Stepper motors are inherently open-loop devices. They don’t require feedback because each pulse of current delivered by the drive equals one step of the motor (or a fraction of a step, in the case of microstepping). And with small step sizes, or step angles, the motor’s position can be determined very precisely without the need […]
What is Abbé error and how does it affect linear systems?
When evaluating the accuracy of a linear motion system, the area of focus is often the positioning accuracy and repeatability of the drive mechanism. But there are many factors that contribute to the accuracy (or inaccuracy) of a linear system, including linear errors, angular errors, and Abbé errors. Of these three types, Abbé errors are probably […]
Follow these four tips when using L10 life to size linear bearings
The well-known bearing life equation, often referred to as L10 life, is a fundamental element in the sizing and selection of recirculating linear bearings. Through statistical analysis and real-world testing, the L10 life equation can predict, with 90 percent reliability, the life that a recirculating bearing can be expected to achieve. But even this universally […]
What’s the difference between backlash and hysteresis in linear systems?
In linear systems, backlash and hysteresis are often referred to as the same phenomenon. But while they both contribute to lost motion, their causes and methods of operation are different. Backlash: The enemy of linear systems Backlash is caused by clearance, or play, between mating parts, which introduces a dead band when the direction of […]
When did the most common linear-actuator options come about?
This is the first of several technical notes on the technology known as moving coil actuators. Here we provide a brief history of linear actuators used in automation — and hint at where moving coil actuators are suitable. By Ed Neff • President | SMAC Moving Coil Actuators (MCA) Hydraulic actuators came first. These devices […]
Why are planetary gearboxes preferred for servo applications?
In a servo application — one in which a feedback device is used to control torque, position, or speed of a linear or rotary system — the ratio of the load inertia to the motor inertia is a critical factor in system performance. A lower inertia ratio allows the motor to more precisely control the load […]
How to size a rack and pinion drive
In linear motion applications, ball screws are widely recognized for their ability to provide high thrust forces, while linear motors are gaining market share in high-speed applications, and belt drives continue to maintain their reputation as the best solution for long travel lengths. But rack and pinion drives are the often-overlooked workhorses behind gantry and […]
What are walking piezo motors?
Piezo motors that produce linear motion include linear ultrasonic piezo motors, linear stepper piezo motors, and piezo inertia motors. Although their construction and principles of operation are different, all three designs harness the inverse piezoelectric effect — in which a piezo material expands or contracts when electrical energy is applied — to produce linear movement in a […]
What are some considerations for linear actuators in contaminated environments?
Reliable motion is often difficult to obtain when the operating environment is heavily contaminated with debris, or contains extreme conditions such as a wide temperature range or other environmental factors.The use of machinery for operations such as cutting, welding, and material processing often generates a substantial amount of debris contamination. Equipment that is not designed […]
Where are glass scale linear encoders used?
Linear encoders are generally classified by their scanning technology — optical or magnetic. Magnetic encoders use a metal scale (often referred to as a “tape”), while optical encoders use a scale made of either metal or glass. Although magnetic encoders have seen great improvements in resolution and accuracy in recent years, for single-micron and sub-micron […]
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