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In Focus - Archive March 2011
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Micro cutting extreme
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01.03.2011 -
Clamping tools used for micro cutting have their own rules. The subtle tools, the high spindle speeds, and the extreme precision requirements are a challenge for every tool manufacturer and user. Those who want to achieve continuously precise results, need mountings with a high run-out accuracy and balancing grade. Moreover, they should be as slim as possible and resistant to dirt. Furthermore, they have to assure that even small tools can be precisely adjusted and exchanged.
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TRIBOS is widely spread in the clock/ watch industry. The delicate parts require the highest degree of accuracy.
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The high-precision metal cutting has its source in the clock and watch industry, which always has enormous requirements. During machining of movement platines, extremely low tolerances in diameter, and position have to be observed. Tolerances of 0.004 mm are not uncommon here. In the course of time, other industries also discovered the possibility of using micro cutting. The range of users is spread from dental- and medical technology, over the optical industry, to the mold making. Today, the tolerances for micro forms partly amount to just +/- 0.003 mm, the edge sharpness to 0.01 mm.
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TRIBOS polygonal toolholders from SCHUNK achieve optimum results in micro cutting.
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Due to the polygonal clamping technology, even special materials such as e.max can be machined in the dental technology with grinding pencils.
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Clamping systems used in the micro range encounter their limits
Such values can be only achieved by using toolholders, which assure a continuously perfect true-running accuracy. Conventional collet mountings will not cope with it. Their true-running accuracy varies so extremely from clamping operation to clamping operation, that they are not acceptable for process-reliable micro cutting. Moreover, collet chucks have to be cleaned regularly and are laborious in handling.
Even in case of precision toolholders it is well worth to have a closer look at them. For achieving exact results, the true-running- and repeat accuracy should be better than 0.003 mm, measured at an overhang length, which is 2.5 times higher than the shank diameter. Due to the high speeds and a balancing grade of G 2.5 at 25.000 rpm this makes sense. When choosing a clamping system, it is worth checking whether these values can be continuously maintained. Some systems cause material stress due to friction or generation of heat during the clamping operation, and the mountings lose their high precision in a creeping manner, and tolerances cannot be maintained any more.
A similar problem is pollution. If smallest chips penetrate into the mounting and stick, the balancing grade can be negatively influenced. With every clamping operation the toolholder loses precision, since the chips inside the mounting cause wear. In case of multi-part toolholders, such as precision collet chucks, this effect arrives even sooner. Scrupulous cleaning during the tool change and regular intensive cleaning is the only protection.
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In the medical technology electrodes for clamp coagulator apparatus are machined with TRIBOS.
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The bars of filigree graphite electrodes partly measure less than 0.1 mm. Here TRIBOS also demonstrates its skills.
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Other clamping technologies are clearly superior
If on compares the relevant clamping systems, the polygonal clamping technology, a patented technology of SCHUNK, the competence leader for clamping technology and gripping systems scores very well. While coolants evaporate during heat shrinking, and residues remain in the clamping diameter, these tools are also high-priced, energy-intensive, and sometimes an exhaust air system has to be installed, as well. Polygonal clamping technology does not burden the budget, does not pollute the environment, or endanger the health of the operator. For the clamping operation, no electric current is necessary. Moreover, the smaller shank diameters of the heat shrinking mountings are quickly overloaded. Due to the thermal influences, and the various thermal expansion coefficients of toolholder and tool, the expensive micro tools can jam in the mounting.
Heat shrinking toolholders often lose their run-out accuracy if they are repeatedly heated and cooled down in a short period of time. In contrast to this, the polygonal clamping technology reliably maintains a high true-running accuracy for thousands of clamping cycles. During the clamping operation, the polygonal toolholder radially deforms. Therefore no expansion in length takes place, and it is assured that the tool can be adjusted with a minimum tolerance in length of 0.01 millimeters. This is also a major advantage towards heat shrinking toolholders, where during the cool down phases the pre-adjusted length can reduce. This effect is also called setting behavior.
Even towards collet chuck mountings, the polygonal clamping technology can score. Due to the clamping principle, no moveable components are needed for this system. This makes the precision toolholder much more insensitive in view of the mechanics, and continuously assures a maintenance- and wear-free clamping. Compared with the multi-part toolholders, the cleaning effort is considerably lower. In order to exclude pollution from outside, the slots at the front of the mountings can be vulcanized on request.
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In the mold making industry finest structures are achieved by TRIBOS-RM.
