Martha K. Raymond
Packaging machinery embodies components and subsystems from numerous technologies. For example, packaging systems consist of mechanical and electrical components, devices for sorting and sealing, software for controls, as well as material-handling systems. Though the components and subsystems are comprised of seemingly disparate elements, they still must work together to form a streamlined path for the product to move from the manufacturing floor to the loading dock.
There’s also considerable pressure on packaging manufacturers to deliver equipment that runs almost continuously and can automatically adapt to different products moving down a conveyor line. “Manufacturers are using high-speed continuously running systems instead of start-stop systems because now it’s all about throughput,” says Greg Young, engineer for Alpha Gear Drives Inc., Elk Grove Village, Ill.
The same view is echoed by packaging personnel surveyed by the Packaging Machinery Manufacturers Institute, Arlington, Va. System speed and automation, consolidation and globalization, as well as integrated systems are significant factors that will affect packaging as the industry enters the 21st century, according to the Institute.
To keep pace with these advances, components and subsystems are expected to deliver faster speeds, greater flexibility for changeover without tools, and expanded systems integration. Other demands include greater accuracy and repeatability combined with simpler, userfriendly controls. And additional enhancements are expanded robotics, self-diagnostics along with fault detection, enhanced vision systems, and expanded automation.
These and other changes are described in a report from the 4th Annual Packaging Machinery Shipments and Outlook Study Executive Summary. The report is called The Introduction of Advances and Technological Innovations in packaging Machinery, and it was compiled by Industrial Research Associates.
It’s not enough to just make systems move faster. Packaging machinery also must adapt to new packaging materials as well as different container types, configurations, and sizes. Examples include Capnew bottle sizes and shapes, a switch to plastic bottles, lighter and stronger-gauge films, stand-up pouches, new closures, and enhancements in clear labels.
A LOOK AT SENSORS
Sensors play a large role in the packaging industry. They are used in a number of ways such as checking orientation for IC direction and parts direction in a feeder. Sometimes sensors are used to detect the top or bottom of a carton, the presence or absence of labels on bottles, and printing on parts. Other applications include parts sorting and detecting along with sensing whether or not instruction sheets are included in a package.
In one application, as many as 80 to 90 bottles/min are produced, and moreover, the product changes at least twice each day. 21st Century Manufacturing Inc. (21M), Danbury, Conn., needed a low-cost and easyto- use sensor that detected the presence or absence of parts and parts orientation. The sensor would be part of a conveyor system’s inspection process, and couldn’t be allowed to slow production. “I needed a solution that was small, could be quickly and easily mounted, and easily readjusted to allow rapid changeover,” says Zsolt Toth, director of engineering at 21M.
The conveyor includes a Cap-Sure Detector, which is a modular in-line inspection system that’s placed over a conveyor. It determines whether a bottle cap is on a bottle and, if so, whether the cap is straight. At 21M, continually moving and readjusting sensors to accommodate product changeover created a bottleneck.
So, Toth chose an F-30 machinevision sensor, from Omron, Schaumburg, Ill., which incorporates a camera, lens, lighting, and processor into a compact 3 X 3 X 3 X 3 X 6 in. assembly that can be set up easily in a matter of minutes with no software programming. The camera’s adjustable shutter speed of 1/60 to 1/14000th of a second and highspeed processing of 50 msec/part lets users adjust vision systems to keep pace with production lines. “The system responds very quickly, ejecting off-line a bottle with no cap or with a skewed cap in a fraction of a second,” says Simon Yang, project engineer.
The F30 is installed on an adjustable screw on the side of the CapSure Detector and can move up or down to accommodate bottle size. The unit is locked in place when it reaches the correct height, and inspection parameters are set up in minutes by means of a five-key console. The F30’s fixed focal length is said to ensure stable, reliable detection once an application has been set up.
Easy setup procedures on the keypad include simple step-by-step instructions to ensure that the sensor detects the presence of caps on bottles and that they are positioned properly. The user enters five different parameters into the system: inspection area, contrast between background and object being detected, whether the sensor should count black or white pixels, tolerance, and the number of pixels used as the standard during inspection.
The sensor has three outputs — OK, Low, and High — for inspection. If a product’s pixel count falls within the parameters entered into the system, the OK output triggers and the product continues down the conveyor. If the pixel count is lower or higher than established for a good product, the cap is either missing, skewed, or not completely twisted on. In these cases, the Low or High output is triggered, and an air valve diverts the bottle off the production line.
“Clearly the capabilities of the vision sensor are such that we can use it in a variety of ways and for different applications,” says Toth. Some features that make the F30 flexible include a removable ring light and lens that can be replaced with other lighting systems and a standard, C-mount camera lens. Because a monitor and keypad are only required for setup, the same monitor and keypad can be used for all F30s in the plant.
Another sensor put to work on a conveyor line is a Mini-Beam Expert photoelectric sensor made by Banner Engineering Corp., Minneapolis. It senses transparent materials, and is ideal for tough sensing applications such as colormark detection on a continuous web or sensing clear bottles and wafer cassettes. The sensor uses an advanced microprocessor that differentiates between two received light levels for precise adjustment of sensitivity.
