Heidenhain: Absolute Angle Encoder Modules (MRP 8000 Series)

The term angle encoder is typically used to describe encoders that have an accuracy of better than ± 5“ and a line count above 10000. In contrast, rotary encoders are encoders that typically have an accuracy of more than ± 10“. Angle encoders are found in applications requiring precision angular measurement to accuracies within several arcseconds.

Examples:

Absolute Angle Encoder Modules

Angle encoder modules from HEIDENHAIN are combinations of angle encoders and high-precision bearings that are optimally adjusted to each other. They are characterized by their high degree of measuring and bearing accuracy, their very high resolution, and the highest degree of repeatability. The low starting torque permits smooth motions. Due to their design as completely specified and tested composite components, handling and installation is very simple.

Setup

Since HEIDENHAIN manufactures the bearings as well as the encoders, the two functional assemblies are highly integrated. Fewer components are necessary than in conventional solutions, resulting in fewer joints. This permits a very compact and rigid design, with particularly low overall heights. Currently, angle encoder modules with hollow shafts of 35 mm and 100 mm are available.

Properties

The rolling bearings used are specifically adapted to the requirements of high precision rotary axes. Distinguishing features are very high guideway accuracies, high rigidities, low starting torques, and constant continuous torques. At the same time, value was placed on compact dimensions and low mass where possible. High speeds and a high load rating are not of primary importance. The encoders fulfill the requirements for metrology applications. Their most important features are very high resolution, excellent signal quality and best repeatability, even when operating temperatures vary. Incremental or absolute encoders can be used as required.

Advantages

Angle encoder modules are a combination of bearing and encoder. HEIDENHAIN has already completed the necessary assembly and adjustments. This means that the properties of the angle encoder modules have already been defined and tested according to the customer’s specifications. Simple mechanical interfaces eliminate all critical mounting processes. Not only does this significantly ease the installation, but it also ensures that the specified accuracy is attained in the application. The elaborate matching of all individual components to each other as well as to the machine environment is not necessary, nor is the time-consuming testing.

Reproducible guideway accuracy - A decisive property of the bearing

Without question, the absolute guideway accuracy of an unloaded air bearing is better than that of a rolling bearing in many cases. However, in many applications the highest possible reproducible guideway accuracy of the bearing is decisive. When this aspect is considered, angle encoder modules can truly be an alternative to axes with air bearings, since the repeatability of rolling bearings from HEIDENHAIN is comparable to the guideway accuracy of an air bearing. Furthermore, the rigidity of rolling bearings from HEIDENHAIN is greater than that of similar sized air bearings by at least a factor of 10. This means that they are actually the more exact solution for axes under load. In addition, rolling bearings are in general less sensitive to shock loads and do not require a regulated air supply—so they are more robust and simpler to handle.

Areas of application

The angle encoder modules are designed for low to medium shaft speeds and medium loads, with high to very high bearing accuracies as well as the highest degree of repeatability. They are suited to the specific requirements of metrology applications. Typical applications therefore include laser trackers for metrology, high precision rotary tables in measuring machines, and wafer-handling machines in the electronics industry. They can also be used on machine tools where only slight loads occur, such as on electrical discharge machines or in micro-precision manufacturing.

Practical solutions

The MRP 5000 and MRP 8000 series presented in this Product Overview can be adapted for customer-specific modifications. These include the mechanical mounting conditions, individual adjustments to the bearing regarding the demands of the application (pre-tensioning, lubrication, contact angle, materials, etc.), as well as the measuring standard and the electrical interface to the subsequent electronics.

Model No.: MRP 8010, MRP 8080