Dressing technology enables completely new possibilities in grinding with metal bonded CBN and diamond wheels. Article by Fritz Studer AG.
Alfred Mair, Head of Grinding Technology at Fischer AG, faces a challenge. The company, a manufacturer of high-precision spindles, has reached its limits in the grinding of exotic materials such as titanium and hard-to-machine hard materials under the increasing quality demands from the customers. That, plus their need to increase productivity, can’t be solved by conventional grinding machines.
Then came Fritz Studer AG’s S41 CNC universal cylindrical grinding machine. Specifically designed for large workpieces, it has a length between centres of 1000/1600 mm and a centre height of 225/275 mm. It processes workpieces with high precision up to a maximum weight of 250 kg, just as effectively as small and medium-sized workpieces. But the key for Fischer is the fully integrated WireDress dressing system.
“We had high hopes that we could use metal-bonded grinding wheels for a measurable and reproducible highest quality, have a higher productivity, more universal machining options as well as reduced tool costs,” Mair explains his expectations.
STUDER configured the S41 with WireDress based on additional requirements from Fischer. Thus, the machine received a special high-speed external grinding motor spindle, an innovative proprietary product of Fischer, in which the axial growth is particularly small.
In addition, the spindle is tapered at the rear end, avoiding possible collision situations. This is a specific benefit for face/shoulder grinding with the spindle at an angle. The S41 is supplemented with a fully automatic workpiece magazine and handling system, which ensures fully automatic series production of the high-quality precision components in a stand-alone operation.
“I am blown away,” says Mair. “Three to five times faster than with conventional technology, with absolute reproducibility, ground in a tolerance range of less than 1μm! I have never seen anything like that! I am extremely impressed.”
The Secret Behind
But how does this dressing technology work? Michael Klotz, project manager for development at Studer, explains, “It is a well-known fact that metal-bonded grinding wheels are much more durable and dimensionally stable when machining difficult-to-machine materials and ultimately enable higher productivity. The problem with this is that metal bonds can only be dressed to a very limited extent using conventional methods in the grinding machine. In addition to this, there is a high dressing tool wear associated with a low cutting ability. This is neither an operator-friendly, nor a high quality and process consistent dressing method.”
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