Method and compression apparatus for introducing residual compression into a component having a regular or an irregular shaped surface

A method of inducing compression along a surface of a predefined area of a workpiece comprising the steps of:

• placing a workpiece in position for processing;
• determining surface irregularity along the predefined area by calculating a range of variation of surface topography using a population of workpieces;
• using a control system to direct a compression apparatus having a tool head in the form of an impact tool and wherein the control system operates to control the tool head so that the tool head operates with a predefined force of impact, reciprocating rate and spacing of impacts against the surface of the of the predefined area and wherein the tool head follows a predefined virtual control surface positioned within the workpiece below the actual surface of the predefined area by an amount that is greater than any surface irregularity along the surface of the predefined area so that any surface irregularity along the surface of the predefined area is processed with the predefined force of impact;
• and
• using the tool head to strike the surface of the workpiece and create a specific controlled zone of plastic deformation achieving a prescribed depth and magnitude of residual compression along and within the surface of the workpiece.