Due to its detachable ceiling, complete machine tools can be lifted into the climate chamber by crane.Due to its detachable ceiling, complete machine tools can be lifted into the climate chamber by crane.
Fraunhofer IWU
Machine tools are sensitive to heat; and environmental effects such as temperature changes, draughts or humidity can seriously compromise their precision. Most companies manufacture worldwide in environments without air conditioning, resulting in machines operating imprecisely and producing rejects. Operating drives and other heat sources such as hot tools can also have a negative effect. In a recently inaugurated climate chamber, researchers at Fraunhofer IWU in Chemnitz, Germany, are studying the influence that climate conditions and ambient interactions exert on machine tools and their components. "Exposure to sunlight and draughts causes thermal interactions in the form of structural stretching, which we are able to reproduce in the environmental chamber. The aim is to stabilise and enhance machine precision directly via a machine control system by correcting thermally-induced errors during operation," explains Dr. Janine Glänzel, a researcher at Fraunhofer IWU.
Thermal influences particularly affect machines with long beds or vertically structured systems, for example, because they accumulate heat asymmetrically during operation and bend to one side. In the new test laboratory, temperatures of 10 to 40 degrees Celsius can be configured with a tolerance of plus/minus 0.1 Kelvin, and air humidity of 10 to 90 percent with a tolerance of 3 percent. Due to its surface area of 40 square metres, a vertical clearance of 4.5 metres, and a detachable ceiling, the chamber is large enough to fit not only individual components, but also complete machine tools, which are lifted into place by the hall crane. The temperature-controlled flooring is designed to support a maximum weight of 20 tonnes.
Thermal analysis of weak spots
Temperature sensors are used to measure the influence of internal and external thermal loads on the machine structure, and temperature fluctuations are automatically mapped. The behaviour of machine tools under long-term exposure can also be gauged. This means manufacturers and users alike can configure their machine tools in advance, and adapt them to future ambient conditions. When displacements actually arise, the researchers implement corrective algorithms they have developed themselves to influence production precision. The measured values are integrated into the corrective process. In addition, the researchers determine the level of heat dissipation from the machine tools in order to feed the heat back into the cooling system and thereby save energy.