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Thinking small pays off big

High-accuracy monobloc filler/dropper tip inserter/capper at CP Packaging handles thin, softwall bottles and lightweight tips at 60/min for 3-mL containers of diagnostic reagents.
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FILED IN:  Sustainability  > Strategy
     

Small-part handling is the bane of automated packaging machinery. Tiny plastic packaging components tip easily are susceptible to destabilizing static buildup and don't have a reputation for behaving well in an automated packaging line. So when faced with filling a 3-mL bottle and depositing a 0.17-g dropper tip CP Packaging Jamesburg NJ embarked on a search for a machine that could think-and act-small. A pharmaceutical contract packager CP Packaging won a contract to fill a new diagnostic reagent product called SureStep(TM) from Milpitas CA-based LifeScan Inc. a Johnson & Johnson company. LifeScan sells its diagnostic reagent for calibrating glucose monitoring equipment used in hospitals for the treatment of diabetics. Though CP Packaging had considerable tube-making and filling expertise LifeScan's product launched in May required a dispenser that could produce a small high-precision 18-microliter drop size much smaller than off-the-shelf tubes can deliver. Such components presented a considerable handling challenge. The contract packager finally purchased a customized Modulebloc® MB 80 filler/dropper tip inserter/capper from Automated Production Systems (New Freedom PA). A mixture of standard and custom parts APS starts with a standard turret base and builds modules that are customized to a specific application. All filling tip insertion and capping occurs as containers travel around the turret. CP's machine is unique on several fronts: * Speeds of 70/min are achievable without resorting to more expensive double-track feeder bowls for tips and caps. Bottles are processed single-file but the turret is timed so that bottles are filled tipped and capped in groups of two. * There's no infeed conveyor. The 3-mL low-density polyethylene bottles weighing 0.89 g are delivered from the unscrambler bowl straight into the turret via a special delivery chute. That eliminates feeding problems and contributes to a speed increase since gravity places bottles into the turret faster than a conveyor can. * The filler's diaphragm pumps have their own control electronics for automatic self-calibration. Since the machine needs to be broken down cleaned reassembled and re-calibrated each shift the precise repeatability of the automatic calibration saves time every day. * A unique pick-and-place mechanism picks two lightweight LDPE tips while simultaneously placing two tips at the other end into the bottles. Tips are delivered to the picking end via a special intermediate turret with highly machined pockets that eliminate the need for troublesome delivery tracks outside of the vibratory feed bowl. Result: almost flawless delivery of a hard-to-handle part. * All functions occur on one compact 8'-L frame operating off a 19"-dia 62-pocket turret. CP Packaging's vp/general manager Rick O'Connell recalls the economics involved in getting the 60 to 70/min speed CP sought. "A lot of other equipment seemed to do around 50 per minute; to get upwards of 70 bottles per minute I'd have to go to a double-track system. But then the price almost doubles and the size of the machine seems to get out of hand. I was interested in a small footprint." Two-up single-file Though it's not sterile filling the machine does operate under an environmentally controlled area with a HEPA-filtered air supply. It requires only one operator. Bottles travel through the turret single-file though they are filled tipped and capped in pairs to increase throughput. The custom bottles LDPE tips and polypropylene caps are supplied in bulk by Lawson Mardon Wheaton (Millville NJ). Bottles are dumped into a hopper that feeds an unscrambling bowl already owned by CP Packaging. The bowl uses a combination of centrifugal force and vibration to track bottles around the inside perimeter. At the point of exit there's an orienting device supplied by Palace Packaging Machines (Downingtown PA) that allows bottles oriented with bottoms facing forward to pass freely. Bottles with necks facing down are detected by a sensor that triggers a mechanism to reorient at that point. At the exit bottles drop down a special chute also engineered by Palace that delivers bottles directly into the turret. Originally bottles were delivered from the unscrambler to the turret via a conventional infeed conveyor. But the bottles were so light and unsteady that they kept tipping and jamming. "Instead of having them drop through a chute onto a conveyor we decided to place them directly into the main turret" says O'Connell. "That was the only way to go. These bottles were just a disaster from a handling standpoint." The turret is stationary for the moment that the bottle drops into it. However because bottles drop into the turret faster than delivery via conveyor the turret is able to spin faster in between bottle placements. This speeding up "side effect" yielded a speed burst of 10 bottles/min according to O'Connell. Once the chute was installed CP still had to contend with occasional static buildup that fouled feeding of the lightweight bottles. "Bottles either have a tendency to cling to the wall or cling to the rods of