Endress+Hauser Wetzer GmbH + Co. KG, located in Nesselwang, Germany, highlights the interior as well as the exterior quality of its products using precision lettering that is always identical. Yet in 2005, the company was faced with a true challenge that took Willi Hailer almost three years to solve. Demand from America and Asia jumped, and at Endress+Hauser, the company policy was that a customer order had to be shipped within 48 hours. So management decided to build new production facilities in Greenwood, USA, and Suzhou, China. But products from these new facilities were to be undistinguishable in quality or appearance from those produced by the parent company.

The latter proved to be impossible: Different lasers along with their operators would always produce more or less differing results. Yet units produced overseas are also assembled using components from Nesselwang. "Different lettering is quickly noticed and easily gives the impression that parts of varying quality were used," says Willi Hailer.

Willi Hailer and his colleagues believed the solution lay in a centralized laser control unit that stores all layouts together with control information such as output, pulse frequency and track width for the marking laser. Yet the plan collided with so-called “scattering” of laser sources. The output of a beam is controlled by the electricity that powers the beam source. However, the intensity of the laser light does not decrease at exactly the rate at which the operator or the control software decreases the electrical energy. At half the electrical output, the beam delivers just about half the laser output. The actual value is just above or below 50 percent.

This means that the same parameter set generates slightly different lettering on different machines. The phenomenon is well known and manufacturers are keep-ing this scattering — different from manufacturer to manufacturer — within narrow bandwidths. All of this is no problem as long as it has to do with individually func-tioning stations operated by experienced employees. Yet Hailer wanted to control multiple lasers with different output curves via fixed parameter sets. And he wanted to expand the combination at any time or be able to easily replace lasers.