Coordinate measuring machines ensure the quality of high-quality screw compressors

From Testing to Knowing

As the centerpiece of cooling systems, screw compressors from GEA Refrigeration Germany GmbH generate the necessary temperatures and are part of the process chain in which natural gas is liquefied for transport. In order to ensure and improve the quality and energy efficiency of its compressors, the company uses three ZEISS coordinate measuring machines, including an MMZ T gantry machine equipped with a rotary table.

The challenge: high precision for large workpieces

Natural gas must be cooled to minus 163 degrees Celsius to turn it into liquefied natural gas (LNG). As a result, its volume is reduced by a factor of 600, which allows it to be transported without taking up much space. The extra large screw compressors from GEA Refrigeration Germany are part of the gigantic compressor systems. The heart of the compressors are two screw-shaped rotors that compress gases. The performance and energy efficiency of the screw compressors depends largely on the these rotors optimally interacting. This requires highly precise production with tolerances between -0.02 and 0.01 mm. "Without the appropriate measuring machines, this would not be possible," emphasizes Harald Wilke, Quality Department Manager at GER Refrigeration Germany.

Solution: MMZ T gantry measuring machine

GEA introduced a ZEISS MMZ T gantry measuring machine in October 2013 for the precise quality inspection of large workpieces. The coordinate measuring machine offers a measuring range of almost 16 cubic meters and measuring accuracy of just 2.8 micrometers. It is not an off-the-shelf measuring machine, but was specially configured for the Berlin-based company: it features a rotary table and a tailstock which uses a bezel to very precisely hold the two-ton rotors in the axis during the measurement.

Benefit: exact results at the push of a button

According to Wilke, "This machine is designed for the precise measurement of our complex and large parts." Coordinate measuring machines have eliminated time-consuming coupling: with this process, many manufacturers still use gauges to identify the two rotors that fit to each other within the specified tolerances. Ever since GEA began measuring with coordinate measuring machines, each rotor in a line is the same as the next. Thanks to the measuring machines, ZEISS CALYPSO and GEAR PRO measuring software, the company now determines the source of errors at the push of a button and can initiate the elimination of problems wherever they may be. Wilke's summary: "As quality managers, we are now more than just checkers, we are knowers and controllers – and this makes our entire company that much stronger."

About the company

Throughout the world, the cooling technology of GEA Refrigeration Germany GmbH ensures the availability of the temperatures required in the industrial facilities of the foodstuffs industry, the leisure industry and companies in the chemical, petrochemical and pharmaceutical industries. The 260 employees of GEA Refrigeration Germany GmbH in Berlin and Halle manufacture high-performance, energy-efficient screw compressors. The company belongs to GEA Refrigeration Technologies and is a member of the global GEA Group.