February 13, 2020: HAIMER at GrindTec 2020: hall 2, booth 2113 - Fine balancing increases productivity during the grinding process
During GrindTec 2020, the international Trade Fair of grinding technology in Augsburg (hall 2, booth 2113), HAIMER, the European market leader for clamping and balancing technology, will present the most recent developments in the area of highly precise grinding wheel adapters, balancing and presetting technology, as well as accessories. The primary focus is on the Tool Dynamic balancing machine series, which uses a simple method to determine and eliminate the unbalance of grinding wheels and other rotating tools. The user profits from higher concentricity, reduced vibrations and increased productivity overall.
“There is no mystery about unbalance,” says Andreas Haimer. As the managing director of HAIMER GmbH, the world market leader in balancing technology for tools, grinding wheels and holders, he is intensively involved in milling and grinding tools and their optimal use. He explains: “Unbalance in a rotating tool system is caused by an uneven distribution of weight. Centrifugal forces are generated during rotation and these increase quadratically with the speed of rotation. This means that – with the same degree of unbalance – the spindle with a rotational speed of 10,000 rpm generates 25 times the centrifugal force as with a rotational speed of 2,000 rpm.”
So much for theory. In practice, the unbalance on grinding wheels and tools can stem from a number of different reasons. The tolerance of the grinding wheel bore, the homogeneity (mass distribution of the wheel), as well as parallelism and concentricity of the grinding wheel play an important role. The tolerance of the grinding wheel arbor, as well as the dressing and profiling process also have a direct effect on the unbalance and thus on the dynamic concentricity of the grinding wheel during the machining process. This causes vibrations, which are also transferred to the machine and the blank. It negatively impacts the entire machining process and the grinding results in terms of the surface quality and dimensional accuracy of the workpiece. In the case of tool grinding, this results in large chipping on the ground tools to varying degrees. Unbalance has a similar effect on cutting tools and their workpieces to be machined.
Unbalance has a negative impact on lifetime of tools and spindles
Moreover, unbalance causes increased wear on the grinding wheel or tool and headstock. Studies and experience have shown that the lifetime of the spindle can be reduced by up to 50 percent. Andreas Haimer points out that many machine and spindle manufacturers now require their customers to only use balanced tools: “Otherwise they won’t provide a guarantee or only a limited one for the spindle.”
However, many users continue to prefer reducing the rotational speed, feed rate and cutting depth to minimize the vibrations caused by unbalance and thus achieve the necessary process reliability and the required quality of the workpiece. Although this does lead to quieter machining and improved surfaces, it also results in lower metal removal rates and, therefore, lower productivity.
The much better solution would be to eliminate the unbalance in tool systems from the very beginning. According to Andreas Haimer, what seems complicated at first glance “can be done very easily and is affordable for everyone. Tool holders, grinding wheels and large rotors up to a diameter of 1,000 mm can be balanced using our modular balancing system Tool Dynamic. Our machines achieve optimal repeatability of < 0.5 gmm, which corresponds to an eccentricity of 0.5 µm for a 1 kg tool.”
Practice shows: balancing is simple and effective
“We can achieve 25 to 30 percent higher feed rates with balanced grinding wheel sets. The tool life and dressing cycles of the wheels have been extended to the same extent” – is what many users in the tool grinding sector have been heard to say. They also confirm the improved quality of high-performance HSS and solid carbide tools that have been produced. The effects of balancing are especially positive when it comes to grinding solid carbide tools. This is because the material is very brittle and should not be subjected to impacts that could cause hairline cracks and result in tool breakage.
The improvement in quality is not only attributed to the elimination of serious damage such as this. Thanks to the better quality of surfaces and cutting edges, the tools achieve longer tool lives for the customers and, in some cases, allow the machining of more challenging materials and small diameters.
Optimized concentricity with Tool Dynamic
HAIMER introduced the first Tool Dynamic machine to the market in 1996. A complete series has been developed since then and offers the right solution for every requirement. Designed as a tabletop and add-on machine, the Tool Dynamic TD 1002 is, for example, an ideal solution for balancing grinding wheels. The balancing adapters with an automatic clamping system center the tool with µm precision like the tool grinding machine, thus ensuring the highest measuring and repeat accuracy. The radial and axial runout of grinding wheels can even be measured in a single setup with the optional concentricity measuring device. The TD 1002 is operated via an integrated keypad and display.
The Tool Dynamic Comfort and Comfort Plus models, which are most frequently used in practice, are operated by touch screen via the modern and user-friendly TD 4.0 balancing software. It provides the option of balancing in two planes in a simple way.
The Tool Dynamic series includes numerous expansion stages up to the universal CNC-controlled balancing machine TD Automatic, which automatically performs the correction for the unbalance directly in one or two planes. The latest development is the Tool Dynamic Preset Microset, which perfectly combines balancing and presetting technology. The tool is clamped by a high-precision balancing spindle with the well-known and patented HAIMER adapter system.
The edges of the grinding wheels can be optimally measured on this machine with the aid of an edge finder.
This machine is now also available in an Industry 4.0 version. Here, the determined, maximum permitted speed of the grinding wheel package is automatically transferred directly to the control system of the grinding machine. This means that the machine can then be operated productively without exceeding the permitted maximum speed.
HAIMER offers special accessories to make the balancing process as cost-effective, simple and fast as possible. This includes a complete range of grinding wheel holders for tool grinding machines of all common machine tool builders: including Vollmer, Walter, ISOG, UWS Reinecker and Rollomatic. But HAIMER now also offers a range of suitable holders for the currently very popular multitasking machines, in which grinding technology has been integrated in addition to milling and turning.
Balancing – a well-rounded performance, also economically
A simple calculation enables HAIMER to prove how worthwhile it is to balance tool systems: A modern tool grinding machine costs around 100 euros per hour (single shift operation, 1,600 hours running time per year). Increasing the grinding performance just 10 percent by balancing allows you save up to 10 euros per hour. This adds up to 16,000 euros per year and machining center. Experience from Haimer’s own production and reports from customers who have been balancing their grinding wheels for a long time, have shown even higher increases in productivity through balancing. On top of this come savings as the result of improved surface quality, higher dimensional accuracy and less machine downtime.
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Duo-Lock™ blanks for self-grinding
HAIMER will not only present the latest balancing technology at the GrindTec 2020; tool grinders will be able to see even more interesting innovations at booth 2113 in hall 2. HAIMER will present high-quality carbide blanks with the Duo-Lock™ thread, which can be further processed to special tools. The Duo-Lock™ system developed by HAIMER is the most stable interface for carbide tool heads. With modular milling tools, it achieves a similarly high cutting performance as the latest generation of solid carbide endmills. The innovative thread design of the Duo-Lock™ system and its patented double cone surface combined with a third contact area provide maximum stability, load capacity and a high runout accuracy of 5 µm. Moreover, HAIMER has extended its Duo-Lock™ program: The range now includes collets with Duo-Lock™ threads, which are ideal for conventional ER collet chucks for milling, as well as for driven tools and rotary indexing machines.