A ball spline is a type of rolling bearing linear guide, similar to a round shaft and bushing assembly, but with a critical distinction in its operation. The shaft of a ball spline is much like a linear guide shaft, except that the spline shaft has grooves along its length. The spline nut (analogous to […]
FAQs + basics
When should you lubricate a lead screw?
It’s expected that a ball screw, with metal-on-metal rolling contact between the balls and the raceways, will require periodic lubrication with either grease or oil. One of the advantages that lead screws have over ball screws is that they can often operate without lubrication — eliminating maintenance and the potential hazards that come with using […]
How do magnetic linear encoders differ from optical versions?
Encoder technology generally falls into three categories: optical, magnetic, and capacitive, with optical and magnetic encoders making up the bulk of the industrial automation encoder market. Not very long ago, the choice between optical and magnetic technologies was primarily a matter of resolution. If encoder resolution below 5 microns was required, optical was the only […]
When is resolution important for linear systems?
Accuracy and repeatability are standard specifications that describe how a linear motion system behaves along its travel and how closely it reaches the intended position. Resolution, on the other hand, is less often included in performance data for linear motion systems, but it can be equally important as accuracy and repeatability in some applications. In […]
Differential windlass drives: How new designs work for linear motion
Rise Robotics now sells the Rise Cylinder — an electromechanical linear actuator that (according to the company) delivers power density and reliability comparable to or exceeding those of linear actuators based on roller screws and hydraulic cylinders. Rise Robotics is currently working with select partners to bring the actuator to market through commercial production. Shown […]
What type of motor is a servo motor?
The short answer is: There is no single “type” of servo motor. The term “servo” simply means the motor operates in a closed loop control system that uses feedback from an encoder or resolver (typically integral to, or mounted on, the motor) to compare the motor’s actual position, velocity, or torque to the commanded value. […]
Linear motion applications for piezo actuators and piezo motors
Piezo actuators and motors are often the preferred technology when an application requires movements of a few millimeters or less with high resolution. And while these small-scale applications don’t typically attract the same level of attention as those that require massive 100 mm diameter ball screws or enormous 12-meter gantries, applications in the single- and […]
How to calculate the effect of preload on ball screw axial deflection
In a recent post, we looked at the methods for inducing preload in a ball screw assembly and the effects it has on performance. One of those effects is that preload reduces axial deflection (displacement) and increases rigidity. But preload also increases the applied load on the screw assembly and reduces life. To determine the […]
How do magnetostrictive sensors work?
When a ferromagnetic material — such as iron, nickel, or cobalt — is subjected to an external magnetic field, the magnetic domains within the material align, creating internal stresses that cause the material’s shape or dimensions to change. This phenomenon is referred to as magnetostriction. Conversely, when a magenetostrictive material is subjected to a stress, its magnetic […]
How does a rack and roller pinion work?
A rack and roller pinion system is a variation on the traditional rack and pinion that replaces the toothed pinion (gear) with a cage-type pinion that incorporates bearing-supported rollers. Each roller in the pinion is supported by two needle bearings, which eliminates the sliding friction that occurs in traditional rack and pinion systems. This greatly […]