RSF Elektronic, represented by Heidenhain Corporation, has released the new slim profile linear encoder series MSA 700 and 800 tailor-made for metrology applications which require protection from contamination. Typical applications for these encoders are optical comparators, and video and vision systems. The main advantages offered by these encoders are generous mounting tolerances, low level backlash and optimized thermal behavior. Central to the design of these new encoders is the reading carriage and reading head connected by a wear-free and maintenance-free magnetic coupling. The carriage is also constrained by a magnet guide that affects the ferromagnetic tapes on the extrusion. Hence, there are no forces that could stress guide parts and no contact points that could prematurely wear. Improving upon old roller bearing or spring coupled encoders, the new magnetic coupling and guide eliminates wear and provides even pressure along the measuring length. This combination allows for generous mounting tolerances without any negative influence on accuracy. An additional benefit of this magnetic coupling is the extremely low backlash, reducing one of the main weaknesses of sealed encoders.
The fiber-reinforced sealing lips made of fluororubber (Viton) are wear and coolant resistant, allowing the encoder to operate in harsh environments. High velocities are also possible due to the high degree of rigidity and ideally formed blade area of the reading head. The scale itself is fastened via a flexible adhesive film in the profile, which compensates for the differing linear expansion between the glass and the aluminum. Thus a reproducible thermal growth is ensured by symmetrical expansion or shortening of the scale to the profile. Expansion differences between the aluminum profile and machine slide are accommodated by flexible fastening elements.
This new MSA 700 and 800 series is defined as sealed incremental linear encoders that have grating pitches of 20, 10, and 8 microns, and come in accuracies of 2, 3 and 5 microns. This makes them suitable for customer applications requiring precision and protection. They have the same mechanical footprint and electrical properties of the MSA 600 series, and can be customized to suit customer specifications.