging (Dorval, Quebec, Canada).
Matrox’s new Iris E Series is a line of configurable smart cameras powered by an ultra-low-power Celeron Intel processor, running the Windows CE.net operating system. The E Series supports the Matrox Imaging Library that integrators can use to develop applications without the need for traditional programming. Managers configure cameras using the Design Assistant Interface, which features a flow chart–based approach.
“The E Series features the flexibility of our PC-based vision systems. It runs the same software tool kit around the same programming interface. We have also introduced the ability to read and grade 2-D bar codes to standards,” says Boriero.
Smart camera and sensor vendors offer graphical point-and-click interfaces for configuring tools and managing inspection processes. Using intuitive interfaces, users can select and set inspection tool parameters, monitor and manipulate camera images, manage multiple networked cameras, and export information to plant and enterprise level systems. Managers can develop custom interfaces for operators on the plant floor.
Supporting its Impact family of high-speed smart cameras, PPT Vision offers enhanced software (Release 6.6.0) for its Impact suite of inspection tools. Tools perform functions such as pattern matching, measurement, defect detection, and character reading. An upcoming Release 7.0 features a new navigation and routine interface, with enhanced application accuracy and speed, says Kocken.
“We like to call our smart cameras intelligent cameras. For high-speed applications we are providing very sophisticated, yet easy-to-use algorithms that in the past you would find only in PC-based systems,” Kocken says.
With the Vision Program Manager (VPM), a graphical point-and-click environment, users program tasks, and organize them in the order they want them to run. Programs are imported via Ethernet to the camera’s flash memory. “Once the camera’s logic has been created on a PC, you save the program to the camera’s internal memory, then disconnect the Ethernet connection, leaving the camera to run in a headless environment.” With Impact’s Control Panel Manager (CPM), users build a custom control panel interface for viewing the camera images and results. “The actual camera image is configurable. You could show thumbnails of the last 50 rejected images or tables with pass/fail results, in a less limited environment than is presented to operators,” Kocken says.
For those who want to get up and running quickly, PPT Vision is offering Impact KickStart software. KickStart is a nonprogrammable interface designed to handle 80% of typical machine vision applications.
KickStart will be included with PPT Vision’s A10, a low-cost camera launching this year as an upgrade alternative for vision sensor users in the market for enhanced inspection capacity. “If you are just checking presence/absence at slow speed, then you don’t need the horsepower. This camera will provide a higher-power algorithms for more control over noise variables such as position variations and changes in product and environment intensity.”
For cost performance, the A10 uses a high-speed dedicated chip that integrates the CPU with Field Programmable Gate Array technology. “We can use this powerful embedded device on one chip to put a high-performance vision system on one board. This allows us to do high-performance inspection at a very low cost of goods manufacturing. We are addressing the need for a low-cost smart camera that is capable of using an industry-proven high-level CPU for running complex algorithms. This will cover 80% of what people do with a smart camera,” he says.
PC-BASED OPTIONS
Speed requirements and a diversity of inspection tasks are factors that affect the choice of whether to use a PC-based system or smart camera. One advantage of PCs is that they are more easily upgraded when new higher-performing chips become available, says Kocken.
“PC-based vision systems are fully programmable. As a result, they are more easily tailored to specific applications. But they also require programming knowledge,” Lewis notes.
Optel Vision (Quebec City, QC, Canada) makes PC-based machines for checking package integrity, verifying codes, and inspecting blister packs. Pierre Turcotte, regional sales manager, says that Optel Vision offers turnkey solutions that obviate the need for third-party component integration. They are easier to validate than smart cameras and sensors.
“We can tweak our general processing algorithms to meet the exact inspection requirements for each application. Once smart cameras are installed and integrated on a line, maximum efficiency is difficult to achieve. We can maximize system efficiency and thus minimize false reject rates,” he says. Optel Vision uses the Windows XP operating system based on modular architecture. This allows easy integration of multiple inspection components, such as cameras, sensors, and bar code readers. “We have a camera system that carries out real-time on-line OCV bar code inspection and linear and 2-D bar code grading to ISO/IEC standards all at the same time,” Turcotte adds.
Cognex has started shipping ProofRead, an OCV system using OCVMax for character verification on flexible containers and curved or distorted surfaces. OCVMax, based on PatMax geometric pattern-matching technology, supports greater tolerance to perspective changes and to random spatial distortions that can occur while printing on moving objects. Besides addressing package contour changes, ProofRead tolerates distortions created in the printing such as from misalignment of print heads or when line rates and marking systems are not properly synchronized. ProofRead provides an intuitive interface for task configuring and a touch screen interface for operators.
A new proofreader solution from Mnemonics Inc. (Mount Laurel, MD) is geared for inspecting large clinical trial labels. In the Avia Label Inspection system, Mnemonics has transplanted its Avia proofreading solution to an in-line system. Besides proofreading and checking print quality, the system performs OCR and OCV on variable content.
