Putting precision on the map

Putting precision on the map

RPI’s iMAP is a high accuracy circular geometry inspection and assembly system specifically designed to measure and assemble turbine rotors

Aerospace Manufacturing hears how a new high accuracy circular geometry inspection and assembly system from Rotary Precision Instruments is enabling aero engine manufacturers and overhaul shops to capitalise on predicted growth by achieving higher levels of quality whilst also saving time, money and resources.

Big changes are underway for the global aerospace market. The number of airline fleets with new technology engines is increasing and there is massive re-fleeting in North America. By 2025 new engine and overhaul markets are forecast to grow to $1 trillion and $46.8 billion respectively, and as these figures suggest, there are clearly big business opportunities for aero engine manufacturers.

But there are also a number of challenges. As ever, fuel efficiency comes top of the list, closely followed by the demand for lightweight engines, not to mention environmental regulations requiring reductions in both noise and carbon emissions.

In addition, airline operators don’t want overhaul costs to increase, meaning manufacturers need to find a way to make money whilst ensuring prices are kept on a level playing field.

So, what can manufacturers do to ensure they are equipped to meet the increased demand for both new engines and overhauls? According to Bath-based Rotary Precision Instruments (RPI) – a specialist developer and manufacturer of precision positioning devices for high accuracy rotary and angular inspection systems since the 1940s – aero engine manufacturers need to change the way they traditionally measure and assemble turbine rotors.

Rotation innovation

The solution? RPI’s iMAP – an ultra-high accuracy circular geometry inspection and assembly system. Specifically designed to measure and assemble turbine rotors, iMAP has been independently verified and proven by industry experts to offer manufacturers significant operational improvements over their traditional measurement methods.

Indeed, RPI has already successfully supplied ten iMAPs including one to a major aero engine manufacturer based in Shanghai and two to a major aero engine manufacturer in Singapore, saving the manufacturers time, money and resources by significantly reducing inspection times and the need for costly teardowns due to inefficient rotor assembly optimisation.

But, according to Jim Palmer, RPI’s sales manager, a large percentage of aero engine manufacturers still use traditional methods such as spinning a table manually in order to measure turbine rotors but this throws up a number of problems.

Firstly, its time consuming. Secondly, only eight data points can be measured. And thirdly, because data is written down manually, it is open to human error.

“Let’s face it,” says Palmer, “no matter how skilled and diligent the engineer, the chances are that at some point the wrong figures will be written down therefore compromising the quality of the assembly and increasing the chances of expensive rotor tear downs.”

So just what is it that makes RPI’s iMAP better? For starters, iMAP has been specifically designed to inspect large and heavy components such as aerospace engines and gas turbine rotor components combining a high precision rotary axis, rigid column unit, anti-vibration granite base and AccuScan multi-channel circular geometry inspection software. iMAP is fully compatible with any shop floor environment whilst maintaining world class accuracies more commonly seen in the standards laboratory.

Jim Palmer, sales manager of Rotary Precision Instruments

AccuScan – iMAP’s computer based data acquisition software –  enables aero engine manufacturers to improve quality by quickly measuring up to 3,600 data points on up to eight surfaces simultaneously per revolution which reduces inspection times by 90% and improves gauge repeatability and reproducibility by up to ten times compared with more traditional methods.

AccuScan can also distribute inspection templates and data files easily via email for analysis using the free downloadable viewer or via PDF generated reports and CSV files. So, if an engine was built in the UK and then repaired and overhauled in Singapore, the engineer in Singapore could look at the original inspection data when engine was made and instantly see what’s changed, which in turn keeps airline operators happy by cutting down the time and therefore cost spent on overhauls.

And last, but by no means least, is IntelliStack – IMAPs Rotor Stacking Program and ‘holy grail’ according to Palmer.  iMAP’s significantly improved inspection data derived from AccuScan is used by IntelliStack to solve the mathematical problem of how to best assemble a multi-stage rotor assembly to achieve minimum runout or unbalance of the finished rotor.

“IntelliStack is the holy grail of iMAP,” states Palmer, “as it tells aero engineers how to assemble turbine rotors most effectively. The better the rotor is built, the better it will perform making for a more fuel efficient, less noisy engine which is great in terms of meeting environmental regulations.”

With sales of iMAP on the up and multiple enquiries from USA, Russia, China, Singapore, Saudi Arabia, Japan, Israel and the UK, it certainly seems like this new system is changing the way aero engine manufacturers measure and assemble turbine rotors both now and in the future.


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