Having served the Aerospace and Industrial Gas Turbine (IGT) markets for over 30 years, Winbro Group Technologies has intimate knowledge of the individual components used in the most demanding part of a turbine engine - the high pressure turbine blades, nozzle guide vanes, combustors and other similar components. This expertise is reflected in the array of high technology, non-conventional machining systems manufactured by Winbro and used to produce the cooling holes, seal slots and other features in these parts.
Winbro has always been at the forefront of machine and process development, employing a range of different technologies and processes such as high speed EDM drilling and milling, Laser drilling, Laser cutting and Laser ablation, together with ECM forming, STEM and Capillary drilling. Winbro’s outstanding success within the industry is due in part to the company’s foresight in understanding that the different processes are more often complimentary rather than competing, leading to the development of both single process machines and latterly single machines that use a combination of processes.
The concept of a “Combination Machine”, incorporating for example both High Speed Drilling EDM and Laser Ablation, provides the perfect solution to machining operations on today’s HP turbine blades and vanes. The complex and intricate patterns of cooling holes required on these parts are fundamental in satisfying the demands for reduced noise emissions and increased fuel efficiency on the latest generation engines, such as those used to power the Airbus A350 and Boeing’s 787 Dreamliner. As the turbine blades and vanes on these engines run at high temperatures that often exceed the melting point of their material, they not only require round and shaped cooling holes but the surface is further protected by a Thermal Barrier Coating (TBC) - typically ceramic. This non-conductive coating is not conducive to the EDM process, therefore alternative production methods of producing the cooling features need to be considered.
In many cases it is possible to drill through this ceramic coating and continue to generate the cooling hole using a high peak power pulsed Laser. This option however, can have an impact on hole quality in terms of the heat affected zone (HAZ), recast layer and micro-cracking, especially in the rotating turbine blades, which in turn could result in a failure to meet the stringent criteria laid down for components of this type.
The unique solution, pioneered by Winbro Group Technologies, is to first remove the Thermal Barrier Coating (TBC) and the adjoining bond coating at the hole location using laser ablation. This exposes the parent material allowing the hole to be drilled using the High Speed Drilling EDM process. Drilling the metering hole using Winbro’s acclaimed signature analysis eliminates the need for a back wall impingement stopping material, required when drilling by Laser. This dual process not only ensures hole quality but the minimum of TBC is removed, without risk of de-lamination of the TBC around the through hole.
Combining the two processes within a single machine brings additional benefits as there are no alignment issues when switching between the 2 different operations and the ablation Laser can also be used, not only to remove the TBC in a controlled manner, but also to machine a complete diffuser 2D or 3D shape.
Winbro Group Technologies also offers a combination of different laser types within a single machine, where for example, a high peak power Laser is used for drilling operations and a fibre Laser used for ablation. The requirement to both laser cut and laser drill large annular turbine components for a Russian customer, led to the development of yet another Winbro turnkey solution based upon 2 different laser sources. In this instance, a high peak power GSI 604D Laser was ideally suited to drilling the cooling holes at shallow angles to the surface, but this Laser has only limited capability for cutting. To achieve the high cutting rates and cut quality demanded by this application, a 3kW Trumpf TruDisk Laser system was also integrated within the same WGT Delta 5 axis machine. This combination provides the customer with a highly capable, no compromise solution to his drilling and cutting operations.
Component production benefits from unrivaled expertise
Winbro Group Technologies has always embraced the philosophy of providing a total solution to customer’s requirements. With an extensive portfolio of machines, an in-house tooling design and manufacturing facility and expertise gained from optimising the diverse machining processes, the next logical step for Winbro was to set up a component machining facility at its Coalville site. The WAM (Winbro Advanced Machining) facility allows Winbro to offer a range of non conventional machining services to their customers within the Aerospace and IGT markets.
This resource can be used in a number of different ways by Winbro customers. For companies that have placed an order for one of Winbro’s machining systems, WAM provides the opportunity to both define and refine the process and machining parameters on a machine of the same type and using exactly the same process. This capacity for parallel component manufacturing is invaluable where there is a need to produce production level parts ahead of the delivery of a new machine.
For manufacturers requiring an increase in capacity through a second source for strategic components, then WAM offers the option for short, medium or long term production offload as required. The WAM facility can also be utilised by companies that do not wish to invest in complex technology and gain the necessary industry accreditations. In addition, as Winbro actually manufacture the technology used in the WAM facility, increasing the capacity here is easily achievable as everything is under the control of Winbro Group Technologies at the Coalville site.
The machining processes available include a six axis high speed EDM drilling cell that has capacity for drilling holes and shaped diffusers in Aero and IGT blades, vanes, segments, combustors and other engine components. Unique to Winbro is the multi-electrode drilling and sensing systems that are integrated into the generator designs and which permit efficient drilling of multiple holes or multiple diffusers simultaneously, additionally EDM milling (HSM) is used to produce features such as seal slots
WAM has also developed highly innovative techniques for salvaging blades and vanes that have cooling holes blocked or restricted by coating processes. The technique may use multiple processes, as required by the type of coating on the individual component and the severity of the blockage or restriction. The yields from this recovery process are setting a new precedent in the industry and offer a cost effective and rapid route to component salvage.
The Winbro Advanced Machining facility also has considerable experience of using Laser ablation for the removal of coating overspray, as well as diffuser machining in coated and non-coated components. WAM’s laser ablation process offers exceptionally high quality metallurgy. Where aero or industrial gas turbine engine component repair is required, Winbro is able to offer one, or more of its Laser cladding, welding, ablation and inspection technologies.
This new facility is certified with ISO9001 and AS9100, accredited with Nadcap (non-conventional processes) and has also achieved independent customer accreditations with some of the industry’s major blue chip OEM’s. The addition of WAM means that Winbro Group Technologies has achieved its objective of offering a complete solution to their customers, ranging from component level production to full turnkey systems.
The innovation and technical know-how that has propelled the Winbro Group to its position as a global leader in cooling hole technology is now further enhanced by the additional invaluable experience gained from component production within WAM.