Exact Dimensions for a Lot of Power

Pietro Rosa Inspects Turbine Blades with Coordinate Measuring Technology from Carl Zeiss

For 15 years, Italian company Pietro Rosa TBM S.r.l. has trusted in the measuring technology from Carl Zeiss for the manufacture of turbine blades. Since then, quality problems are  non-existent and customers have higher energy yields.

The challenge: critical dimensions and critical customers

Be it a gas or steam turbine, gears on aircraft, ships or wind turbines - the exact form and dimensions of the turbine blade geometry determines power yield. Pietro Rosa's customers meticulously tinker with their dimensions and critically monitor if every single turbine blade meets the specifications. This is why measuring technology is so vital at Pietro Rosa.

However, inspecting the blade dimensions is anything but easy. Although there are relatively large production tolerances of two to three-tenths of a millimeter for the measurement of the "wings," they consist of freeform surfaces that can only be inspected via scanning. The foot of the blades are relatively easy to measure because they are usually cylinders, planes or conical shapes. However, the production tolerances are extremely critical at one or two-hundredths of a millimeter, i.e. 10-20 micrometers. They can only be inspected on machines with a measuring tolerance of no more than one micrometer. In the past, this was a manual process – in other words, susceptible to errors.

The solution: highly accurate coordinate measuring technology

Pietro Rosa has placed its trust in the measuring technology from Carl Zeiss since 1996. The first coordinate measuring machine was quickly selected: back then, the UMC 850 from Carl Zeiss Industrial Metrology was the only measuring machine on the market to feature active scanning technology. The measuring object is continually scanned instead of measured point by point with a stylus. This was the only way for Pietro Rosa to inspect the freeform surfaces of the turbine blades at the time. Since then, Carl Zeiss has continually expanded and improved its measuring technology, measuring machines and software. For this reason, Pietro Rosa has invested in new systems from the metrology experts in Oberkochen on numerous occasions over the past 15 years.

Customer benefit: precision when needed, speed when possible

The investment in coordinate measuring technology has been a success: Pietro Rosa has been able to considerably improve the measurement results and thus guarantee a long service life for the turbine blades for high energy yield. The company's most recent acquisition: an ACCURA II in April 2011. This very flexible coordinate measuring machine enables individual specification of the balance between precision and speed. This enables the Italian company to increase the measuring speed for certain, less critical parts.

About the company

Pietro Rosa is one of the leading manufacturers of turbine and compressor blades for the air and space industry, as well as for the oil, gas and shipping industry. The company is an expert in critical parts for high-performance applications. The material plays a subordinate role – from steel and nickel up to titanium, the Italians have everything in their portfolio. The size of the parts also varies considerably. Pietro Rosa produces blades ranging from just 35 millimeters up to 1.7 meters. Regardless of the size, one thing remains the same: quality inspection is as important as it is complex.