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In Focus - February 2010
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Adaptive handling systems provide dynamics and profitability if comprehensive ranges and frequent changes in assortment are given.
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With a flexible handling system various packing processes can be efficiently organized.
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Adaptive handling systems make packing and palletizing plants flexible.
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02-01-2010 -
Every week a new product generation replaces the previous one. These products, which provide new impulses in trade, are a real challenge for the packing process. Faster, process reliable, and flexible automated solutions are in constant demand. They help to keep the handling costs under control, even at an increasing product variety.
Times have changed. Products can no longer be designed and packaged in the same way for long periods of time because consumers have so many selections to choose from. The packaging industry is constantly changing their designs, in order to present the buyer with a better product. Thereby efficient automation is getting more and more important. Whereas a person in an eight-hour shift, can pack up to nine tons of goods, automated plants move about 60 tons per hour, even with various packing materials and flexible layer patterns. A high performance plant with two so-called layer-forming and palletizing robots palletize about 266,000 tons a year!
The selection of the palletizing type depends on many features
Individual automation concepts differentiate, depending on the industry, packaging, quantity as well as the size, weight and quality of the article. If low quantities of ten to fifteen units per minute are handled, usually multi-functional grippers are used for handling pallets, intermediate layers and products. Pallet supply is provided by lift trucks and fork lifters, or by a pallet feeding system.
In case of medium-sized volumes between 15 and 40 units per minute, the multi-functional grippers can be upgraded in such a way that several units with different sizes can be mounted. Compared with a smaller plant, the travelling time remains the same. By using a "Multipick", a simultaneous mounting of several products, efficiency is increased without involving higher capital investments.
In case of larger quantities between 40 and 100 units per minute, two alternatives have proven themselves: The relationship of several robots, or of several axis systems. In most cases, the products are shifted and turned in a layer-forming process according to the "Tetris principle". Lines are formed as close as possible and with a very tight clearance. Subsequently they are retained at the end of the conveying belt and the complete layer is gripped. The beverage industry in particular, uses layer-forming applications.
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Suction or mechanical gripping - weight, shape and surface of the article determine the safest principle of gripping.
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Layer-forming with a robot.
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In extreme cases every article differentiates from the other one
A particularly demanding is handling in distribution centers, where completely mixed pallets are commissioned. Instead of separating various parcels on pallets for hours, handling systems have to adapt themselves within seconds to the different formats. In extreme cases, every article differentiates from the other one. Flexible gripping systems combined with machine vision and sophisticated software solutions assure the best results for complex tasks.
Various gripping principles
The choice of the best gripping principle for such flexible solutions cannot be determined before the exact application and the targets are determined. With vacuum suction cups, the parcels can be gripped from the top and various layer patterns can be generated. Therefore suction cups, plates or bellows are widely used for handling of articles, which are packed in parcels, placed on intermediate layers, and can be used for articles with smooth surfaces as well. Depending on the weight and the surface of the article: type, quantity and storage of the suction cups and ejectors are selected. Unevenness or beveled surfaces can be balanced to some extent. In case of very thin intermediate layers of less than 0.5 mm, special vacuum systems have proven to work well.
Conventional vacuum suction cups have their limits, if porous or uneven articles or parcels with a special contour have to be handled. Even fast accelerations can reduce the process reliability of the suction cups considerably. In these cases, mechanical gripping solutions offer more advantages. At high speeds, the vacuum suction cups are superior since they easily absorb the occurring shearing forces. Products with porous surfaces or with clips which project at the top are better handled by mechanical grippers, since they grip the article laterally.
Modern mechanical gripping systems are equipped with very thin fingers made of chromium-plated metal sheet or from carbon fiber reinforced plastic materials. They allow minimum clearances of 3 to 10 millimeters, depending on the product’s weight. If these fingers are combined with a vacuum effect, the clearances can be further reduced, since the gripping force and the finger thickness can be reduced, too. Thin-film fingers are the remedy for flexible articles or sensitive products with smooth surfaces because they can grip laterally.
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The SCHUNK LEG packing gripper is a multi-purpose "quick-change artist"
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Mechatronic modules can be quickly adjusted
Over the past years, electrical drives have become very efficient and the sensors are getting smaller. Both make the handling systems flexible and versatile. Thus, new tasks can be quickly adjusted. Now the mechatronic components can be converted to intelligent subsystems, which can be easily scaled.
A gripper as much convertible as the tasks
The SCHUNK LEG servo-electric packaging gripper demonstrates how such a solution may look like. The expert for top-loading and palletizing tasks provide flexible and efficient concepts for packing and palletizing and can be easily integrated into existing plants. The modular system of the LEG can be equipped with various pneumatic or electric drives but can be also integrated as the seventh axis on a robot.
Due to its modular drive concept, it can be combined with all the common robot control units. In order to reduce cycle times, the gripper can pre-adjust its new position while the robot is about to approach its target position. Since robot and gripper are actuated via one single control unit or panel, new products or packaging units, and therefore changed gripping concepts and ways, can be stored in the robot software. This saves time and money at every change of assortment and product range and involves higher flexibility.
Conclusion:
For an optimum layout of packing processes it pays off to define the standards of the plant. Modern handling solutions offer a vast spectrum of variations and therefore also assure high cycle times. The plants become more process reliable and thus a good foundation for the future is set.
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2010-02
Flexible packing and palletizing
Adaptive handling systems provide dynamics and profitability if comprehensive ranges and frequent changes in assortment are given.
Every week a new product generation replaces the previous one. These products, which provide new impulses in trade, are a real challenge for the packing process. Faster, process reliable, and flexible automated solutions are in constant demand. They help to keep the handling costs under control, even at an increasing product variety.
 more...
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2010-01
How operators "play it safe" during turning operation
If a workpiece loosens from the chuck on a lathe, it can be dangerous to those working in the manufacturing hall. Because of this, the Employer’s Liability Insurance Associations, Standards and Safety Commitees, do everything in their power, to avoid accidents.
more...
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In Focus - 2010
In Focus - Archive 2009
In Focus - Archive 2008
In Focus - Archive 2007
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