Abstract: A method of making a titanium fan disc for a gas turbine engine comprises the steps of providing a pair of identical forged titanium cylinders each having a central bore and a flat end surface at right angles to its central axis, preparing the flat end surface of each cylinder to a high degree of smoothness, abutting the prepared surfaces of the cylinders one against the other in axial alignment, removing air from between said surfaces, and diffusion bonding the cylinders end-to-end by hot isostatic pressing to form the disc.

Abstract: A delicate or awkward to grip component which is to be friction bonded to another has formed on it a flange or like formation which can be gripped firmly by a wedging action. The component is loaded into a shuttle, provided with a releasable wedge clamp, which is carried by the output drive member of a friction bonding machine. Machine forces for the necessary friction heating and bonding phases of the operation are transmitted to component through faces on the shuttle which abut the component flange.

Abstract: Known methods of controlling inertia welding and friction welding processes fail to control metal upset, and so require post machining of the welded components. The invention pre-determines the ideal rates of relative rotation, force applied and metal upset rates for a given material to be welded, enters those rates in a microprocessor memory and then connects the microprocessor to the apparatus on which the weld is to be effected. The microprocessor monitors the actual rates, compares them with the ideal rates and, should differences occur, generates signals from those differences with which to adjust operation of the apparatus.