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In Focus - Archive May 2007
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While other operators have to retrofit the machines in a complicated way, the quick-change pallet system UNILOCK from SCHUNK significantly reduces cycle times in production.
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01.05.2007 -
On the quick-change pallet systems, work-pieces, devices, and clamping equipment can be positioned, fixed, and clamped quickly and with precision in a single operation. These systems drastically shorten set-up times and are therefore an important factor if production cost saving is of concern. Particularly during the production of small series and a broad variety of work-pieces, quick-change pallet systems help considerably to save costs, sometimes up to 90 percent. SCHUNK GmbH & Co. KG, headquartered in Lauffen, Germany, has been offering sophisticated SCHUNK UNILOCK quick-change pallet systems for the past ten years and continues to develop these systems. Due to the uniform interface and the manifold versions being offered, SCHUNK UNILOCK is in the forefront of quick-change pallet systems.
The pressure on process costs reduction in the metal and plastic industries is continuously growing. Companies who maintain consistent quality with reduced set-up costs and minimal manufacturing times are achieving advantages in this highly competitive market. There is much to be gained from implementing new technology with regard to process improvements. Numerous companies still do not use a quick-change pallet system, even though it offers enormous advantages and significant cost saving potential.
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While suppliers of tooling machines launch time-saving concepts to the market and machines are currently designed for high-speed metal cutting, the operator sometimes still sets up the machine table with old technology. Particularly for small series and a broad variety of work-pieces, but also for automated production processes, the selection of the right clamping equipment and work-holding system is becoming increasingly important. For manufacturers in the metal cutting industry, this means it is profitable to critically analyze the primary process times and the non-productive times.
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Savings potential of up to 90 percent
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Those who want to achieve optimum improvements in productivity also need, aside from the corresponding machines, fast clamping systems that can be retrofitted. SCHUNK, of Lauffen, Germany, being one of the most innovative and experienced manufacturers of workholding systems, offers a series of pneumatic and hydraulically actuated clamping systems. The bestseller is the UNILOCK quick-change pallet system from SCHUNK, which has held a leading role in workpiece clamping for the last ten years. With this system, workpieces and clamping devices can be fixed, located, and clamped within seconds. Since the workpieces are simultaneously set up outside of the machine during the primary process time, the idle times are reduced considerably. Examples of application for metal cutting companies prove that, by using this system, set-up costs are lowered by up to 90 percent.
Moreover, the use of a quick-change pallet system considerably increases flexibility. Without having to reset the zero point of the machine, the operator may interrupt the machining program at any time, remove the workpiece or clamping device, and use the system on another machine. The operator can measure the workpiece or clamping device on a measuring machine or, after having finished an urgent job, set it up again on the original machine within a short period of time.
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Module NSE 138T
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The basis of the quick-change pallet system is the pneumatic clamping modules, which can be integrated into the machine table or mounted onto the device plates. Once these modules are aligned and fixed, the machine’s point-of-reference is set. The modules can clamp workpiece-carrying pallets, clamping devices, or workpieces with one or several clamping pins. The actual clamping is done by a clamping pin, which is set directly in the workpiece or clamping device. This clamping pin is moved in and locked via the radial adjusted clamping slide in the quick-change pallet system. Fixing or positioning of the SCHUNK system is done via a short taper.
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This ensures a repeat accuracy of less than < 0.0002” (0.005 mm). Locking is done mechanically via a laminated spring, is self-locking, and clamps form-fit. UNILOCK generates retention forces of up to 16,860 lbs (75,000 N) per clamping pin. In contrast to other quick-change pallet systems, the spring-loaded UNILOCK from SCHUNK does not have to be connected to compressed air while the workpieces are machined. Compressed air is only used to release the UNILOCK modules. The workpieces even remain clamped in case of a sudden drop in pressure. A pressure of 6 bar is enough to unlock the clamping modules. This is the same pressure as with every compressed air system.
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Extremely fast changeover for every machine
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Clamping slides
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With a total of ten types of modules, pull-down forces between 1,125 lbs and 5,620 lbs (5,000 N and 75,000 N) are achieved. SCHUNK offers a suitable solution and ensures high flexibility for every application. However, it is the uniform interface which makes the SCHUNK UNILOCK a real "set-up time killer": The use of a single method clamping system ensures that the workpiece can be "quickly and accurately moved," so to say, from one machine to the other, from module to module, and from machining to machining. This is a deciding factor, especially when planning a flexible, facility-wide clamping solution.