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Polygon-shaped mounting bore
Formore than ten years, the patented polygonal clamping technology has established a good reputation under the designation TRIBOS, and works according to an asthonishingly simple clamping principle. Instead of round mounting bores, the toolholding system is equipped with polygonal shaped ones. If a clamping device is actuated from the outside with a defined pressure, the mounting bore deforms within the permanently elastic area to a cylinder. This process ranges below the Rp 0.2 % limit so that dangerous grain changes within the steel can be excluded. In this condition, the tool can be easily inserted into the toolholder. Then the outside pressure is reduced, the inner diameter moves into its original polygonal shape again due to its material elasticity, and due to the residual stress of the steel, the tool is force-fit clamped. This also applies for smallest tool diameters of 0.3 mm. With a permanent run-out and repeat accuracy of less than 0.003 mm at an overhang length of 2.5 x D, and a balancing grade G 2.5 at 25.000 rpm, the TRIBOS toolholder meets highest requirements. According to users of the high-precision metal cutting industry, TRIBOS is the first toolholder to achieve precise results when milling cutters with a cutting diameter of 30 µm are used.
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TRIBOS Principle
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TRIBOS-Mini is an expert for micro cutting. It clamps tools as of a tool shank diameter of 0.3 mm.
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Two high speed versions and a universally suitable extension are available
SCHUNK offers three toolholder versions with polygonal clamping technology for metal cutting purposes. The TRIBOS-RM is an extremely compact toolholder with a high radial rigidity. The standardized interfaces HSK-E 25, 32, 40, ISO 10 and HSK-A 40 are perfectly suitable for small, highly dynamic machining centers. TRIBOS-RM was tested for speeds of up to 80.000 rpm, and even clamps small tool shank diameters between 3 and 12 mm. Its clamping force provides highest cutting performances at excellent run-out accuracies and thus increases productivity. Due to the framework design, TRIBOS-RM damps vibrations and assures long tool service lives. Its high-precision run-out accuracy assures a particularly uniform cutting action and excellent surface qualities. This particularly pays off if brilliant surfaces already have to be achieved during the milling operation, for example, if medical components cannot be polished.
The second version is the TRIBOS-Mini. This toolholder particularly has made a name for itself in the medical technology and electrical engineering, the jewelry, watch and clock industry, as well as the fine mechanics and mold making industry. All tool shanks with h6-tolerance can be clamped as of a diameter of 0.3 m. It is particularly suited for delicate works, where it can show its ability: during engraving, as well as machining of housings, shapes and electrodes. The mounting is designed for speeds of up to 205.000 rpm. In many cases the use of highly priced special tools is not necessary and they can be replaced by TRIBOS-Mini. And this provides enormous cost advantages to the users. Due to the clamping principle, the micro mounting is markedly slim. Therefore it is possible to plunge deep and highly precise into the workpiece.
The toolholder extension TRIBOS-SVL Mini also profits from this advantage. It is slim, long and therefore specialized for working within limited spaces. It is an all-rounder and disposes of a run-out accuracy of less than 0.003 mm. The benefit: The extension can be combined with various toolholders, and even for limited spaces, precise and economic solutions can be offered.
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Ingenious: The handy SVP-Mini and RM clamping devices are ideal for micro cutting.
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The SVP-Mini allows process-reliable tool change in no time at all.
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Ingenious clamping device for fast and secure tool change
For the TRIBOS-RM, TRIBOS-Mini, and TRIBOS-SVL Mini SCHUNK has developed two handy clamping devices, which simplifies the tool change. At both devices the required pressure is already fixed. The operator inserts the toolholder into the clamping device, turns the clamping screw with an Allen key to the bottom stop, and changes the tool. Within 20 seconds, the complete process is finished. The innovative clamping unit saves time, energy and lowers set-up costs. Moreover, operating errors can be excluded.
Optionally the clamping devices can be operated in the hand or directly at the machine spindle. Alternatively it can be vertically or horizontally fastened at the workbench. Due to the permanently integrated clamping bushings, reduction inserts are not required, and thus the tool change is furthermore simplified and costs are saved. Compared with the previous TRIBOS-SVP clamping device, in which all the TRIBOS mountings can be universally clamped, are handy units with a firmly defined clamping pressure, and are more attractive in price. They are particularly attractive for beginners, who want to keep their initial investment costs as low as possible. A reduction of the initial investment costs by more than 75 % is possible with them.
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Information box:
Beside the standard interfaces, the SCHUNK TRIBOS polygonal clamping technology is also available for a whole series of small, highly dynamic machining centers. Alfred Jäger GmbH for example, offers mountings with interfaces WK 16 and 19 for the Jäger high frequency spindles. For Röders or Makino machining centers, the TRIBOS toolholder is offered in a completely sealed version with taper geometry. In order to avoid the ingress of chips or grinding dust into the spindle, the slots of the mountings are vulcanized at the front and the coolant opening is resinified at the backside. But TRIBOS is also worldwide successfully used on other HSC machining centers of other manufacturers.
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12.2011
Clamping solutions for automated mass production
Efficient manufacturing means automated manufacturing. This particularly applies if large series are machined. This is when the clamping vises, which are the direct interface to the workpiece, playing an important role. In only a few seconds, they have to mount the components, safely and precisely align them, clamp them with-out deformation, and after machining they have to be reliably released. In view of the several million clamping cycles, which have to be carried out by many clamping vises being exposed to chips and coolant, process reliability is one of the decisive factors of success.
 more...