The sensor learns the light and dark conditions in Teach mode and determines the most accurate setting for recognizing these conditions. To set the sensor, a button is pushed with the sensor pointed at the target, and then once again with it pointed at the background. The sensor’s microprocessor also recognizes low-contrast conditions.
The choice of a red, green, or blue LED light source is said to give users an ideal sensing solution for maximum sensitivity to all colors, and low-contrast targets such as yellow ink on a white background. A visible red LED model improves optical sensing contrast with applications involving clear materials.
Sensing modes include regular and wide angle, polarized, convergent beam, plus glass and plastic fiber-optic types. During operation, a green indicator LED provides an accurate display of sensing contrast, so the operator knows, at a glance, whether or not the application is stable. The sensor uses an alignment indicating device, which superimposes a pulse rate proportional to the strength of the received light signal. For efficiency and convenience, one or more of the sensors can be programmed from an external switch or PLC.
A sensor that’s also useful for high speed packaging is the KT 10 contrast sensor from SICK Optic-Electronic, Eden Prairie, Minn. It reads up to 25,000 registration marks/sec. The sensor’s teach-in process technique is said to allow easy set up, where an accurate reading starts with the push of a button. The KT 10 learns by looking at the contrast between the background and the sensing mark. It then selects the proper light source for best results and automatically sets its switching threshold halfway between the background and the mark. If registration colors change, the operator presses the teach-in button. After the sensor makes its own adjustments, it resets itself to detect the new colors.
Because the sensor has red, blue, and green LEDs, it reliably reads a wide range of colored registration marks on many different colored backgrounds. The KT 10 handles difficult sensing conditions such as small marks, being able to see only part of the mark in the light spot, and having web fluctuation greater than ±3 mm. If the PLC itself cannot process readings that fast, it can be put in Run-Delay mode, and the output signal will expand to 20 msec, even with small marks.
One way to increase productivity is with sensors that offer simplified setup and reduced maintenance. An OL photoelectric sensor from efector inc., Exton, Pa., solves many problems typical of the conveyor industry by combining long range sensing with automatic calibration and a rugged, damage-resistant mounting.
The pushbutton calibration procedure, which can be used when the conveyor line is running, simplifies installation and setup. “The purpose of the microprocessor is to simplify installation,” says Ernie Maddox, product engineer at efector. The microprocessor providing the calibration capability also monitors signal strength and gives warnings of signal degradation from dirt accumulation or other causes. The status LED on the front of the unit is helpful when making accurate alignments from across the conveyor. The LED panel is slanted to make it easy to read from the side or top of the sensor. Ranges include up to 1 meter for diffuse reflection applications, 5 meters for retroflective materials, and 25 meters for thru-beam sensing. The three options mean that there is a sensor for a variety of applications.
In any conveyor application, one of the major causes of sensor failure is physical damage, either because the sensor gets hit by an object being conveyed, or someone steps on it during maintenance. One of the mounting options for the OL is a sturdy, stainless steel shield that provides protection. The shield is mounted on a 1⁄2-in. rod which allows for accurate adjustment up and down or from side to side.
A MECHANICAL MEDLEY
With the faster operation, components and subsystems produce more heat. But an SP high-speed gear reducer from Alpha Gear Drives Inc., Elk Grove Ill., helps cool servomotors by acting as a heat sink, drawing heat out of the system. “Many manufacturers are switching from dc motors and gearboxes, which were liquid cooled, to continuous-duty servomotors,” says Young. The gear reducer operates at a lower temperature than the servomotor, so the reducer draws heat from the servo. The cooler temperature lets the servomotor run faster and longer.
The SP runs up to 4,500 rpm in continuous operations, and reduces no-load running torque. The gear reducer mounts directly to servomotors running continuous-duty cycles and offers greater torsional rigidity and increased shaft loading capability,
Other components that fit well with fast-paced packaging are wrapspring clutch brakes. Compared to many torque-control devices, the CB-7 and CB-5 PAC wrap-spring clutch brakes, from Warner Electric/ Dana, South Beloit, Ill., are energy efficient and provide advantages in torque-to-size ratios. The wrapspring combination clutch brakes are said to accurately and quickly start and stop loads driven by a continuously rotating power source. A basic wrap spring consists of three elements: an input hub, an output hub, and a spring with a diameter just slightly smaller than the outside diameter of the two hubs. The spring is forced over the two hubs, and upon rotation, it wraps down tightly on the hubs, positively engaging them.
The torque generated by a wrapspring clutch comes from the crosssectional strength of the spring and is independent of speed. The greater the rotational force, the more tightly the spring grips the hubs. The clutches provide repeatable positioning within ±0.5°, and they feature a split-cam design incorporating a user-friendly spring differential adjustment for finer settings and an improved actuator for longer life.
