The OP-20 is part of a suite of fixtures that bespoke work-holding solution specialist Brown & Holmes has provided for use in the manufacture of aircraft turbine blades. In this case, the Singapore-based client had a good idea of what required machining at different operations. The challenge for the Brown & Holmes team was to ensure repeatable and accurate work holding as the company was dealing with highly complex geometry.

The project involved machining the aerofoil on both sides and around the leading and trailing edges. Platform machining additionally takes place on the fixture and, as this feature is in long-term service, it also involves machining the tip of the blade off in the same process. Access is key to ensuring a good tool path and producing the part in a single, uninterrupted operation.

As a two-part fixture, the dovetail holds the root of the aerofoil in the bottom half, where the accuracy of hold is key. The tip of the blade is then held at the top, so even if there are only microns of inaccuracy, there will be millimetres out at the top of the blade. The two halves must be completely in line to ensure that there is no variation or thickness of the finished machine parts.

Brown & Holmes has been supporting this fixturing solution for over 10 years, with some 19 fixtures used in the client’s operation in Singapore. The company supports this process with cutting trials in the UK, tool manufacture in Italy and delivery to the end user in Singapore.

More information www.brownandholmes.co.uk