Austrian abrasives manufacturer, Tyrolit, who together with Rolls-Royce and Raysun engineers invented and then developed the well known Viper grinding process, will launch the new VIPER ULTRA range of grinding wheels, which greatly extend grinding performance on normally difficult to machine nickel alloys.
VIPER ULTRA wheels have a new, patented matrix and are made using a sintering process that closely controls wetting and coating of the grain surface, which in turn improves bonding of the grain. The highly porous bond system is capable of absorbing high dynamic loads without damaging the bond bridges, resulting in optimal use of the abrasive grain.
Benefits include better form holding and profile retention, which reduces the dressing frequency. Wheel life is therefore extended and there is less wear on the diamond roll dresser.
Lower grinding forces result in reduced stress on the component and workholding system. Power consumption is less and the lower heat input to the workpiece minimises the risk of burning. Cool cutting is particularly important when grinding nickel-based aerospace components, such as turbine blades, rotor blades and nozzle guide vanes, which are primary applications for VIPER grinding.
Two sets of comparative, non-CD grinding results on nickel aerospace components using VIPER ULTRA wheels and their predecessors show the dramatic productivity improvements that may be achieved.
A Makino iGrinder G5 was used to grind the dovetail form on a rotor blade in two operations. The machine was fitted with a VIPER ULTRA wheel, 220 mm diameter by 25 mm wide, running at 40 m/s. Table speed was 2 m/min and infeed was between 0.1 and 2.0 mm, depending on the operation. A 30 per cent increase in the number of components ground per wheel from 200 to 260 was achieved as well as a 35 per cent increase in productivity. The result was an annual cost saving of Euro 42,000, based on 35,000 blades per year.
In a second application, the fir tree root form of a turbine blade was ground on a Bridgeport FGC 2 in four operations using a 250 mm diameter by 25 mm wide VIPER ULTRA wheel running at 40 m/s. Table speed was 1.5 m/min and infeed varied from 0.1 to 1.5 mm. Production per wheel jumped from 150 to 250 parts per wheel - a 67 per cent increase - and productivity was 30 per cent higher. An annual cost saving of Euro 20,000 was achieved, based on 20,000 components per year.
A number of products recently introduced to the UK will also feature on the Tyrolit stand, as follows.
During high performance, external cylindrical grinding processes, there is a build up of heat in the grinding area. Increasing forces due to wear constantly weaken the grain and bond structure. With high stock removal volumes, the boundary layer between these component parts of the wheel is heavily eroded.
Tyrolit's CSS ULTRA improves grinding performance by restructuring the micro architecture of the grinding wheel. It has been achieved using high quality materials along with an innovative sintering technology, enabling the abrasive grain to withstand much greater loads when in use, without breaking away prematurely. The automotive and bearing industries are particular target markets.
The new specification of the POLARIS product line allied to the use of new CBN grains promote maximum tool life, traverse speeds and stock removal. Controlling layer properties during the electroplating process using a strong, laminar nickel matrix allow the CBN layer of the grinding wheel to achieve previously unattainable adhesion strength for high performance, external cylindrical grinding, especially in the automotive industry.
In developing GENIS, Tyrolit has introduced a new bond system that makes it possible to guarantee optimal wetting of the CBN grain, even with very low levels of bond content. Through careful choice of composition of the bond components, crystallisation is specifically controlled under selected firing conditions. This makes it possible to achieve porous structures with high mechanical strength that exhibit maximum resistance to the effects of cooling lubricants.
The cool grinding specification of the high-performance tools reduces grinding forces and makes efficient use of the CBN grain. Lower grinding forces, minimum tool wear and maximum profile retention are confirmed in practice, opening up a wide range of application possibilities, again with the automotive sector very much in mind.
For low cost, high productivity manufacture and resharpening of solid carbide and high speed steel drilling and milling tools and saw blades, a new generation of diamond impregnated grinding wheels has been introduced by Tyrolit. Called STARTEC-HP, they combine an improved bond, new abrasive types and a new core.
The easy-cutting bond system results in outstanding cooling characteristics during creep feed grinding of flutes. The products are easy to dress, which is particularly important for profile wheels. A non- ferrous core system is used which is lighter and provides better vibration damping characteristics than a steel core; and it is more tolerant to operator error, eliminating sparking if the wheel approaches the component too quickly.
The wheels are said to allow an increase in traverse speed of about 50 per cent and reduce flute grinding time by a massive 40 per cent. Further benefits are typically 20 per cent lower power consumption, accurate profile holding and 30 per cent longer wheel life.
The development of high strength bond systems is important to meet the demands of today's creep feed market, particularly in the aerospace sector. The bond matrix needs a high level of adhesion to the abrasive grain to withstand the extreme dynamic loads encountered during an optimised grinding process. The goal is to hold the abrasive grain in the bond matrix for as long as possible.
This requirement has been successfully met with the development of the new STRATO ULTRA wheels. The result is higher metal removal rate and significantly improved profile retention, while avoiding grinding burns.
For gear grinding, Tyrolit offers MIRA grinding wheels with a patented bonding system and special, sintered aluminum oxide abrasive grains. The combination results in superior profile stability, a reduction in stress on the workpiece and decreased grinding times.
Based on the type of grinding machine and module of the workpiece in the range 0.5 to 8.0, Tyrolit has developed a full programme of 1- to 7-start grinding wheels. They are delivered un-profiled or pre-profiled, with or without an additional undercut for wheel clearance, based on module, pressure angle and number of starts.
On behalf of: Tyrolit Limited, Eldon Close, Crick, Northants, NN6 7UD
Tel: 01788 824500. Fax: 01788 823089
Web site: www.tyrolit.com
Contact: John E Willis, Managing Director
Issued by: THE RIGHT IMAGE Ltd,
PO Box 42, Twickenham, TW1 1BQ.
Tel: 020 8891 0603.
Contact: Chris Wright.