Posted to News on 29th Apr 2007, 19:02
Cost-effective positioners offer accuracy and versatility
Now available from Micromech is the 402/403XE series of 'economy' positioners that combine a rugged steel body construction with an integrated precision ball screw and bearing guide, all of which results in a highly accurate, cost-effective device suitable for applications in the hard disk, semiconductor, medical, machine building - and many other industries.
To achieve good accuracy, the positioner uses a gothic arch configuration with four points of contact for each ball in the bearing set to ensure smooth motion while achieving high-precision capabilities. It employs an integrated precision screw and guide, the bearing provides a low-profile, high-accuracy, smooth motion, and robust 'adjustment-free' design over the life of the actuator
The designers have chosen a precision ball screw drive train for smooth motion with high accuracy and high mechanical efficiency. The rigid steel U-channel body provides structural rigidity for minimal deflection and is claimed to be significantly stiffer than most aluminium-bodied positioners. This also means savings can be realised through a lighter support structure.
Their low-profile design is the result of using the highly integrated ball screw and guide bearing, which allows for a greatly reduced overall height when compared to traditional stacking of a bearing and screw assembly - and hence a more compact footprint.
Sensing versatility
Flexibility in limit switch options allows customers to chose between a complete limit switch kit assembly and a standard limit switch kit mounted on the side of the tables. This flexibility is further extended with NPN, PNP, normally-open, and normally-closed limit options. With this claimed unmatched design, no pinch points exist between the limit sensors and target. The limit sensor kit design allows the limits to be adjustable along the travel length of the positioner; they are also easily connected, with fewer cables to manage, and are aesthetically pleasing.
The limit/home switch installed is a Hall effect sensor that is tripped by a magnet located in a housing attached to the carriage. On the switch body is an LED to indicate activation; normally-open (NO), normally-closed (NC), current sinking (NPN) and current sourcing (PNP) variations are selectable with the product. Normally-open sensors are typically used for home, and normally-closed are typically used for limits. With a current sinking sensor, the output lead provides a path to ground when activated, and with a current sourcing sensor, the output lead provides a positive (+) voltage potential relative to ground.
The 402/403XE positioners have flexible motor mounting options so that a variety of motors can be fitted, including servo and stepper motors. With standard options for Nema 16, Nema 17 and Nema 23 motors, these actuators allow users to select the motor of their choice without being restricted to one model. To further customise the application, they can be ordered ready to mount most other manufacturers motors as well.
Further options
For added protection from contamination falling into the bearing system and drive train, an optional hard clear anodised cover is available. This bring sthe positioner to an IP20 rating and prevents large particles from entering and damaging the screw or bearings.
When ordered with the cleanroom option, the XE comes factory prepared for most cleanroom applications; along with the cleanroom lubrication, the XE offers an optional Raydent surface coating that protects against rust on the steel components for more than 10 years.
The integrated bearing arrangement, the rigid steel body, the ability to be easily integrated into multi-axis designs and the fact that it is virtually adjustment-free - and it is priced extremely competitively - make the XE series of actuators exceptionally good value.
