Development of an efficient 5 axis CNC machining process for the production of complex Inconel duct fittings used in aero engine de-icing duct assemblies.

SL Engineering won a contract to produce Inconel de-icing ducts used on the Boeing 787 Dreamliner aircraft. One of the major challenges of this project was to produce a series of complex 5 axis machined duct fittings from a nickel-chromium-based superalloy material that required specialist cutting tools and multi-load work holding techniques and tooling, to enable the efficient production of these complex prismatic fittings.

The original idea was to produce the parts in a five-operation machining process involving multiple turning, roughing and milling operations on five separate machines. The early machining trials resulted in long cycle times and work holding/clamping issues, utilising methods and tooling that were transferred from the previous supplier.

Therefore, to produce the parts efficiently and accurately SL re-engineered the parts using a full prismatic 5 axis machining approach which allowed machining of the parts in only two operations versus five. This 5 axis approach employing a multi load fixturing solution produced much more accurate and repeatable results from the reduced set ups, and achieved much quicker cycle times.

The time taken out of the process and the improved product conformity led to a robust and repeatable process, which led to over 95% OTD on these running production parts, zero defects (100% RFT) and allowed SL to deliver a cost down leading to the award of a 5-year contract with our globally based OEM customer.