the chute" O'Connell explains. The solution was to install a Tantec (Schaumburg IL) ionizing air gun at the chute which the operator activates only when static buildup becomes an issue. Once in a pocket in the turret bottles pass under the two no-drip filling nozzles that dive into the containers. Though the container has a capacity of 3 mL only 2.5 mL of actual product is filled. The diaphragm pump is designed to keep product separated from all moving pump parts and uses a stepper motor to provide a pumping range of .01 to 50 mL. The fill profile is programmable as well though CP uses an almost flat profile for the aqueous solution meaning it's virtually a full-on/full-off fill for maximum speed. The pumps developed by APS are unique because they automatically calibrate themselves. The operator first runs a few samples which are then weighed. The resulting weights are then entered into the pump via a separate keypad. The pump's internal control electronics (not a PLC but acting like one) determine whether the bottle is under- or over-filled and then directs the recalibration of the pump automatically. "All you do is punch in the actual weight that you have" says O'Connell "and it does the calculations for you." Such a feature is important because "with this product we have to set up this machine every operating day" explains O'Connell. "We have to strip the entire filling part down and clean any product-contact areas. Then we have to re-install it and go through a totally new set-up every day." Automatic calibration makes set-up easier. Once set the pumps provide a fill accuracy of ± 1%. A final benefit is that the pumps can be easily replaced in the event of other types of pumping systems might be required depending on future requirements at the copacker. Unique pick-and-place Bottles next advance to the dropper tip insertion station. It employs a unique pick-and-place system that doesn't rely on any external feed tracks to deliver these tiny parts onto the lightweight bottles. In a vibratory feed bowl from FMC (Homer City PA) bulk tips are tracked around the bowl's perimeter. However instead of using external tracks to carry the tips from the exit of the feed bowl tips are pushed via backpressure straight into a pocket on a two-position rotating turret which APS refers to as an intermediate turret. Once one pocket is filled the intermediate turret rotates 180° so that the other pocket can be filled. The intermediate turret acts as a pre-staging area; when both pockets are filled the picker/placer takes over. The picker/placer consists of an oblong-shaped platform on a center post that rotates as well as lowers and elevates. Four vacuum pick/place heads protrude downward from the platform two at each end. The internal dimensions of each vacuum head have been machined precisely to match the dropper tips. The symmetry of the picker/placer is such that while two tips are being picked from the intermediate turret at one end two tips are being placed into bottles in the main turret at the other. After each pick the center post rotates 180° so that the pair of tips that were just picked become the pair that are placed. The controlled nature of the backpressure as well as the precision machining of the vacuum heads and the pockets in the intermediate turrets are what allow the machine to handle the lighweight parts without jams. The pick-and-place system also eliminates the need for dual-track bowls permitting the use of less-expensive standard bowls. The next station is a cap placement and prestart station that operates identically to the dropper picker/placer. Caps which weigh 0.74 g are fed from a feeder bowl into a pre-staging turret and then are picked and placed onto bottles. After the caps are placed the picker/placer rotates them a few times so they grip the bottle threads. Next is a torquing station. There two torquing heads lower over the caps and torque the caps down. After torquing bottles exit the monobloc turret and are conveyed to labeling. Event-driven Rather than waiting for all filling inserting and capping functions to finish a given cycle before the PLC advances the turret the machine is "event-driven" meaning it relies on sensors not pre-set time delays to detect when all functions or events are completed. For example if a tip is ready to be presented to a turret that's not ready the picker/placer will wait on the turret. Likewise the turret will wait on the picker/placer if it is late. By using event-driven logic-programmed into the Allen-Bradley (Milwaukee WI) SLC 500 PLC by APS-as opposed to pre-set timed intervals it allows the machine to be much more flexible and forgiving. The machine also has upside-down and missing bottle sensing as well as missing tip and cap sensing. The machine either stops or drops bottles into a collection bin depending on the error condition. Though the machine currently runs one product and size it was chosen with a new 6-mL bottle size in mind. CP expects changeover between 3- and 6-mL bottles to take less than 2 hr. To quicken changeover the 6-mL bottle is designed to use the same tip and cap as the 3-mL bottle. O'Connell is pleased with how smoothly the machine operates and how it allows him to cut a lot of the overhead out of production. "The thing I like about this machine is that I only need one operator" he says. "I don't need to have two or three people keeping it going."

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