With the motorized lead screw actuator (MLA), customers who require precise adjustment movement can simply specify the load, stroke and type of end machining - and have a ready-to-use solution. In a typical stepper motor linear actuator, the load is connected to a nut that moves back and forth as the spindle rotates. To convert the rotary motion of the motorized lead screw into the axial motion required to move the load, the nut must be prevented from turning. Application designers usually realize this by using external guiding devices, but these take up valuable space and also cause additional costs and complexity. The design of Thomson's MLA models presented here eliminates the need for an external guide by encasing the screw in an aluminum tube with cast-in notches that engage the nut to prevent it from rotating. In addition, this design has an integrated bearing bushing that can withstand small radial and moment loads.

The combination of screw drive and stepper motor is a simple and cost-effective method of achieving precise linear motion.

The MLA is ideal for laser-sensitive applications where space is limited and short strokes with high repeatability are required. 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 MLA stepper motor linear actuators are now available for motor sizes Nema eight, eleven, 14, 17 and 23, 1- or 2-stack, with various 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 hole patterns in the Nema standard; customized hole patterns are also available, as are special connection threads, wiring, cabling and connectors. As the lead screw is only located on one side of the motor, devices such as rotary encoders can be easily mounted.

Thomson has been developing drive technology components for over 70 years. The company is a manufacturer of ball bushing linear bearings and profile rail bearings, 60 case shafts, ground and rolled ball screws, linear actuators, gearboxes, clutches, brakes, linear axes and accessories for various markets. pb