With the new motorized lead screw actuator (MLA), designers of high-precision, short-stroke systems save the cost, time and maintenance associated with developing and manufacturing their own external guidance systems. "The combination of lead screw and stepper motor is a simple and cost-effective way to achieve precise linear motion," explains Markus Brändle, Product Specialist at Thomson. "However, when using simple stepper motor and lead screw assemblies, costly external guide systems with anti-rotation protection usually have to be designed. With our new MLA product line, customers who need a precise adjustment movement can simply specify the load, stroke and type of end machining - and have a ready-to-use solution."

Built-in anti-rotation protection
In a typical stepper motor linear actuator, the load is connected to a nut that moves back and forth when the spindle rotates. In order to convert the rotary movement of the motorized lead screw into the axial movement required to move the load, the nut must be prevented from turning. Application designers usually realize this by using external guiding devices, which, however, take up valuable space and also cause additional costs and complexity.

The model is suitable for laser-sensitive applications with limited space that require rather short strokes with high repeatability. Examples include the adjustment of a microscope stage, the inclination of a computer screen or the vertical positioning of a pipette on a test tube rack. The ideal application has a stroke length of less than 64 millimetres, a load of less than 890 Newtons for any motor size and requires speeds of less than 500 millimetres per second.

The stepper motor linear actuators are now available for motor sizes NEMA 8, 11, 14, 17 and 23, 1- or 2-stack, with numerous options for the motor winding. The achievable linear resolution ranges from 0.002 to 0.191 micrometers linear stroke per step. The actuators are supplied with NEMA standard hole patterns, but customized hole patterns are available as well as special connection threads, wiring, cabling and connectors. As the lead screw is only located on one side of the motor, devices such as encoders can be mounted without any problems, according to the manufacturer. as