Total Quality Inspection of Juice Bottles after Filling Process
Original Juice Co. found itself with a challenge when it came to achieving consistent results in the placement of a bottle cap onto a product bottle after the filling stage. It wanted every bottle cap that gets twisted onto all of their different product bottles to be applied fully, to be applied straight and not skewed, and to be sure that the tamper-band is not broken on those particular products that require one.
The company looked to install a state-of-the-art vision system that could inspect a variety of imperfections not tolerated on high-speed lines and filling equipment. The shoulder strength of the various bottles is very important and must withstand significant head pressure and torque in capping and filling stages of operation. Any defect that could compromise the integrity of this area is an inspection attribute of the vision system.
In addition to performing reliable and repetitive applications, the vision system chosen would need to inspect at a high-speed rate of up to 300 bottles per minute to accommodate the high production requirements of Original Juice Co. To address this, Original Juice Co. began working with SciTech Pty Ltd, which has a long history of machine vision experience as a Cognex Integrator.
The process began with SciTech performing an on-site trial. The results met the satisfaction requirements of all involved and proved that this project was feasible and would be of enormous benefit in ensuring that every bottle leaving the Original Juice Co. plant is entirely free of imperfections. The trial focused on one bottle product only. On conclusion of the trial period, work began on implementing a full system that would cater to all current bottle products and also be scalable in order to accommodate any new bottle and cap types in the future.
SciTech chose to use the industrial-grade In-Sight® machine vision system from Cognex. In-Sight vision systems are the highest performance models of the industry-leading family of In-Sight vision systems. SciTech was confident in choosing the In-Sight vision systems to satisfy the inspection requirements involved.
The In-Sight vision system incorporates a die-cast aluminum housing and sealed industrial M12 connectors and achieves an IP67 rating for dust and wash-down protection on the factory floor. These environmental attributes would prove to be crucial in withstanding the wet, citric-acid environment of the inspection site as a result of the juices produced as well as the cleaning chemicals used in the area.
This also required that the fixtures and fitting to be built using only stainless steel material.
Two cameras are better than one
The overall system consists of a touch-screen industrial PC incorporated into a stainless steel enclosure. The enclosure also houses the Ethernet hub, the digital power supply of the lights, a PLC and various power distribution components. After bottles have been filled and capped they travel down the conveyor line, where two cameras sequentially inspect the bottles.
The first camera looks directly at one side of the bottle and inspects the bottle cap at this side only. A red LED backlight provides the camera with a silhouette image of the bottle. Back lighting provides maximum contrast between the product outline and its background and is ideal for measuring external part edges. This results in images that work extremely well for the vision system's measurement and inspection tools.
When the bottle comes within the camera's field of view, a sensor is triggered and an image is taken. Cognex In-Sight vision software tools then analyze the image for defects and determine whether a bottle is flawed or not. In the event of a failure being detected, a fail signal is sent via one of the camera's outputs to the PLC. The PLC then triggers a reject mechanism, which removes the bottle from the line. After passing the first camera, the bottle will travel a little further before the second camera acquires another image of it.
The second camera, mounted similarly to the first camera except at the opposite side of the conveyor, focuses on the other side of the bottle cap. The same inspection criteria apply equally to this camera. All defective parts are knocked off the conveyor line into a reject bin. A red beacon also becomes illuminated for 5 seconds when a bottle defect is noticed, notifying the operator.
Good parts are simply allowed to continue unhindered on the production line. During this inspection a pattern of lines is projected onto the bottle cap and bottle, and the vision system is used to detect any deformity in cap height on the bottle, cap presence or absence, tamper-band presence and quality, and cap skew. To complete these tasks the vision system uses edge detection and histogram software to measure the cap, analyze the angle of the cap and determine cap presence.
Because of the number and variation of bottles involved, the system would need to be able to accommodate easy product changeover. The mechanical fixturing was designed with this specific requirement in mind. The cameras, backlights and sensors were mounted onto one fixed bracket that could be moved vertically via a turn wheel by the operator to accommodate the different height requirements of the bottles involved.
The changeover procedure requires a height-determining tool to be temporarily attached to the fixture. Using a turn-wheel, the operator screws the tool down to a position whereby the tool rests gently on top of the bottle lip. When the tool rests on top of the bottle lip, the correct camera/light/sensor position for that product has been set. On completion, the operator removes the height-determining tool from its slot.
The final step in the changeover procedure is the operator makes a selection, via a custom application, using touch commands on the computer's screen. This screen uses a tab-style interface to segregate the different bottle types appropriately. Each tab has a descriptive name indicating the different bottle categories.
On selecting the appropriate tab to the bottle type being run, a corresponding button appears that when pressed loads the correct vision file associated with the new product being run on the line. On successful completion of this step, the main software interface screen will contain the descriptive name of the bottle type selected. The changeover procedure is now complete and the line is ready to run.
When the line is running, a custom application on the VGA touch-screen monitor shows the last failed image acquired from each camera. The cameras also FTP their data back to the PC which is stored in text files. This provides Original Juice Co. quality engineers with more information about their process.
The vision system's key asset is preventing defectively sealed bottles from being shipped to customers. Most importantly, the vision system has ensured that every bottle leaving the Original Juice Co. plant is free of imperfections. This has allowed Original Juice Co, to adhere to their pledge in high-quality products.
About Golden Circle/Original Juice Co.
Golden Circle's main factory is located at Northgate, a northern suburb of Brisbane. Golden Circle also owns the Original Juice Co. plant at Mill Park, on Melbourne's northern outskirts, and a fresh fruit packing operation in Griffith, NSW. Sales offices are located in every Australian state and New Zealand.
Golden Circle is an unlisted public company proudly owned by 700 Australian farmers. These farmers, plus others, supply more than 180,000 tonnes of fruit and vegetables every year to the factory for processing. The fruit crops, of which pineapple is the largest, come from the Sunshine Coast hinterland, Maryborough, Yeppoon and further north and the vegetables largely from the Lockyer Valley region, south-west of Brisbane. Crops not grown in Queensland are sourced from southern states.