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11.2011
Modularity the factor of success
When designing gripping systems for handling and assembly applications, standardized modular systems will play an increasingly important role in the future. They reduce the necessary time for project planning and commissioning, and lower the investment costs. Due to the standardization, they offer optimum preconditions for stable processes. Since modular designed units can be flexibly modified and enlarged, they can be re-configurated for any changes that come up in the future.
more...
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10.2011
Producing more efficient
For a number of years, everybody was talking about the energy efficiency issue. Increasing energy costs, a growing environmental awareness, and the political guidance were all triggers for many companies to highlight the energy consumption of machines and components in their communication with the public. Efficiency is much more than simple energy efficiency now, especially when considering the
time- and cost aspects in regards to efficiency. When all these factors have been considered in a holistic way, the full potentials for modern machining and production become visible. The modern clamping devices and gripping systems make it clear how complex the possibilities are.
more...
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09.2011
Welding demanding materials crack- and pore-free
Laser welding technology is second-to-none, regardless of whether you are dealing with gears and injection molds or delicate and challenging welding works. When conventional cw lasers and many Nd:YAG-lasers reach their limits, modern process strategies can help to machine demanding welding metallurgies, different types of materials, or micro components process reliably and efficiently. Laser welding is particularly used if components have to be joined at a high welding speed, because slim welding seams, and a low thermal distortion are required. Compared with other welding techniques, the energy during laser welding fully penetrates into the material.
more...
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08.2011
More than a "Stopgap":
Intermediate sleeves ensure safe clamping and precision
They appear to be unimposing - but they are located at a decisive interface in the chain of the metal cutting process. Between toolholder and workpiece, the intermediate sleeves influence reliability and precision of the clamping operation. The thin-walled, mostly slotted precision sleeves cover the difference between the clamping diameter of the toolholder, and the workpiece which has to be clamped. Functioning like reduction inserts, they multiply the fields of application of the toolholders or arbors, compensate tolerances, and ensure safe and gentle clamping of gear wheels. The newest sleeve design can do even more. Intermediate sleeves with nozzle effect extend the tool service life and increase the volume machining.
more...
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07.2011
Changing, machining, compensating -
current trends in robot accessories
In dealing with industrial robot efficiency cycle rate and process reliabilty largely depend on their front ends, the grippers and other tools, but also from the effectors’ interfaces to the robot arm. Robot accessories have a great influence on the robot’s performance, flexibility and fields of application. Latest developments of quick-change systems, driven tools, compensation units, and power sensors show that the potentials of modern accessory components are enormous. Experts assume that their importance for handling, assembly and manufacturing will continuously increase.
more...
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06.2011
Deformation-free clamping:
From the plastic chuck jaw to the hybrid chuck
In case of rings, housings and other workpieces which are highly deformable dur-ing processing, conventional 3-jaw chucks quickly reach their limits. If the clamping forces are too low, there is no secure hold. If they are increased, workpieces de-form, and precision is reduced. A comparison shows the alternatives, the differ-ence between them, and how users can achieve an optimum result.
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05.2011
Service robotics is the future key market
Insiders are convinced that golden times lie ahead for service robotics. Around the world companies and institutes have recognized the potential of robots as helpers for humans, and are working on everyday solutions. All different kinds of businesses are interested in service robotics, from large companies, to innovative startups, and also conventional manufacturers of industrial robots, electronic and automation components.
more...
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04.2011
Having set-up times under control
You cannot earn money with a turned off machine. However, in many companies the workpieces are still set-up in a complicated and time-consuming way on a grooved table while the plant is turned off. But solutions exist, which optimize the machine tool load. Modern quick-change pallet systems demonstrably accelerate the machining process, and at the same time, ramp up the precision and process reliability score. This leads to a reduction of set-up costs of up to 90%.
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03.2011
Toolholders for micro cutting
Clamping tools used for micro cutting have their own rules. The subtle tools, the high spindle speeds, and the extreme precision requirements are a challenge for every tool manufacturer and user. Those who want to achieve continuously precise results, need mountings with a high run-out accuracy and balancing grade. Moreover, they should be as slim as possible and resistant to dirt. Furthermore, they have to assure that even small tools can be precisely adjusted and exchanged.
more...
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02.2011
Leight-weight design increases efficiency of Gripping Systems
Light-weight modules are now playing an increasing role in the area of gripping systems. Integrated into the system, they are saving energy at the same efficiency, or achieve a considerably higher efficiency at the indentical energy consumption. In both cases, the efficiency of the whole system is increasing. This is why the lightweights are so interesting for plant manufacturers, system integrators, and users. Since light-weight solutions had the reputation of being overly expensive in the past, recent developments now show that efficiency and cost control can go hand-in-hand. Modern designs, materials and techniques are paving the way to lighter solutions, which are rigid and robust, too. This also offer many more advantages.
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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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