球,导致螺丝是指定的直径of the screw shaft and the lead (or, in some cases, pitch) of the screw thread. The lead, which specifies how far the nut travels for each revolution of the screw, is created by the thread, or helix, that wraps around the screw shaft. If the […]
How to calculate duty cycle and what it means for machine life
Determining the life of a linear system that uses balls or rollers is relatively straightforward, thanks to the L10 bearing life equation, which gives life in meters of travel (for linear bearings) or revolutions (for screws). And for plain bearings and lead screws, manufacturers typically use the bearing’s PV value and operating conditions to provide an […]
Comparing micropositioning and nanopositioning stages
Linear stage designs can range from long-stroke, high-load gantries to micropositioning and nanopositioning stages with light payloads. Although all linear stages are designed and constructed to provide high positioning accuracy and repeatability and to minimize angular and planar errors, stages for micropositioning and nanopositioning applications require additional considerations in component selection and design to achieve these […]
What is an inverted roller screw and how does it work?
Roller screws are often thought of as the standard planetary design, but several variations exist, including differential, recirculating, and inverted versions. Each design offers unique benefits in performance capabilities — load capacity, torque, and positioning — but the inverted roller screw’s primary strength is its ability to be easily integrated into actuators and other subassemblies. Recall that […]
What are piezo flexure stages and how do they work?
Piezo actuators provide highly responsive, rapid movements, but their displacement is limited to just 0.1 to 0.2 percent of the actuator length. To overcome this limited stroke capability, a piezo actuator can be combined with elements, such as flexures, that provide mechanical amplification. The amplification provided by a flexure mechanism can extend the stroke of […]
Linear bearing basics: Surface roughness, texture, and finish
One of the factors to consider when selecting shafts for linear bearings is surface roughness, which describes the microscopic asperities, or peaks, and valleys present on a material’s surface. But surface roughness is an important specification for all types of linear guides and screws — whether plain or recirculating, round shaft or profiled rail, ball […]
What are piezo actuator creep and drift?
Piezo actuators exhibit a linear* relationship between applied voltage and displacement, responding almost instantly to any change in voltage. But they also experience creep — a phenomenon in which the actuator continues to expand or contract even after the voltage change is complete. Piezo actuator creep Creep occurs because piezoelectric materials have an asymmetric charge […]
Screw handedness: When do you need a left-handed screw?
Just like people, ball and lead screws can be either right-handed or left-handed. But in screw terminology, handedness indicates the direction in which the nut moves relative to the direction of the screw’s rotation. By far the most common version is the right-handed screw, in which the nut moves toward you when the screw is […]
What is torque ripple and how does it affect linear motion applications?
Motors produce torque and rotation through the interaction of magnetic fields in the rotor and the stator. In an ideal motor — with mechanical components that are perfectly machined and assembled and electrical fields that build and decay instantaneously — torque output would be perfectly smooth, with no variations. But in the real world, there […]
What does bandwidth refer to in the context of servo systems?
Most people are familiar with bandwidth as it relates to networking and WiFi service — for example, the 2.4 GHz and 5 GHz frequency bands on which WiFi signals are transmitted. But bandwidth also plays an important role in servo control and tuning. The bandwidth of a servo control system indicates how quickly the system […]
Troubleshooting V-belt wear and failure
虽然有十多个病人的症状remature wear and impending failure for V-belts — ranging from visible damage to audible noise — there are a few key ways that these friction-based belts can fail during operation. To help users determine the root cause of a failure or signs of potential failure, V-belt […]
When are stepper motors paired with ball screws (rather than lead screws)?
Stepper motors are widely used in industrial and consumer applications ranging from packaging equipment and medical devices to 3D printers and vending machines. They have excellent torque production at (relatively) low speeds — especially for a given motor size — and offer high-resolution positioning in a simple-to-use format. These benefits make them well-suited to drive lead […]
What do the belt section designations H, J, K, L, and M mean for ribbed V-belts?
