Glossary
What are transonic airfoils, and what is the active clearance control? Check out our technical dictionary and find out more about engine technology terms – from active clearance control to velocity triangle.
STEM drilling
STEM drilling (shaped-tube electrochemical machining) is a variant of electrochemical drilling, where material is removed by a hollow glass cathode after a voltage has been applied. Several of these glass tubes can be combined to form an electrode rake. This allows a complete row of holes (up to 30) to be drilled in one single operation. The process is used to produce cooling air holes in turbine blades and vanes. Its major advantage over other drilling methods, in particular laser drilling, is the high diameter/depth ratio which may be up to 1:70.
Print