RPI, a specialist in high-accuracy rotary positioning and inspection devices, has developed a system for the measurement and assembly of gas turbine rotors that reduces the rate of teardowns by 95%.

The assembly of a gas turbine rotor is an extremely complicated and time-consuming process. It can take a week or more to assemble rotor, while close control of the assembly’s geometric tolerances is essential to ensure efficient performance and safe operation. If the rotor does not meet final criteria, it is subject to a ‘tear down’, where it must be completely disassembled and reassembled, costing tens or even hundreds of thousands of pounds in damaged parts, labour and delivery penalties.

These costly tear downs are avoidable if individual rotor component geometries are fully characterised and if the rotor assembly is simulated prior to its actual assembly. ‘Rotor stacking’ is the name given to this virtual assembly process.

RPI’s Integrated Measurement and Assembly Platform (iMAP) is a complete rotor-stacking solution featuring a high-precision, motorised air-bearing rotary table, an AccuScan circular geometry inspection system and IntelliStack rotor stacking software. iMAP systems can handle components as large as 35 tonnes and over 20 m3 with sub-micron accuracies, and a measuring resolution of less than 250 nm.

Some OEMs still use traditional dial indicator measurement methods, where data is manually collected and recorded from perhaps eight to 12 data points per part surface – one surface at a time. It sometimes takes a full shift just to measure a single part. iMAP replaces this time-consuming and error-prone process through the automated collection of up to 4000 data points per surface from as many as eight surfaces in one 30-second rotation of the part, resulting in tremendous savings in annual labour costs.

For further information
www.rpiuk.com