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In Focus - Archivo Octubre 2008
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ard on the outside, clever on the inside
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The high-performer SINO-R from SCHUNK provides increased productivity for HPC applications.
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01.10.2008 -
A lot of chips in a short time: if you want improved costs, quality and times when it comes to high-performance cutting, you would do well to use toolholders that are sturdy and can do more than just the basics ...
In high-performance cutting (HPC), toolholders have to stand their ground whilst simultaneously putting up with quite a lot. Although pure powerhouses can achieve the necessary chip volumes, they often affect the tool's cutting edges, the spindles and the workpiece surfaces. Users do significantly better with robust precision toolholders that also provide a generous dose of intelligence with their strength. In addition to perfect run-out, other vital requirements are strong rigidity and vibration dampening that is as pronounced as possible. This makes it possible to achieve large chipping rates and brilliant surfaces with minimal tool wear.
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The main goal is maximum productivity
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Compared to standard machining procedures, workpieces in high-performance cutting are machined at higher speeds, with larger loads and at a higher feed rate. The aim is to achieve a large chipping rate. Compared to straightforward high-speed cutting (HSC) – that is, machining at a high cutting rate – HPC generally involves lower cutting speeds and significantly larger cut depths. In addition to the machining process itself, HPC generally also integrates all the other factors involved in production. The objective is to ensure maximum productivity and performance reliability.
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Rigidity and vibration dampening are important
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The rigid version of SINO transfers torques of up to 850 Nm with ideal vibration dampening.
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The high feed rates raise the machining forces in HPC, which increases the load on machines and tools. The entire system, consisting of the headstock, spindle, toolholder, tool and workpiece, is like a chain that is only as strong as its weakest link. It is therefore vital to aim for as much rigidity as possible throughout the system. To avoid damaging vibration during machining, components with a low mass are used and bending arm lengths are kept to a minimum. With rigid, light and true running tools, it is also possible to use conventional machining centers with HPC. Blade materials specially designed for the procedure withstand the enormous alternating load on the blade; these are designed of carbide, cermet or cubic boron nitride, with coatings and are, in part, reinforced with fibers for break resistance.
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Major differences between precision toolholders
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SINO achieves large chipping rates – with perfect surfaces and maximum blade preservation.
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In addition to the tool's suitability, the function and technological workings of the toolholder are decisive to the success of HPC applications. If dismantling from the front side, large radial forces occur that can lead to the toolholder and tool system moving. The moving characteristics are governed by the toolholder's design, by the toolholder and tool system's projecting length and by the machining parameters. Furthermore, the axial pull-out forces attempt to pull the tool out of the toolholder. The greater the angle of twist on the tool blade, the larger the axial force.
Trials have shown that different individual precision toolholder systems lead to substantial differences in HPC. Toolholder systems developed especially for HPC that have strong rigidity as well as good vibration dampening provide clear benefits for HPC. These characteristics can be achieved in different ways.
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SINO: high-end elastomer clamps and dampens at the same time
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Perfect vibration dampening, large clamping force and simple tool change. SINO has a lot going for it.
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The attractively priced SINO-R universal toolholder from SCHUNK uses a high-end elastomer as its pressure medium. The exceptionally effective vibration dampening in this system provides an even cutting action and improved surface quality. This significantly reduces micro-blowouts on the cutting edge of the tools, which are often expensive. This reduces strain on the entire system, from the spindle to the machine table. Due to the long tool lives, SINO-R is a highly effective cost minimizer, noticeably reducing day-to-day tool costs. Added to this, SINO-R toolholders can be clamped quickly, simply and securely using a roller clamp or spanner wrench and there is no need for expensive peripheral devices. This lowers set-up costs compared to other clamping systems. SINO-R holds the tool in position even with the largest radial forces. For example, SINO-R can confidently transmit torque of up to 850 Nm with a diameter of 32 mm. Intermediate sleeves cover clamping ranges of 3 to 32 mm.
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TRIBOS-R: stable copper-alloy framework structure and dampener
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In the exceptionally radially rigid TRIBOS-R, inserts in the hollow chambers provide excellent vibration dampening.
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The TRIBOS-R precision toolholder from SCHUNK is specifically designed for the challenges posed by powerful machining. The toolholders in this series provide a substantially reinforced base body for receiving the high radial forces that occur in rough machining. The chuck is based on a framework-like chamber design. Compared to a solid design, the framework design has a significantly greater load torque with the same weight. Cast inserts made of copper alloy are set in the base body. The end face is therefore highly resistant to the impact of chips. The copper alloy inserts also provide excellent vibration dampening, which is approximately four times greater than that of heat shrink toolholders. This leads to significantly quieter machining, better surface quality and longer tool lives.
