Well, first of all Heidenhain specializes in the production of extremely high accuracy and high quality Linear Encoders and Scales for the machine tool industry.  Heidenhain uses a high quality glass with etched in graduations mounted into a very robust aluminum housing to prevent corrosion.  Now I know what your thinking!  Why would I want to put a glass scale on my machine tool when I can buy a Newall encoder that used steel roller balls?  Then I don't have to worry about things breaking! 

     Well, here is why you should put a Heidenhain glass scale on your machine tool!  First of all Accuracy!  This is a concept that is commonly mistaken for Resolution.  With the Newall version of Steel roller bearings your accuracy is being calculated using sonar technology, which is scanning the varying curvatures of the ball bearings as the reader head moves across the length of the encoder.  While this sounds high tech, it's really not!  Sonar technology has been around for decades.  Also think about it this way.  When you look at buying a Newall scale or encoder try finding the accuracy, most likely the sales rep is only going to tell you about how high the resolution and repeatability are.  Remember the number of graduations on the linear encoder determines accuracy.  Newall uses approximately 1/2" steel ball bearings mounted in a tube.  So from the peak of one ball bearing to the peak of the next you have a total distance (graduation) of about a 1/2", not to mention that’s assuming every ball bearing is exactly machined to the same tolerance.  Heidenhain on the other hand uses a 0% expansion glass with 10-micron graduations etched into it.  So if you have a one-meter linear encoder or scale you'll have approximately 80 graduations on the Newall encoder, and about 100,000 graduations in the Heidenhain encoder.  So it begs the question what are you really getting sold?

     So what about other Linear Encoders and Scales like Accurite, Sony, Mitoya, and so forth?  With other Glass Scale manufactures there is fewer differences compared to Newall, but all there same they are not all a like!  One of the big differences between Heidenhain Linear Encoders and Scales and other Linear Encoders and Scales is both the number of graduations and how the graduations are put on the glass.  Let's talk about how the graduations are put on the glass first.  With Heidenhain the graduations are actually etched into the glass so that no matter what you cannot rub the graduations off.  A lot of the other Glass Scale manufactures us a laminated graduation, which is more or less laminated onto the glass.  Although Heidenhain and the other manufactures may have the same number of graduations per meter, you run a much higher risk of damage to the graduation marks; Mainly, because, the laminated graduations can get faded or removed by solvents and cleaning agents.

     For more information on Heidenhain Linear Encoders and how they functions please view the attached links on this page.  If you have any questions you can always call Powertronics Inc. @ 1-877-571-2325