May 01, 2009
by Shane Whitaker
Because baking pans are considered to be one of a bakery’s most important assets, it is vital that it treats them carefully and gently to protect this investment. Manual pan handling can be a treacherous job, probably one of, if not the most, difficult in the plant. Hot pans can burn workers who have to remove and transport them, and these workers are also more prone to other injuries such as repetitive motion or back pain. To this end, automated storage/retrieval systems (AS/RS) are practically a necessity in high-speed bread and bun bakeries.
Many factors should be to taken into consideration to determine if a bakery could benefit from an automated pan management system. Managers must think about the quantity of pans to be stored, the frequency of changeover between pan types, the amount of time it takes to stack a load of pans and the ability to service more than one production line. "An automated pan storage system is almost always justifiable whenever pan stackers and unstackers can be configured so that one storage system can handle the pans from two baking lines," said Charles Gales, manager, automation sales, Weldon Solutions, York, PA.
Also, floor space and layout will impact the decision to invest in an automated system. "A facility with limited storage area can benefit from a multi-level automated pan storage system," Mr. Gales noted.
Automated pan management is essential for bakeries with multiple pan styles, according to Roland Lomerson, director of automation, AMF Automation, Richmond, VA. "Manually operating at line speeds of up to 40 to 50 pans per minute becomes very labor intensive and unsafe unless plants invest in automated stacking and unstacking technology, conventional or robotic," he observed.
Jamie Hankins, mechanical/systems engineering manager, Turkington USA, Goldsboro, NC, said, "I feel that a bakery should consider automating at around 8 to 10 pans per minute for bread pans and 14 to 16 pans per minute for roll pans."
The latest advances in automated pan management systems include both conventional and robotic pan stacking and unstacking equipment, as well as lasers, which are used for positioning of pan transfer vehicles on AS/RS. Also, equipment manufacturers have focused on minimizing wear and tear on pans, and PLCs and laser systems have become much more robust and faster.
Weldon Solutions continually receives ideas from customers with automated pan storage systems for ways to improve and update its equipment, according to Mr. Gales. "Our engineering department is constantly on the lookout for new technology, particularly regarding control systems. Our focus is to concentrate on areas where our customers have unplanned downtime. That is a situation that can cause compound problems throughout the operation."
LASER GUIDED. Lasers have been used for accurate positioning of pan shuttles for years, but the on-board transfer vehicle that moves loads of stacked pans in and out of storage racks was previously positioned by means of moving components, such as sensor flags or linear encoders, Mr. Gales pointed out. "These items were traditionally the single biggest cause of unplanned downtime for the entire automated pan storage system," he said.
In 2007, Weldon Solutions began designing both the E300 single-level and E310 multi-level automated pan storage systems to use laser positioning of the transfer vehicle to eliminate this problem. "The inclusion of lasers in the transfer vehicle also led to the use of a wireless transmitters," Mr. Gales added. "This reduces the number of cables that need to travel with the transfer vehicle on- and off-board of the pan shuttle."
Workhorse Automation, Oxford, PA, has updated the lasers used as distance measuring devices on previously installed systems. "The old systems were basically run with photo eyes and reflectors, and the transfer vehicle would count reflectors to know where it was at any point in time," said Ken Mentch, sales manager, Workhorse. "Today the newer systems are all driven by laser guidance, in all directions."
The photo eyes are particularly high-maintenance items — they get dusty and break — thus Workhorse modernized these systems so they feature a single laser for distance measuring, which is much faster, more precise on positioning and more maintenance friendly, according to Mr. Mentch.
Workhorse also has updated the PLC architecture of its pan management systems. "We are always endeavoring to make all of our systems more user friendly," he said. "We accomplish this through PLC programming and our HMI interface. Our pan storage and retrieval systems have been programmed to automatically recover from whatever the machine operators can throw at us. Every plant offers new challenges as to the operator’s imagination on how best to operate the system."
Its HMI interface has also been upgraded to be a maintenance tool as well as system control. Preventive maintenance prompts, exploded machine part diagrams and part numbers have been added. In the past, these items were only available in maintenance manuals, which are easily misplaced, Mr. Mentch said.
ROBOTIC SYSTEMS. Not all automated pan storage systems use transfer vehicles. The RoboCap from Capway Systems, as well as others, employ gantry robots to stack and unstack pans. The RoboCap stacker/destacker stores the pans within the system itself, according to Frank Atcherberg, president, Capway Systems, Inc, York, PA. The company has designed systems for bakeries using as many as seven different pan sets, and this system is 100 ft long.