“It’s the same Avia software engine reformatted to work in-line, so there are no additional validation issues. A larger camera handles inspection all at once on labels up to 6 × 10 in. in size. Content varies with each clinical trial label, for instance, so we are interfacing with the printer to reconfigure our system for each label,” says Michael Negin, president.
“The current technology for inspecting clinical labels is human beings. Our performance rate provides a 99% reduction in human labor,” he adds.
Sidebar: Inspection through Infrared Imaging
|
Mnemonics has also launched the Avia Insert Counter. A high-resolution camera and mega-pixel lens package captures and inspects boxes of inserts up to 24 in. long and up to 12 in. wide in a single large field of view. Boxes with up to 2000 inserts can be counted. Insert counting times are under a half second.
“There is no solution that can handle this range of box sizes with one camera, in one enclosure, without the need to adjust the camera, lens magnification, or focus,” says Negin. Operator use is simplified with automated visual location of boxes and automated set up of scanning lines. Job changeovers are accomplished in under 30 seconds, and new jobs can be set up in less than five minutes.
PARTICLES AND WEIGHTS
Novo Nordisk and Aventis have adopted CVT inspection machines from Moeller & Devicon A/S (Sandved, Denmark), a Bosch Packaging Technology company. The units employ Slitec Sliding Image Technology vision-based technology for particle inspection in liquids in glass containers, such as vials, syringes and ampules, says Eric Isberg, product manager, pharmaceutical liquid products, Bosch Packaging Technology (Minneapolis, MN).
A handling system loads containers into a carousel, where they are spun at high speed and instantly stopped just prior to inspection. As the contents continue to rotate, the PC-based vision system compares frames to identify the shifting position of particles. Virtual frames divide the camera window, each taking an image of the container. Images are analyzed and compared for the presence of particles. Inspection results from two independent cameras are then compared and must agree. False rejects are minimized as containers with two inspection results are automatically refed and reinspected.
Supporting inspection of 200 to 600 containers per minute, CVT series machines use servo-driven infeed scroll and star-wheel infeed systems, says Isberg.
“Each carousel station has its own servo drive to precisely control the motion of each vial. When inspecting the containers, Slitec technology eliminates back scatter, accounts for scratches on the glass, and can recognize objects such as cartridge mixing beads,” Isberg says.
For weighing liquids and lyophilized product, Hospira and Eli Lilly have installed a BOC Edwards noncontact checkweighing system marketed by Bosch that employs nuclear magnetic resonance (NMR) technology. One hundred percent of vials are weighed without contact or disruption at line speeds of up to 600 per minute. In stand-alone or in-line mode, the technology requires a transfer system that sends product at very controlled speeds for accurate measurement, says Isberg.
In NMR, a radio-frequency magnetic field is pulsed with a probe to premagnetized vial content. The pulse distorts the vial’s magnetic field. The same probe receives a signal emitted when the magnetization returns to equilibrium. The amplitude of the signal is proportional to the number of hydrogen atoms present and therefore used as a measure of the mass of the vial contents.
Omron Electronics (Schaumburg, IL) also offers vision sensor solutions, calling itself a one-stop shop. “One of our strengths is that we are in a position to provide a turnkey solution—the vision system, the PLC, and the HMI interface. We have an in-house system integrator—Omron Manufacturing of America,” says Carlos Melo, vision and sensors product marketing manager.
Omron’s latest product is the ZS laser displacement sensor. Attributes such as thicknesses of pill coatings and liquid levels are measured based on the angle of refraction of an emitted beam. Combining laser measurement and CMOS imaging, the ZS is suitable for measuring transparent targets such as pill coatings and the thickness and diameters of glass probes, says Melo.
In entry-level vision sensing where high speeds are required, the ZFV smart vision controller and camera supports diverse inspection tasks including presence/absence, label positioning, text characters, and bar code completeness and dimensions. The ZFV benefits from advanced algorithms that enhance detection of product attributes, says Melo.
In the medical device arena, Baxter Health Care (Mountain Home, AS) has adopted the MedaScope x-ray imaging system from Glenbrook Technologies Inc. (Randolph, NJ). MedaScope uses proprietary MXRA x-ray imaging with a uniquely designed phosphor scintilator and optics system. It provides higher resolution than traditional fluoroscopic x-rays. MXRA also responds to the low x-ray voltages that are required for inspection of low-density materials, says Gil Zweig, president.
Baxter is inspecting the molded hub and lumen components of Alyx blood collection systems. “Prior to the installation of the MedaScope, production operators had to cut open the hubs to verify proper placement of the lumens. This destructive testing was costing Baxter hundreds of thousands of dollars per year,” says Zweig.
