CONTROL AND automation advances in the food industry have seemed a long time in coming to many observers, but come they have. Don't look to be dazzled by lots of gee-whiz gadgetry. The food industry is nothing if not practical. Keeping food safe and saving money remain top plant priorities. Productivity, efficiencies, security and safety still head the list of objectives.
Nevertheless, a handful of leading-edge technologies seem perfectly adept at just that. So things such as vision systems, robotics and sophisticated networking and communications are making inroads in food plants.
An Eye on Vision Systems
“As machine vision technology has become more rigorous it has become more successful in addressing applications in the food industry,” says Nello Zuech, a consultant to the vision industry and contributor to Machine Vision Online.
“While there are many applications of machine vision in the packaging side of the food industry [newer] applications include sorting and grading,” he continues. “With advances in color cameras and the underlying ability of microprocessors to handle the additional data derived from color-based processing, more applications are being addressed. In some cases multispectral processing is now possible at the speeds required to keep up with processing tons of a product per hour.”
Inspection is a key job for vision systems in the food industry. A Cognex vision system inspects bottle caps at Original Juice Co.
In addition to being reliable and repetitive, the vision system would need to inspect at speeds of up to 300 bottles per minute. The In-Sight 5100 from Cognex, Natick, Mass., incorporates a die-cast aluminum housing and sealed industrial M12 connectors to achieve an IP-67 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.
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 sensor'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, performing the same inspection on the other side of the bottle cap.
The poster child of advanced automation is the robot, the multi-functional, programmable machine that is almost synonymous with high-tech equipment. Robots have made slow entry into the food industry, primarily due to their high cost and an old reputation for being slow.
"We have worked hard to improve our product lines in sanitary food applications, says Rick Tallian, segment manager for ABB Inc., a manufacturer of industrial robots based in Auburn Hills, Mich.
Robots have a special talent for careful and accurate handling of delicate product. Dramatic improvements in system speed, coupled with continued refinement of their pick-and-place capabilities, have enabled them to find niches in several industry segments.
"Robots are very good in picking, packing and palletizing operations," says Ann Smith, spokesperson at ABB, noting the use of robots in snack handling, cookie assembly and icing, and portioned meat handling. Credit improvements in speed, sanitary design, software and affordability for the expanded applications. Processors also are becoming more confident in robot use.
Smith reports that one pretzel manufacturer uses a robotic system to handle pretzels individually. The system, featuring the high-speed IRB 340, performs up to 150 "picks" per minute. But the pretzel maker's real productivity increase comes in the dramatic decrease in damaged product. The robot's picking capability is quick and deft.
|Palletizing is probably the top job for robots in the food industry. A Fanuc robot performs that function at Forbes Chocolate.
The palletizing system had to be capable of handling four different sizes and styles of bags and had to accommodate changes in each bag’s filled dimensions and firmness. The system also needed to be capable of palletizing the product on two different sizes of pallets and to different unit load heights. The pallet type and load heights were to be pre-specified based on Forbes’ customer requirements.
Fanuc Robotics, Rochester Hills, Mich., supplied a system consisting of its own M-410iB robot, bag handling end-of-arm-tooling, in-feed accumulation conveyor, pallet accumulation conveyor, and a push button interface panel. The system is capable of 25 bags per minute.
Many of the systems designed for food are constructed of stainless steel, which has made them sanitary, safe and effective in meat applications, particularly frozen meat patties, as well as in lunch and frozen entrée "kitting" operations.
Requirements for sanitary handling and easy "cleanability" caused robot engineers to return to the drawing boards time and time again during development of food industry applications.
"We are in the early phases of deployment of this technology in the food industry," says Tallian, "although we have multiple applications within the top five food processing firms."
Several vendors report that second- and third-generation users of robotic systems are more confident now in their effectiveness. Many start with pick-and-place then add other downstream applications, particularly palletizing.
One reason for the growth may the software. "Today's software is very operator friendly," says Tallian. "These require some pretty intense algorithms to make them work, and it's easy to take them for granted. But it's not hard for operators or engineers to work with them today."
Payback on robotic systems today is generally 18 to 24 months, says Smith, and sometimes faster. And that's "hard" payback that does not factor in the "soft" benefits of ergonomics, reduced injury-related benefits, reduced staff turnover and retraining costs that accrue to frequent employee turnover. Absenteeism is high among workers who perform highly repetitive activities. The psychological and physical drain of such work slows production even when workers remain on the job.
