Aerospace customers look to Premier for complete machining solutions

Premier Deep Hole Drilling is one of the UK's largest providers of specialist deep hole drilling, gun drilling and honing services. Although renowned for providing these services, the St-Albans-based company reports it now completely machines many more components, with around half of the current turnover generated by its machining centres and multi axis mill-turn machines. Civil and defence aerospace components account for 70 per cent of the company's business. Engine, nacelle and actuation system components are fully machined and supplied directly to the customers' assembly operations in the UK and across the globe. As well as current aircraft programmes, such as the Airbus A350XWB, A320neo and A400M, Premier also provides ongoing machining support for legacy products like the Rolls-Royce engine range. Managing director, Stuart Grant, says: "Produced from stainless steel, actuation work has ramped up, moving from development to flight approval and into production volume phases, to match the demand from the OEM. They are designed and produced to extremely tight tolerances, with the complex geometry at each end of the hollow component tied up tightly. "As such, they are not easy to produce. We have to remove so much metal out of the middle; they are long, thin walled and have tolerances of 0.1mm on length and 20 micron on concentricity between one end and the other. Wall thickness is minimised for weight saving. Some of the legacy components we produce have a wall thickness of 3mm or more. The new components have a wall thickness of between 1.6 and 1.8mm. It is a rare skill set required to produce these components consistently and on-time and we are very proud our customers trust us with such work." To support the increased demand for complete machined components the company purchased a second long bed Doosan Puma 3100XLY mill-turn machine with 2.1 m capacity between centres at MACH last year. "The mill-turn machine can hold the tolerance required and we specified it with a programmable steady to minimise the deflection of the part during machining and we have even managed to eliminate some grinding operations" explains Stuart Grant. Most of the actuation and engine mounting components are produced from 15-5 stainless steel, precipitation hardening stainless steels that contain chromium and nickel to provide an optimum combination of the properties of martensitic (gain high strength through heat treatment) and austenitic (corrosion resistance) grades. "Cutting speeds are critical as growth, shrinkage and distortion can all cause greater variance than tolerances allowed. We work closely with suppliers and customers during development of designs and production methods," Stuart Grant says. For the defence sector Premier is producing fuel delivery nozzles for the TP400-D6. A collaborative engine project for the A400M military transporter, partners include Rolls-Royce, MTU, Snecma and ITP. The fuel nozzle components are machined from 718 Inconel and S130, both of which are difficult to machine materials. As Stuart Grant says: "S130 is a chrome-nickel steel stabilised by the addition of niobium to overcome inter-granular corrosion common to other stainless grades after exposure to temperatures over 430 degrees C. While age-hardened Inconel 718 has to be machined using an aggressive, but slow cut with a hard tool, minimising the number of passes required. We have been doing the job for a number of years as the engine has progressed from design to testing, and it is now ramping up to production volume." The company's ongoing investment in its full machining capability is leading to increased demand as customers gain an understanding of what Premier can do. "Today, we produce fully machined spare nozzles for a range of Rolls-Royce high-bypass turbofan engines. Initially we provided a drilled blank, however our machining capacity and capability has grown so now we provide a finished component to the customer," Stuart Grant says. He concludes: "Most of our machining is carried out on components which include deep bores as carrying out all machining in house offers a cost saving solution. Most parts we produce for the aerospace industry are drilled and honed as the supply chain is subject to a tighter than standard finish. All our work is carried out to Aerospace AS9100 standards no matter what industry the work is for. For the future we will continue to invest in increasing our capability as demanded by our customers, while continuing to provide our core drilling and honing service many customers still require."