When we think of stiffness, we often think of mechanical stiffness — the ability of a part or system to resist deflection. But in servo-driven motion systems, stiffness can also refer to how the system is tuned — that is, how the gains in the servo controller are set and, correspondingly, how the motor responds […]
How to avoid wave spring fatigue in dynamic applications
Wave springs are gaining acceptance in motion applications, thanks to their ability to provide similar force and deflection characteristics to traditional coil springs, but with significantly reduced working height. Although wave springs can be used in static applications — such as preloading a bearing or mechanical seal — many applications require dynamic movement — for example, […]
What are some common wave spring material and finish options?
There are four key criteria for sizing and selecting a wave spring: load, working height, physical design requirements (bore diameter, ID, OD), and material. In many cases, manufacturers supply custom wave springs in “exotic” materials or with special finishes to meet unique application demands, including difficult environments or corrosion resistance. And in some cases, appearance also […]
How are industrial shock absorbers different from other damping systems?
Shock loads are common in industrial equipment — both as a normal result of the application and as unforeseen loads that occur when there’s a variance in the operation or process. Whether incorporated into the initial design or added after implementation, industrial shock absorbers are often the best choice for mitigating the forces that result […]
How do cycloidal gears work and where are they used?
One way to classify gears is by the profile of the gear teeth: involute, cycloidal, or trochoidal. (Note that trochoidal gears are used primarily in pumps.) The majority of gears used in motion control applications — including spur, helical, and bevel designs — are involute gears. However, cycloidal gears are a good choice for motion control […]
What is a DC bus choke and why is it used?
In a recent post, we looked at motor chokes — inductive devices installed between a drive and motor — and why they’re used in servo systems and variable frequency drives. But in variable frequency drives (VFDs), inductors can also be placed after the drive’s input diodes, between the input rectifier and the DC bus link. […]
What is a motor choke and why is it used?
A choke is a passive device that adds inductance to a circuit. Inductance is a property of a coil of wire that resists any change to the current flowing through it. (Straight wires also possess a small amount of inductance.) In other words, if current through the coil increases, the magnetic field of the coil […]
What is a constant voltage drive for a stepper motor and when is it used?
There are two fundamental types of stepper motor drives: constant voltage drives, which supply a fixed voltage to the motor, and constant current drives, which manipulate voltage to ensure that a constant current is delivered to the motor. Stepper motor electrical basics The most fundamental equation governing the behavior of a stepper motor is Ohm’s law, […]
What is a sine encoder (aka sine-cosine encoder)?
A sine encoder is similar to an incremental encoder in design and function. Both devices measure either rotary or linear position changes and direction, and both are available with either optical or magnetic sensing technology. The primary difference between the two is that sine encoders supply position and direction information as 1 Volt peak-to-peak (1 […]
How are fast Fourier transforms used in vibration analysis?
Fast Fourier transforms are mathematical calculations that transform, or convert, a time domain waveform (amplitude versus time) into a series of discrete sine waves in the frequency domain. Machine vibration is typically analyzed with measurements of the vibration frequency, displacement, velocity, and acceleration. The latter three — displacement, velocity, and acceleration — are time domain […]