One of the biggest innovations of the RoboCap in recent years is its patented mechanical grippers that the system uses to pick up and place pans, according to Mr. Atcherberg. Originally designed with vacuum end-of-arm tools (EOATs), the company later switched to magnets, and now it uses mechanical fingers for handling pans.
One of the major advantages to the RoboCap compared with systems that use transfer vehicles or pan trucks is that the pans do not have to be moved afterwards. "If you take bread pans, for instance, and you stack them 90 in. high and start moving them, they’ll definitely fall over," Mr. Atcherberg said. "We can about double the height of any storage retrieval system that needs to move the pans. Therefore, we are reducing floor space need for pan storage."
RoboCap features servo motors, and PLCs manage the system and can be tied into the main recipe system for the bakery. If there is a drawback to this system, according to Mr. Atcherberg, it’s the fact that the bakery needs to plan for the system up front; however, it does offer smaller systems that can be added to older lines and that will load pan trucks or automated retrieval systems.
Weldon’s PanTender and LidTender use 4- and 6-axis robots for stacking/unstacking pans, and in some cases, engineers can configure the system so that one robot rather than two can run a single line, according to Mr. Gales.
AMF recently developed a robotic pan/lid stacking and unstacking system that can be used for isolated stacking and unstacking as well as in conjunction with AS/RS solutions. It developed a lightweight, multi-magnet EOAT that provides ease of adjustment on magnet positioning and includes miss-pick detection in the event a pan or lid does not fully engage onto the EOAT, according to Mr. Lomerson.
MINIMIZING DAMAGE. AMF also provides a more conventional pan storage system, and improvements to this equipment include stack management feed and lift features, magnet head movements both permanent and electro magnet styles and magnet cover kits.
Turkington manufactures an electric pan stacker and unstacker that operates with pan trucks or an AS/RS equipment. A robotic pick-and-place style stacker and unstacker is also available. "We also offer a gantry-style system with automated storage and retrieval of pans and an inline tiered stack and unstack system," Mr. Hankins said. "In addition to the unit machines, we offer a conveying system that is modular in design, quiet and easy to maintain."
Turkington has focused on minimizing damage to pans, he added. "We use plastic modular belt in most applications because it does reduce wear and tear, is less noisy and easily maintained," Mr. Hankins observed. "We also design our controls system to aid in the reduction of noise and wear and tear on pans. Our engineering group surveyed key customers a few years ago to find out what they wanted in an automated pan system, and these were the results."
All pan-handling equipment should be designed to minimize pan damage so reglazing can be scheduled based on the number of passes a pan makes through the oven, according to Mr. Gales. "Motion of the pan shuttle is inverter controlled for smooth starts and stops," he explained. "This minimizes the chance that pan stacks fall over during transit. Inventory control of pans in the storage rack ensures that all pans are used evenly. Manual systems could keep using the same pan trucks over and over and actually send out pans for reglazing that have not been used very many times."
Workhorse introduced a new Pan Inverter-Cleaner this year. "The Pan Inverter-Cleaner combines two technologies into a single machine to provide a high-efficiency pan cleaning method for each production cycle," Mr. Mentch said. "It not only provides a thorough cleaning but also has the ability to discharge the pans upright for recirculation back to makeup or inverted for pan stacking in a more clean and stable manner."
DETERMINING ROI. The return on investment (ROI) for pan systems must include calculations for the less visible items such as repetitive-motion injuries as well as back, arm, hand and feet injuries, according to Mr. Lomerson. In addition to more obvious labor savings, bakeries have to take into consideration general safety issues, pan damage costs and inconsistent process flow that leads to lost production, he added. "Each plant has its own benchmark for capital investment rules on ROI," Mr. Lomerson concluded. "The range can vary anywhere between 1 to 2.5 years."
According to Mr. Hankins, most bakers tell Turkington USA that ROI needs to be in the 18 to 36 month range. "Each project is different, but we look at labor savings, reduction of lost product, reduced maintenance and upkeep and improved quality," he said. "Labor savings and product loss are almost always a key part of the plan when ROI is calculated."
Automated pan management and storage/retrieval systems are practically a necessity in today’s high-speed operations, and suppliers have a wide variety of systems from which bakers can choose to best suit their needs.
This article can also be found in the digital edition of Baking & Snack, May 1, 2009, starting on Page 113. Click here to search that archive.