Masking fixture and method

摘要

A fixture for selectively masking a turbine blade 60 includes a locator 10 with a separable receptacle 40 having portals 50. Guide bars 18 extend from the locator for guiding a pair of shield carriers 20 between deployed and retracted positions. Each shield carrier has a shield 26 projecting therefrom. In use, a turbine blade 60, whose root 70 includes a fir tree attachment 72 and a damper pocket 74, is mounted on the fixture so that the receptacle embraces the blade root. The shield carriers are translated along the guide bars until the shields penetrate through the portals and into the receptacle thus segregating the attachment 72 from the damper pocket 74. Masking powder 84 is then compressed into the receptacle to envelop the attachment while leaving the damper pocket unmasked. In one variant of the invention, the shields are independent, consumable shields 26a dimensioned and shaped to substantially conform to the size and shape of the damper pocket 74. The shields 26a are made of a thermally decomposable material and are wedged into the damper pockets 74 prior to blade masking. During the coating cycle, the shields 26a decompose at a temperature lower than the temperature at which coating vapors are produced to expose the damper pocket to the vapors. <IMAGE>