Ball and lead screw assemblies are often driven by a motor connected in-line with the screw shaft via a coupling. While this mounting arrangement is simple and easy to service, the addition of a non-rigid mechanical component (the coupling) can introduce windup, backlash, and hysteresis — all of which affect positioning accuracy and repeatability. The […]
Acme or trapezoidal? What’s the difference between lead screw designs?
In power transmission applications, there are two primary types of screw drives: those that use recirculating balls or rollers, for applications that require high rigidity, excellent positioning accuracy, and high duty cycles, and those that rely on sliding contact, for applications that require corrosion-resistance, self-locking operation, and customizable nut designs. The second category — screw […]
Electromagnetism basics for mechanical engineers
Electromagnetism — the relationship between electricity and magnetism — is the underlying principle for the operation of electric motors, as well as generators and transformers. And even though most of us aren’t designing motors (or generators or transformers) from scratch, it’s helpful to have a basic understanding of the concepts and laws that drive their operation. […]
What’s the best timing belt tooth profile for high-speed applications?
Synchronous belts (also referred to as timing belts) are used in a wide range of power transmission and transport applications that require good positioning accuracy. Tensile cords molded into the belt material help eliminate or minimize belt stretch, and positive engagement between the teeth of the belt and the pulley make synchronous belts less likely […]
What you need to know about corrosion-resistant linear guides
Recirculating ball and roller guides are the backbone of many automation processes and machines, thanks to their high running accuracy, good rigidity, and excellent load capacities — characteristics made possible by the use of high-strength AISI/ASTM 52100 chrome steel (commonly referred to as bearing steel) for the load-bearing parts. But because bearing steel isn’t corrosion-resistant, […]
Linear Motion Tips – Top 10 articles of 2019
Linear motion publications are typically dominated by topics related to linear guides, ball screws, and lead screws. But looking back at this site’s most-viewed articles in 2019, it’s obvious that while these are important technologies in the world of linear motion, they’re not the only things our readers are interested in. Case in point: In […]
Stepper motor torque and speed characteristics explained
Stepper motors have different torque-speed characteristics depending on whether the motor is starting/stopping or already running. These characteristics are depicted in two curves on the motor’s torque-speed chart, and it’s important to understand the differences between these curves and what each one means for the motor’s operation. But a stepper motor can also produce torque […]
Part 2 – What is racking in gantry systems, and how can it be avoided?
In Part 1 of this post, we looked at various methods of driving the X axes in gantry systems and how the drive method can influence the gantry’s tendency to experience racking. Another factor that can cause racking in gantry systems is lack of mounting accuracy and parallelism between the two X axes. Racking is the common name […]
What is racking in gantry systems, and how can it be avoided? (Part 1)
Gantries differ from other types of multi-axis systems (such as Cartesian robots and XY tables) by using two base (X) axes in parallel, with a perpendicular (Y) axis connecting them. While this dual X-axis arrangement provides a wide, stable footprint and allows gantry systems to deliver high load capacity, long travel lengths, and good rigidity, […]
Mechanical properties of materials: stiffness and deflection
In a previous post, we looked at the stress-strain curve and its relationship to various aspects of material strength — tensile strength, yield strength, and fracture strength, for example. And while we often think of materials and structures in terms of strength, technically, “strength” is a measure of how much force a material can withstand […]
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