Abstract: The method is suitable for the micromachining of accurately aligned holes in the aerofoil surface of a component such as a jet engine turbine blade or vane which comprises a ground anchorage portion and a cast aerofoil portion. The method uses a micromachining apparatus which is pre-programmed to machine holes in the aerofoil surface when that surface is in a predefined reference position and orientation in the apparatus. Initially the component is mounted in the micromachining apparatus by means of its anchorage portion. At least one probe is then moved into contact with the surface of the cast aerofoil portion to derive the positions of selected points on that aerofoil portion. From the derived position data, angular and linear offset data may be calculated to define the deviation of that cast aerofoil portion from the reference position and orientation defined in the computer memory of the micromachining apparatus.

Abstract: The method is suitable for the micromachining of accurately aligned holes in the aerofoil surface of a component such as a jet engine turbine blade or vane which comprises a ground anchorage portion and a cast aerofoil portion. The method uses a micromachining apparatus which is pre-programmed to machine holes in the aerofoil surface when that surface is in a predefined reference position and orientation in the apparatus. Initially the component is mounted in the micromachining apparatus by means of its anchorage portion. At least one probe is then moved into contact with the surface of the cast aerofoil portion to derive the positions of selected points on that aerofoil portion. From the derived position data, angular and linear offset data may be calculated to define the deviation of that cast aerofoil portion from the reference position and orientation defined in the computer memory of the micromachining apparatus.

Abstract: The invention provides an apparatus and method for detecting an out-of-line electrode prior to the start of an electrical discharge machining (EDM) process. The invention involves positioning an electrically conductive test component in an accurately defined location relative to a workpiece. The test component has a test hole of a size and shape corresponding to the hole to be drilled in the workpiece by an electrode of an EDM machine. The electrode is then inserted into the test hole. If the electrode is correctly aligned then it will not contact the test component and no electrically conductive path will be formed between the electrode and the test component. If such contact is detected then the electrode is misaligned and the EDM process is stopped. This sequence is repeated immediately before the commencement of drilling of each hole in the workpiece.

Abstract: The invention provides a method of drilling holes sequentially through a workpiece using a laser gun with a camera positioned axially in-line with the drilling beam of the laser gun. Each image from the camera is analysed by digital image processing techniques to control the positioning of the laser nozzle relative to the workpiece and/or to compensate for errors produced in previously drilled holes. By feedback from the digitally processed images it is possible to repeat the auto-focusing of the laser automatically throughout the drilling of a large number of holes in the same workpiece, to adjust the drilling of subsequent holes in order to bring the hole characteristics closed to a predefined optimum, or to abort work on a particular workpiece if hole diameters exceed a given tolerance range.