The clamping slides ensure fixation of the safe hold of the clamping pin. The locking system is self-locking and locks form-fit.
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Benchmark in automated manufacturing
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The robot removes workpieces that are set up preliminarily on pallets from a rack system. The uniform clamping pins of the SCHUNK UNILOCK allow the workpieces to be machined on other machines at a later time, without retrofitting.
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While considering enormous advantages and the increasing cost reduction pressure, the quick-change pallet system from SCHUNK will continue to expand into automated processes and offer reliability in the precise clamping of workpieces and devices by using robots and handling equipment. A requirement for this level of automation is having machine control units which are connected to the monitoring and control functions of the clamping modules.
Automated machining centers equipped with SCHUNK UNILOCK allow the workpieces to be taken out of a rack system with a robot, loaded precisely in the machine area, and placed in the rack again after machining. While the robot carrying the clamping pallet swivels into the working area, the command for pneumatic unlocking of the module is given via the machine control unit.
The conic centering of the clamping pins ensures that the workpiece may also be loaded and unloaded diagonally. A second control pulse of the machine then ensures that the compressed air is turned off and that the module is locked via spring force. By means of automated machining centers, complete shift operations can be carried out without personnel. This increases flexibility and efficiency and lowers costs considerably.
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Tombstones and clamping cubes for simultaneous machining of five sides
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SCHUNK UNILOCK tombstones ensure high flexibility.
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The module NSE 138-T is special and has been particularly designed for tombstones. Due to the low height of 0.433” (11 mm), it can be directly attached to the plane face of the tombstone and connected with screws. Advantage: The tombstone is made of steel, cast iron, or aluminum and does not require an extreme wall thickness of the tower. Even standardized and cost-efficient tombstones can be used without problems. Tombstones or clamping cubes allow several workpieces which require the same set-up to be machined simultaneously. Thereby, the tombstones can be unlocked individually or in groups. This is important when clamping several workpieces. If the tombstones should be equipped with a zero point clamping pin again, the complete tower can be retrofitted outside of the machine, while the workpieces are machined on another tower. Finally, the complete towers will be quickly exchanged, positioned, and fixed by using the quick-change pallet system. Alternatively, the workpieces can be preliminarily set up on pallets and then fixed in a tombstone.
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Low costs and short reaction times
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The clamping cube with 20 quick-change pallet modules creates maximum flexibility at low set-up costs. Such a system amortizes even within a short period of time.
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If you want to be successful in metal cutting, you will have to reduce manufacturing cost and, at the same time, you must be able to react quickly. SCHUNK UNILOCK contributes two things: The quick-change pallet system is straightforward, precise, and allows fast retrofitting of the clamping devices and workpieces, therefore it saves time and money. Customers with broad business activities, and small production series increasingly recognize the advantages of a uniform and integrated zero point clamping solution. Even large workpieces, such as landing airbrakes of large airliners, can be fixed quickly and precisely with SCHUNK UNILOCK.
Conclusion:
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Set-up times can be considerably reduced by using UNILOCK from SCHUNK. |
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The machine idle times are lowered. |
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The uniform interface for all machining applications eliminates expensive retrofit-ting of the workpieces and makes for ease in re-assigning jobs to other machines. |
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Precise clamping ensure the highest machining quality. |
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The investment amortizes within a short period of time. |
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12.2007
Balance quality
Round is better
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11.2007
Patented and very impressive: the SCHUNK multi-tooth guide
Distribution of the load on many shoulders – that is the principle of multi-tooth guidance, developed and patented by SCHUNK
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10.2007
Micro-handling
Handling in miniature -
a gripper that fits in a matchbox
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09.2007
Run-out Accuracy of Toolholders
Micron’s best friend – with precision for precision
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08.2007
Service Robotics
A Sensitive Touch for Sensitive Tasks – Robots in Service Gain Independence
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07.2007
Tool Clamping
A tiny difference can have a big impact
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06.2007
Hygienic Design
High-tech creations for culinary delights
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05.2007
Reduction of set-up costs with the quick-change pallet systems
Savings potential of up to 90 percent
more...
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04.2007
Minimum quantity lubrication - MQS
- For minimum costs and maximum protection of the environment
A possible solution in searching for the optimum lubrication system
more...
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In Focus - 2013
In Focus - Archive 2012
In Focus - Archive 2011
In Focus - Archive 2010
In Focus - Archive 2009
In Focus - Archive 2008
In Focus - Archive 2007
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