Robots are paired with an automated shuttle system at the Pepperidge Farm plant in Bloomfield, Conn., to deliver pans. "They have 13 different pan types at different storage locations delivering to three production lines at the plant," says Jeremy Kopicz, project engineer for Genesys Controls, a Lancaster, Pa., manufacturer of industrial control systems. "The plant has five robots operating over three lines. Pan changeovers can be done on the fly."
Previously, bread line workers pulled pans off and put them back on the lines. Today, the robots pick and stack pans. A tracking vehicle unit slides into the shuttle interface conveyor. Another car moves into the racking area where pans are dropped off or picked up. "The system reduces human labor by a tremendous amount," sums Kopicz.
Labor vs. Machine: The Payback Drama Continues
The high capital outlay required for highly automated systems poses a perpetual challenge of cost justification, particularly when important issues like job displacement are drawn to the fore. The makers of automation equipment claim that, in general, European companies are quicker to recognize the return on investment than American processors.
"We make a continuing effort to lower the cost of the equipment we bring to the market," says ABB's Smith, pointing to the improved costs of drives and lowered cost of manufacturing. "Look at a robot in the 1980s. The cost today is half what it was then. A $110,000 robot in the 1980s costs about $55,000 to $60,000 today. We have had to reduce our costs to stay competitive and to be available to all companies."
Improved software has greatly simplified robotics usage, she adds. "Now we have structured packages that make it much easier to develop a program." A software package called "Robot Studio" enables processors to develop production programs completely off-line. Changeover is often simple and quick, even when it involves significantly different products. "Often it is just a matter of changing software, or changing software and a gripper (flexible hand)," she says.
Cost Savings: A Practical Matter
Today's processors are at their most practical where cost savings is concerned. Today's automation helps control waste, ingredient usage, and energy utilization and enables real-time inventory tracking. System-wide monitoring and control is possible with Ethernet LANs.
At a major milk-drying factory in Ontario, systems provided by Tetra Pak allow control of process valves, temperature and other processing variables through a DeviceNet network. DeviceNet, a simple and low-cost communications standard for connecting industrial devices, “allows better control of the processes and allows quick modifications and expansions during the life-cycle of the factory," says Axel Andersson, manager of automation engineering for Tetra Pak, based in Vernon Hills, Ill.
"Equipment like valves and pumps can be controlled," says Andersson. "You can monitor the strokes of pumps. You can also use the systems for predictive maintenance."
While control of the processes is the main consideration, an increasingly important side-benefit is energy savings, a huge consideration in today's world business climate. Variable frequency drives, for example, are programmed to keep energy use to a minimum without sacrificing optimum processing.
Such oversight control can help reduce other types of waste as well. Jean Pierre Berlan, sales director for the Tetra Pak processing division, notes that careful monitoring of milk flow with turbidity meters following the cleaning cycle in a milk operation can deliver significant savings. "The turbidity meter lets you know where the mix [of water with milk] begins and ends so that you can at the same time secure the best product quality and optimize product losses, says Berlan.
"The dairy industry still is very conservative and the vast majority of the dairy facilities still use a timer when they flush their pipes. They are not optimizing the product recovery," continues Berlan. "The evolution of sensors is enabling us to optimize a factory far better than we could 10 to 15 years ago."A Florida citrus processing plant demonstrates how enterprise resource planning (ERP) can be effected using PLC-networked systems over an Ethernet local-area network (LAN). The end result is considerable inventory reduction.
"You can manage your business from a central control station," explains Charles Matthews at Florida's Natural Growers in Lake Wales, Fla. Florida's Natural upgraded its processing system several years ago. "And we have been constantly adding to it since," says Matthews. The ERP system is gathering critical and timely plant information that assists with planning, ordering and cost control.
"In the southern U.S., we commissioned this year a complete dairy plant where the process control is connected to the ERP system," says Tetra Pak's Berlan. "This type of set-up allows for a real-time update of production, facilitating inventory management for both raw materials and finished goods."
"To plan as accurately as possible, you need accurate information," adds Andersson.
The systems can monitor the entry of ingredients onto the process lines and provide immediate inventory and usage updates. "The ERP system will deduct ingredient taken from inventory," notes Berlan. "If you have accurate information exchange, you don't need as large a threshold of stock. Yes, you can get the information in other ways, but that is an open door to human error."