V-belts rely on friction caused by the “wedging” of the belt between pulley flanges — together with internal fiber cords — to transmit power in a wide range of industrial and consumer-goods applications. One variation of the traditional V-belt is the ribbed V-belt — also referred to as a V-ribbed, poly V, or serpentine belt. Ribbed V-belts take […]
The top 10 linear motion articles of 2021
In our 2020 recap of the most-read linear motion articles, we noted how our readers went “back to basics,” with articles about fundamental engineering topics dominating the list. That theme continued in 2021, but this year, the dominant articles dealt not only with engineering basics, but more specifically with “how to calculate” topics. And although […]
What is a split bridge system and how does it differ from a gantry?
Multi-axis linear systems come in a variety of designs, with Cartesian, gantry, and XY tables being some of the most common types. While these designs simplify construction and can provide space savings, they also introduce “stacking” errors — the compounding of errors from each axis, which manifests at the work piece or tool point. Mounting axes […]
What are the benefits of six-row linear bearings
The most common types of recirculating linear bearings use four rows of balls — two on each side of the bearing block — to provide good load capacity and rigidity. But the four-row design means that when radial (downward or liftoff) or lateral (side) loads are applied, only two rows of balls are engaged to support […]
Contact angle: What is it and how does it affect linear bearing performance?
In profiled rail linear guides that use balls or rollers, the geometry and arrangement of the bearing raceways play a significant role in the bearing’s load capacity, friction, rigidity, and ability to withstand errors in mounting. But there’s another aspect of a bearing’s design that also plays a role in its load capacity and rigidity […]
How to choose a lubricant for recirculating linear bearings
所有的金属对金属介面人工髋关节循环bearings require lubrication in order to function properly and provide a reasonable bearing life. Lubrication reduces friction and heat by separating the rolling elements from the bearing raceway, inhibits corrosion, protects bearing surfaces from contamination, and helps seals run smoothly and operate effectively. Although the importance of lubrication is clear, choosing the best […]
Open aperture voice coil stages with 1.20 inch travel and 25.4 micron resolution
Moticont’s HCDS-051-064 series of open aperture voice coil stages are linear DC motor driven stages. Designed for closed loop servo operation, an integral quadrature optical encoder with differential outputs is standard. The stages are clean, quiet, and efficient, with low inertia, high acceleration, and high speed. Each stage has a built-in home switch for accurate […]
Causes of tooth shear in synchronous belts, and how to avoid it
Synchronous belts transmit power via positive engagement between belt teeth and pulley grooves, making them suitable for applications that require high torque and making them less prone than traditional V-belts to slip in dynamic applications. But even synchronous belts can experience failure if they’re not installed, maintained, and applied properly. One way that toothed belts […]
What are common applications for hybrid stepper motor linear actuators?
When it comes to electromechanical linear actuators, integrated designs offer space savings, reduced complexity, and lower total cost of ownership with fewer parts required for repair or replacement. One such design that’s found multiple uses in medical, 3D printing, and assembly applications is the hybrid stepper motor linear actuator, which combines a ball or lead […]
How axial and radial loads affect linear motion systems
In any motion system, understanding the type and direction of applied and resultant loads is important for determining bearing life and analyzing deflection. In linear motion systems, we typically use Cartesian coordinates (X, Y, and Z) to define the placement and direction of loads. But for rotating components such as screws, rack and pinion drives, […]
Piezo motors vs. voice coil actuators for micron and sub-micron positioning
Applications that require micron or sub-micron level positioning with extremely smooth motion and control often call for a direct drive system — linear motor, piezo motor, or voice coil actuator. Linear motor stages are typically used when high forces are needed over stroke lengths greater than a few hundred millimeters. But for high-precision applications with […]
How to account for rack and pinion inertia during system design
Rack and pinion drives are often used in applications that require stroke lengths beyond the practical limits of ball screws and thrust forces that exceed the capabilities of belt drives. And in some applications, rack and pinion systems can also provide lower total inertia than a suitable ball screw or belt drive alternative, which can […]
Linear motion basics: 13 fundamental topics you need to know
Whether you’re new to designing and sizing linear motion systems, or you could just use a refresher, we’ve gathered all the articles that cover mechanical concepts used in linear motion systems and put them together here, as a sort of “linear motion basics” reference guide. Unlike our curated lists of articles that address sizing and […]