Product category:
Abrasive grinding wheels, abrasives
News Release from: Tyrolit | Subject: Polaris and Genis superabrasive wheels
Edited by the Manufacturingtalk Editorial
Team on 14 November 2007
OD wheels grind hard/'exotic'/tough
alloys
Two ranges of external cylindrical grinding wheels have been introduced for large volume production of components from difficult materials such as hardened steel and tough exotic alloys.
Tyrolit has introduced two ranges of external cylindrical grinding wheels for machining large volume production of components from difficult materials such as hardened steel and tough exotic alloys One is Polaris, which uses cubic boron nitride (CBN) grains in an electroplated nickel matrix
This article was originally published on Manufacturingtalk on 16 Nov 2005 at 8.00am (UK)
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The other is Genis, which uses CBN grains in a vitrified bond.
i Tyrolit claims that its superabrasive wheels offer increases of up to 60% in wheel life when compared with competitive CBN wheels.
The wheels are intended mainly for the automotive sector, although applications are to be found in the aerospace, motorsport, medical and bearing industries as well.
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Tyrolit told manufacturingtalk.com that more aggressive grinding, and therefore shorter cycle times, are achieved with CBN when compared with aluminium oxide wheels.
The results are as follows.
* Higher productivity and lower cost per part.
* Fewer wheel changes.
* Lower infeed force and energy consumption.
* Reduced machine wear.
Contributing further to economical manufacture of components is less frequent truing and dressing of the vitreous bond CBN wheels, while the single-layer electroplated types do not need to be dressed at all.
Tighter dimensional tolerance, better surface finish and improved metallurgical integrity of the manufactured components leads to improved repeatability of the grinding process.
* High grinding ratios - sharpness, thermal stability and high fracture strength of Tyrolit's CBN crystals allow the high grinding ratios achievable with Polaris electroplated and Genis vitrified wheels.
For each application, Tyrolit offers the following service.
* Analyses and optimises the process, providing a turnkey package including a customised wheel for the application and the machine on which the components will be ground.
* Advice on wheel preparation, grinding parameters and coolant delivery.
The strong, laminar structure of the nickel layer securing the CBN grain in POLARIS wheels, together with the grain's free-cutting topography, allow previously unattainable adhesion strength to be achieved for external grinding.
Wheels up to 700mm in diameter and 450mm wide can be supplied to a maximum wheel weight of 150kg.
Run-out, concentricity, parallelism and right angularity are all accurate to within 5 micron.
* Camshaft grinding - in an application involving roughing the cam profile and bearing journals of a cast iron camshaft on a Schaudt CF41, a 404 mm diameter wheel using a new grain quality and embedding depth, was used at 120m/s, increased tool life from 85,000 to 130,000 parts.
* Hardened gear shaft - grinding turned grooves on a hardened steel (58 - 62 HRc) gear shaft using an Emag-Karstens machine.
A 450mm diameter wheel with a profile optimally adapted to the wear behaviour during grinding and the required finish of the radii resulted in a 45% increase in tool life.
In its development of Genis wheels, Tyrolit focussed on the needs of vehicle engine and gearbox producers with a view to increasing grinding efficiency and eliminating production bottlenecks.
Tyrolit produced a new, vitrified bond that optimises wetting of the CBN grain, even at low levels of bond content.
Through careful choice of bond constituents and firing cycles, crystallisation is closely controlled to achieve porous bond structures for good chip clearance, high mechanical strength and maximum resistance to the effects of lubricants.
The resulting free-cutting, low-force grinding at high rotational speeds makes efficient use of the CBN grain, extending tool life and retaining the wheel profile for longer, said Tyrolit to manufacturingtalk.com.
It also impacts favourably on the metallurgical properties and finish of the component surface.
* Cam shafts - in a comparative test for a cam shaft manufacturer, a Genis wheel lasted 60% longer than the incumbent CBN wheel when finishing the 52 HRc cam profiles at 100m/s on a Schaudt Zeus grinder.
Moreover, internal stresses in the component were significantly lower and the power drawn by the grinding spindle was reduced.
* Crankshaft - a 40% extension of wheel life was achieved in the grinding the main and pin bearings on a crankshaft.
A 700mm diameter Genis wheel on a Junker Jucrank machine ground the 54 - 58 HRc features at 100m/s.
Despite the large amount of stock removal, the free-cutting CBN wheel chosen for the job increased the number of shafts ground per wheel from 4,200 to 5,900, with good process reliability.
As is standard with all Tyrolit's industrial grinding tools, Polaris and Genis wheels are fitted with a Wheel Memory, an embedded microchip that holds data on the grinding wheel.
Information stored includes wheel specification, setting dimensions for key datums, maximum operating speed, the length of time it has been used and remaining life.
* RFID - radio frequency identification enables two-way wireless transfer of this data between the wheel and the machine tool's CNC.
Set-up time is reduced, with immediate restoration of process reliability after tool change, and crash avoidance is guaranteed as each wheel has a unique indentification.
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