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The first of two turnkey Viper grinding technology export orders for producing nozzle guide vanes that were won by Hardinge has been accepted and is ready for shipment to the customer in China.

While the Chinese contract comprises a standalone, manually operated Bridgeport FGC-2 Flexible Grinding Center, the second order currently in build is for a fully integrated robotised cell around a similar machine, due to be installed in India later this year.

Both projects were based on the five-axis Bridgeport FGC-2 Flexible Grinding Center, which has the rigid construction of a vertical machining centre to capitalise on the good access for loading and unloading.

It can also combine milling and drilling processes within the same cycle as the grinding operation under Heidenhain’s iTNC 530 control.

The control incorporates software developed by Bridgeport for the Viper grinding process that includes twin fully programmable coolant nozzles for grinding and wheel cleaning.

The coolant is supplied by two high-pressure pumps within a totally paperless, environmentally friendly FSE coolant filtration system.

The Chinese contract for the manually loaded FGC-2 version required the machine to provide multi-face grinding of all the radial areas of the NGV.

By combining a formed cubic boron nitride (CBN) wheel in the 16 position automatic wheel-changing system, a special groove that was previously hard-turned as a separate operation was able to be included by Hardinge in the same cycle.

The FGC-2 will produce NGVs in a cycle time of less than 45 minutes.

Meanwhile, the fully automatic FGC-2 cell, due for delivery to India, will halve the processing time of NGVs compared with existing methods.

It will produce batches of engine sets and incorporates a Gudel gantry loader with Kuka robot and a Hexagon coordinate measuring machine (CMM).

The CMM initially establishes the ‘best fit’ of the throat area of the NGV raw casting to maximise air flow, from which the machining datum is created by grinding to achieve the flow.

Following the grinding cycle, which, in the Indian cell, involves the creation of three location faces, the CMM checks conformance and stores the data, and the part is automatically returned to the loading station.

Should any corrective grinding be required – for instance due to excessive casting stock levels – this would be carried out automatically within the cell.

Erowa fixturing is used to achieve the high-accuracy location in the grinding machine and CMM with relative data transferred between the CMM and the Heidenhain control via an onboard integrated data chip.

The FGC-2 cell will also produce three high-pressure and three low-pressure turbine-blade components that involve a total of 32 different operations over the six parts.

Also included within the automated grinding process is a small requirement for milling and drilling.

The Bridgport flexible grinding centres have been highly successful for the Leicester facility, with more than 80 installations around the world.

Applications have involved the grinding of aero-engine and land-based gas-turbine components, such as NGVs and blades.

Hardinge Machine Tools

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