On one hand however profiling a grinding worm needs time and on the other it alters the geometry of the tool Depending on the choice of grinding process it has to be repeated in very short intervals in order to guarantee production at the same level of quality This is where Liebherr comes in offering a CBN tool with an implemented modification and demonstrating on an example workpiece that better economic production is possible with these tools.
CBN stands for cubic boron nitride Next to diamond it is the second hardest cutting material in the world It consists of a 3D matrix made of boron and nitrogen atoms that can develop a broader spectrum of crystal forms than diamond It has high thermal conductivity and a low coefficient of friction The workpiece heats up much less than grinding with corundum for example It is possible to machine very hard materials reliably with CBN Also CBN grinding worms can be smaller which means that the range of applications is greater than with corundum.
CBN tools are currently experiencing a comeback They may be expensive to procure but make gains with unit costs on modifications Liebherr Verzahntechnik GmbH Kempten Germany has been using galvanically coated CBN since 1988 It is a highly durable grinding material A significant increase in the grinding performance of modern corundum has been achieved in recent years but compared with CBN it comes with the disadvantage of the amount of effort required for dressing which is encountered most prominently on topological grinding processes.
With these processes the number of workpieces per dressing cycle is significantly reduced due to the limited shift possibility which in turn raises tool costs and also cycle times It may be possible on corundum tools e g for distortion free generating grinding to increase the workpiece number for each dressing interval through new mathematical solutions but this also applies in the same way to the use of CBN tools.
With CBN dressing times can be dispensed with completely which means that cycle times and manufacturing costs can be reduced CBN is highly machinable and generates an extremely low measuring complexity A CBN grinding worm is clamped in and the grinding process begins straightawaymdashwith no need to make corrections beforehand.
The unit costs of a test workpiece m 1 53 mm z 81 mm included a special width modification with corundum at euro4 25 with a cycle time of 114 6 seconds while the same grinding process with CBN was euro3 38 cheaper and considerably faster with a cycle time of 78 seconds.
Where the number of producible workpieces per dressing cycle with corundum is in the two figure range it can occasionally reach well into the four figure range with a CBN coating.
Each situation needs to be assessed individually to determine which grinding worm is the most viable Liebherr advises its customers on whether CBN is the better alternative for their numbers and application scenarios.
In a dressing free CBN process all parameters are predefined and ldquofrozen rdquo This is a crucial difference between corundum and CBN processes All corundum processes are subject to changes through dressing which can impair grinding worm quality This might be wear of the dressing tool.
Micro ceramic dies have to be ground by micro diamond wheels and accuracy of truing View Development of Cross and Parallel Mode Grinding Machine for High Na Aspherical Mold and Die.
Jan 30 2020nbsp018332CBN generating grinding is an economic alternative to grinding with corundum On one hand however profiling a grinding worm needs time and on the other it alters the geometry of the tool Depending on the choice of grinding process it has to be repeated in very short intervals in order to guarantee production at the same level of quality.
Micro grinding ppt vivekanandvidyapeethin CRYOGRNIC GRINDING authorSTREAM micro grinding ppt 18 Dec 2008 CRYOGRNIC GRINDING authorSTREAM Presentation procedure to download ppt pls tell me I need in conventional grinding process High heat generation Introduction of tensile residual stress and micro cracks occurThe effects of three.
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