Product category:
Abrasive grinding wheels, abrasives
News Release from: Saint-Gobain Abrasives | Subject: Vortex abrasive grinding wheels
Edited by the Manufacturingtalk Editorial
Team on 27 June 2005
Highly porous wheels abrasive grind
efficiently
The ability of highly porous wheels to abrasive-grind 'difficult' materials efficiently well produces impressive savings in gear manufacture, automotive, and turbine work.
It is not often that a major step forward in grinding wheel manufacture is announced, but Saint-Gobain claims a world first with its Vortex Technology wheels, production of which for all of Europe is carried out at the company's factory in Stafford Tests on 383 wheels in a large range of sizes showed a process capability index of Cpk 1.83 for elastic modulus, very close to the holy grail of 6 Sigma
This article was originally published on Manufacturingtalk on 19 Nov 2002 at 8.00am (UK)
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Low wheel-to-wheel deviation in elastic modulus is an indication of the consistency of wheel composition and the precision of the firing cycle.
Every Vortex wheel is also tested for density before despatch.
The result, over the same 383 sample, showed a very respectable Cpk of 1.33.
Further reading
High porosity grinding ups output, avoids burning
Highly porous, permeable grinding wheel, used to creep-feed grind a groove in a steering wheel part increased parts/wheel by 150% and reduced production cost/part by 27%.
Turbine parts ground precisely, no burning
Subcontractor is using open-grained, aluminium oxide wheels in 'Viper' grinding - maintaining a sharp, accurate profile in Inconel 939 with minimal heat generation.
PTFE compound improves performance of valves
A glossy black non-abrasive specialty PTFE compound makes softer mating surfaces and has high resistance to deformation and a low coefficient of friction.
An added benefit from this consistency is less variation in wheel balance, resulting in almost minimal need for correction prior to and during operation.
The end result is extreme repeatability of grinding performance from batch to batch.
Launched last year with a single, 60 grit size and initially aimed at creep feed applications on heat-sensitive materials in the aerospace industry, the Vortex range has now been expanded with the introduction of 46 grit for heavy stock removal on larger parts and 80 grit for achieving finer finishes and tighter form tolerances, such as on fir tree root forms.
The range of wheel sizes available in the Vortex product has also been greatly expanded and now extends down to 220mm diameter for use on machining centres using the Rolls-Royce-developed 'Viper' (very impressive performance extreme removal) production process.
For other applications such as surface, gear, roll and cylindrical angle-approach grinding, diameters go up to 1020mm and widths to 406mm.
Vortex wheels are especially suitable where the contact area is large and/or the material being ground is sensitive to heat.
The highly porous structure with its widely spaced, aluminium oxide, abrasive grains allows coolant to flow efficiently into the cutting zone.
This eliminates loading of the cutting surface, minimising the risk of burning and metallurgical damage to the component, even under aggressive metal removal conditions.
Due to the free-cutting characteristic of Vortex, 20% less power is used for a given metal removal rate, reducing the amount of energy in the form of heat transmitted to the component, minimising any tendency of the part to move within a fixture during machining, reducing residual stress in the material and saving energy.
These benefits translate into higher all-round grinding efficiency and accuracy.
The ability of the wheels to machine 'difficult' materials efficiently well suits them to gear manufacture and automotive applications as well as to aerospace and land turbine work.
* Wheel consistency results from natural porosity - Saint-Gobain Abrasives invested three years of R and D in developing a process to manufacture highly porous products which, unlike all other porous wheels on the market, are completely natural and need no organic additives such as naphthalene to create artificial pores.
This had never been done before and is still unique and patented.
Reducing the number of constituents allows the production process to be controlled much more precisely, resulting in the excellent Cpk values achieved.
Moreover, burning out of organic compounds is avoided, making Vortex wheel manufacture more environmentally friendly.
* Production performance figures - in one production example at a customer site, a low pressure, Inconel turbine blade for an aircraft engine was Viper ground on a Makino horizontal machining centre in a 38% shorter contact time than previously, creating extra production capacity.
40% fewer wheels were used for grinding the batch of blades and production cost per part was down 22%.
Additionally, quality was improved owing to better surface finish, less component deflection during machining, and absence of metallurgical damage.
In another example, a stage-1 gas turbine stator vane with an 8mm deep by 10mm wide slot was ground with a 500mm diameter Vortex wheel on a Blohm Profimat.
The result was a more than threefold increase in the Inconel parts produced, up from 17 to 54, before the wheel needed replacing.
Contact time was halved from 7.28 to 3.64 minutes.
Most importantly, the competitor's wheel caused extensive burning of the alloy, leading to time-consuming testing after machining to ensure metallurgical integrity.
There was no burning with the Vortex wheel and post-grinding inspection has been eliminated.
At another customer, a nickel alloy heat shield for a land turbine showed a doubling of wheel life with Vortex from 13 to 26 parts, using a 240mm diameter by 60mm wide wheel on a Maegerle grinder.
Cycle time was not an issue owing to the overall TAKT time for the process, but in any case the contact time was down by 18%.
Other Maegerle users making industrial turbine blades have enjoyed much larger contact time reductions of 50, 49 and 41% respectively and savings in wheels consumed of 45, 28 and 38%.
Best contact time reduction of all is reported by a manufacturer of nickel-based, high temperature aircraft turbine housings, which is using a Vortex wheel on a Danobat grinder to achieve a 60% improvement.
Wheels used per part is down 48% and production cost has been halved.
In the automotive industry, a steel steering component has a 6mm groove ground with a 400mm diameter wheel.
Vortex increased parts per wheel by 150% and reduced production cost per part by 27%.
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