The CB-7 is rated for 300 rpm and 1,500 lb-in. torque. It features a fast response time of 50 msec and brings loads to speed in 3 msec. Also available in a “super” configuration, the clutch lasts three to five times longer than the standard model. Designed for high-load, high-duty-cycle conditions, it uses hardened wear components, such as a heavy-duty, industrial- grade coil and a steel-tipped insert on the control collar cam. It also has a hardened and ground shaft along with wear rings fitted to critical locations. In addition, both hubs have needle bearings. The clutches are said to provide high performance and low cost while also being easy to accommodate standard sprockets, gears, or pulleys. If the clutch-brake is used in a harsh environment, then the CB-5 PAC is said to be a good choice because it’s enclosed in an anodized aluminum housing. The clutch is heavy duty, maintenance- free and rated for 750 rpm and 250 lb-in. static torque. It has a response time of 45 msec.
“Its totally enclosed, sealed housing and its food grade and grease lubrication make the CB-5 PAC ideal for foodprocessing, bottle- positioning, and manufacturing applications that must resist wash downs,” says Bill Howrie, marketing manager, Warner Electric. “It also works well in applications where friction pad particles cannot contaminate the environment, such as pharmaceutical packaging.”
If the packaging equipment is used in a corrosive environment, then Series SRD/SRDM Cylinders from Parker Hannifin’s Cylinder Div., Des Plaines, Ill., are said to be a good choice because they tolerate moisture and a variety of lubricants and solvents. The cylinder can be fitted with a rod wiper specially designed to prevent contaminants from clinging to the piston rod. With a 100-psi pressure rating, the cylinders are intended for service between 32 and 106°F. The cylinder can be used with or without the magnet for piston-position sensing. Mounts include front nose and a combination mount with front nose and rear clevis.
To keep a conveyor rolling smoothly, low-fiction, lubricationfree DryLin R Linear Plain Bearing Pillow Blocks from igus, East Providence, R.I., use a polymer gliding surface, with an anodized aluminum bearing. The DryLin line is dimensionally interchangeable with standard linear ball bearings. They feature standardized mounting hole placement and standard product dimensions for simple retrofitting. The bearings are self-lubricating, and the outside shafts resist oil, grease, and contamination. Moldedin lubricants will not wash away when cleaned. The effects of thermal expansion are reduced up to 60%.
Once a conveyor system is set up, an Accu-Adjust conveyor guide rail bracket from NoLu Plastics, Aston, Pa., simplifies incremental adjustments to the width of conveyor guide rail. The bracket features a simple press of a button for fast conveyor guide-rail changeovers. The pushbutton- activated bracket is said to meet manufacturers’ and contract packager’s needs for speed and accuracy. Unlike other, more-expensive brackets, the Accu-Adjust bracket eliminates exterior spacers, pucks, and exposed spring geometry. The sealed, ergonomic design of the bracket features a polyamide external housing that eliminates contaminant entrapment, withstands frequent wash down, and provides long-wearing durability.
MOVING DOWN THE LINE
An automatic-case sealing system has a variety of sophisticated features including fixed, random, and bypass running modes along with adjustable major flap-folding rails. The 3M-Matic 800rf random fully- automatic case sealer from the 3M packaging Systems Div., St. Paul, seals up to 8 cases/min in the random mode and up to 12 in the fixed mode. It is said to be ideal for handling a large range of case sizes.
A powered conveyor separates and holds cases that will be fed into a taping area and then centers them for sealing. When operating in the random and bypass modes, the upper flap folding and taping head assembly and the side belt box drive assemblies automatically adjust to the size of the case. Then, an AccuGlide II taping head applies box-sealing tape.
The system seal boxes up to 20 X 24 X 20 in. And, adjustable major flap-folding rails allows optimization of rail position for different boxsizes. The upper head assembly is pneumatically counterbalanced for smooth operation.
For safety’s sake, protective metal side-shields have interlock switches to shut off a machine when the guards are opened. These side shields are punched steel, enabling the operator to see what is happening inside the machine. The shields also prevent the operator from coming into contact with the internal parts of the machine while it operates.
Another type of packaging machine applies pressure-sensitive labels. The ALS 350 from Avery Dennison Printer Systems, Philadelphia, applies pressure-sensitive labels to a 3Mwide variety of products or packages traveling on conveyors at rates up to 183 ft/min. The system coordinates label dispensing speed with conveyor speed. It is available for left or right-hand attachment to conveyor lines, or as for use as a stand-alone unit. It makes instant changeovers to 16 different product/label settings, and handles large-capacity label rolls to maximize productivity. It includes a label-missing sensor, which helps ensure that every item is properly labeled.
Besides labeling and case sealing, packaging equipment often must sort a high volume of containers. To handle these tasks, a new crossbelt sortation system from Rapistan Systems, Grand Rapids, Mich., uses a powered belt conveyor on each carrier to move goods on and off in a predictable manner. As a result, a faster line speed increases the sort rate, narrower off-loading chutes can be installed, and more off-load chutes can be concentrated in a given amount of space.
The system handles a diverse range of items at sorting rates up to 17,000 units/hr with line speeds up to 500 ft/min. It can handle breakpack items such as envelopes, books, CDs, videotapes, electronic components, and heavy items weighing up to 110 lb. Other features include a modular design for fast, easy installation and modification. Its concentrated divert points allow for more sort addresses. In addition the sorter positions long parcels across two carriers and has two levels for higher throughput.