HEIDENHAIN sealed linear encoders with innovative TRUE IMAGE TECHNOLOGY keep on delivering accurate position feedback within machine tools, even when their scales are exposed to condensation and other liquid contamination. How does this work?
This animation explains how TRUE IMAGE TECHNOLOGY for HEIDENHAIN encoders ensures dependable position feedback in the face of condensation and other liquid contamination on the scale.
Coolant is a challenge for encoders
Coolant is essential for many machining processes. By cooling down tools and workpieces, and by flushing away chips, it helps ensure reliable machining processes and results. But coolant can pose a problem for the encoders of a machine tool by exposing them to condensation and other liquid contamination.
Light scattered by the droplet
Droplets refract light
If condensation or drops of coolant settle onto the encoder's scale, then a distorted image of the graduations appears on the photosensor during scanning. The parallel light rays from an LED in the scanning head are refracted within the droplet, much as a raindrop refracts light on a windshield. The resulting light is scattered, casting a wide, ring-shaped shadow onto the photosensor and distorting the appearance of the graduations in the middle. As a result, exact position measurement becomes more challenging.
Light-guiding element keeps light rays parallel
A special light-guiding element located behind the scale, and thus between the graduations and the photosensor, lies within the light beam and eliminates the refractions caused by the droplet. The photosensor receives a clear image of the graduations and can now provide position feedback despite liquid contamination.
Clear scanning with TRUE IMAGE TECHNOLOGY
Zero malfunctions despite increasing contamination
HALT tests prove the technology's effectiveness
How does a scale's liquid contamination behave during operation? And how do encoders with TRUE IMAGE TECHNOLOGY react to increases in contamination? Answers were provided by various Highly Accelerated Life Tests (HALT) performed with sealed LC and RCN enocders and the light-guiding element. Even without purge air, and despite ever increasing contamination, the position signals remained error-free during scanning. After more than 1000 hours of testing without a malfunction from either encoders, the tests were eventually ended due to the time limit under full functionality.
"Encoders that operate reliably and accurately under all conditions keep our machines running properly at our customers, ensuring minimum Total Cost of Ownership and maximum sustainaiblity."
Ferruccio Bonardi, BTB Transfer SPA
Reduced carbon footprint and TCO with TRUE IMAGE TECHNOLOGY
Reliable position feedback without sealing air
Sustained high producitity through contamination-resistant optics
Fewer machine components due to simplified purge-air system