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The advantages of TRIBOS-R when it comes to vibration dampening have also been clearly shown in independent trials. Comparative investigations in the HSC-TOOLHOLDER II working group carried out by the Society for Production Engineering and Development (GFE e.V.) in Schmalkalden, resulted in the following statement: "When it comes to resonance frequency, TRIBOS-R chucks represent the upper limit. In other words, they have the smallest tendency to judder or vibrate."
TRIBOS-R enables controlled production and powerful tool clamping. As a result, larger loads and greater machining volumes can be achieved – which represents a major cost benefit. The rigid base body combined with a true running < 0.003 mm and an absolutely rotationally symmetrical design provide the ideal prerequisites for HPC. Add to this minimal balancing effort, wear-resistant clamping and simple handling. Furthermore, length adjustment in the clamping device is considerably simpler than with heat shrinking technology. TRIBOS-R is available for clamping ranges of 3 to 32 mm and is suitable for up to 55000 1/min.
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TENDO-ES: hydraulically clamped powerhouse swallows vibration
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Extremely short – extremely powerful – extremely cost-effective. TENDO-ES has powerful holding forces and frees up space in the machine room.
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The TENDO-ES hydraulic expansion holder from SCHUNK is new on the market. It clamps tools directly in the mounting shank. As such, the tool shank is supported by the spindle. With an L1 dimension of 26.0 mm, TENDO-ES is extremely short. The result is maximum holding forces for transmitting large torques and a lot of additional space in the machine room.
The innovative TENDO-ES precision toolholder has an impressive run-out of < 0.003 mm and excellent vibration dampening. The tool can be changed in seconds using a hexagon socket screw. Users benefit from brilliant surfaces, maximum dimensional accuracy and long tool lives. Furthermore, using intermediate sleeves guarantees full flexibility.
TENDO-ES is available for the SK 40 and BT 40 interfaces, the clamping diameter is 20 mm, or 3 to 20 mm with intermediate sleeves.
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Summary:
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High-performance cutting contains considerable potential for productivity improvements. The procedure will become more and more important in the future. Even with conventional machines, significant increases to the chipping rates can be achieved without major expense. Specialized tools and toolholders enable users to ensure that increased performance does not compromise quality, service life or the machine. A lot can be achieved even with comparably little investment.
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12.2008
Quick jaw change brings flexibility and substantial savings
Flexibility in production is a crucial competitive advantage. Only companies that can respond to demand with flexible yet absolutely precise production can supply their customers rapidly with a constantly increasing variety of products without needing to build up expensive and inefficient stocks.
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11.2008
Pneumatics or mechatronics? … It all depends!
To date, pneumatically driven gripper modules have been used primarily in gripper technology. Recently, however, more and more electric grippers have been coming onto the market. Both competing systems have powerful arguments in their favor.
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10.2008
High-Performance-Cutting (HPC)
Hard on the outside, clever on the inside: Toolholder systems developed especially for HPC that have strong rigidity as well as good vibration dampening provide clear benefits for HPC.
más…
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09.2008
Cleanroom
The importance and the use of cleanrooms in assembly and handling are constantly increasing.
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08.2008
Clamping Force / Torque
We are frequently confronted with torques on a daily basis, even though we do not recognize them as such.
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07.2008
Convenient robot or attractively priced spindle gripper?
A significant potential for increasing efficiency in modern machining processes is the automated loading and unloading of the machines.
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06.2008
Polygon clamping technology - round pegs in polygonal holes
The principle behind polygon clamping is surprisingly simple. The know-how that makes it work is however highly advanced.
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05.2008
Packaging
A package for everything
Packaging is a universal function that is required in practically every industry and meanwhile is so important that it has become a separate industry itself.
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04.2008
Magnetic clamping technology has strong attraction
Workpiece clamping with electroermanent magnets reduces set-up times by up to 50 percent and brings about significant advantages especially in the manufacture of large parts.
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03.2008
Quick-change systems speed up production
Changing systems for components such as grippers and tools add a high degree of flexibility to production processes
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02.2008
Vibration damping
Improves surface quality and reduces wear on the tool and spindle.
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In Focus - 2013
In Focus - Archivo 2012
In Focus - Archivo 2011
In Focus - Archivo 2010
In Focus - Archivo 2009
In Focus - Archivo 2008
In Focus - Archivo 2007
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