How Does a Stepper Motor Work?

A stepper motor is a simple two phase brushless synchronous motor containing a segmented magnetized rotor and a stator consisting of a prescribed number of electromagnetic coils. When energized, these coils create north and south polls that push or pull the segmented magnetized rotor to make it spin. The illustration shows the internal construction and tooth alignment of a typical hybrid stepper motor. The fine teeth, evenly spaced around the entire diameter, provide the incremental angular rotation that results in mechanical motion. 

Stepper motors consist of two windings (2 phase) energized with DC current. When the current in one winding is reversed, the motor shaft moves one step. By reversing the current in each winding, the position and speed of the motor is easily and precisely controlled, which makes the step motor extremely useful for many different motion control applications. The step size is determined by the motor design characteristics, with the 1.8° step angle the most common (consisting of 200 teeth). Other step angles are readily available. The number of steps per revolution is calculated by dividing 360° by the step angle.

Stepper motors are selected by holding torque and corresponding rated current. Holding torque specifies the maximum external torque applied to a motor (energized with its rated current) without causing continuous rotation. At the point the motor begins to rotate, the available torque is often referred to as pullout torque. Pullout torque ratings are represented as values plotted on the motor’s speed/torque curves.

The coils of a stepper motor can be configured in a unipolar or bipolar arrangement. Since simple stepper motor driver electronics can be used to sequence the coils to rotate the motor shaft, unipolar configurations are the easiest to control. A bipolar arrangement requires a more sophisticated driver to properly sequence the windings to control the motor, which also provides additional performance benefits, such as a higher holding torque. 

Stepper drives are available in a wide range of voltage and current ratings. A motor’s performance is highly dependent on the current and voltage supplied by the drive. The terms full-step, half-step, and “microstep” are commonly used to discuss step motors. A 1.8° step motor, for example, has 200 discrete positions in a full 360° revolution. Since 360° divided by 200 equals 1.8°, the motor shaft will advance 1.8° each time the motor is commanded to take one step – known as a full-step. The term “half-step” indicates a 0.9° step angle (half of a full 1.8° step) that is achieved by a switching technique that alternately applies positive current, no current, and negative current to each winding in succession. The term “microstep” refers to a more sophisticated form of control that goes beyond the simple switching of power between the motor phase windings to control the amount of current sent to the individual windings. A major benefit of microstepping is to reduce the resonance amplitude that occurs when the motor operates at its natural frequency. Microstepping permits the shaft to be positioned at places other than the 1.8° or 0.9° locations provided by the full-step and half-step methods. Microstepping positions occur between the two angular points in the rotation of the rotor. The most common microstep increments are 1/5, 1/10, 1/16, 1/32, 1/125 and 1/250 of a full step. 

This blog was a collaborative effort among a team of motion and automation experts  at Kollmorgen, including engineers, customer service and design experts.  

---

 As a Gold Partner, Micromech are able to supply and provide expertise on Kollmorgen products. Contact our sales team on 01376 333333 or sales@micromech.co.uk for price and delivery or technical assistance.   

Disclaimer
The use of this news article and images came with permission from Kollmorgen.

Save up to 70% on ball screw costs

Thomson precision-formed ball screws with P3 accuracy for precision applications 

High-precision processes and precision applications often require ball screws with an accuracy class of P3 and there is a commonly-held view among mechanical design engineers that this accuracy can only be achieved with ground-thread screws.
Now, Thomson offers ball screws with a lead accuracy class of P3 (12 µm / 300 mm) manufactured using our proprietary rolling process called Precision Screw Forming Technology (PST).The advantage of Thomson’s rolled P3 ball screws is while meeting the same precision as ground spindles, they cost up to 70% less.

Their high precision is achieved through several factors:
The selection of the raw material is to precisely defined specifications while our proprietary forming and subsequent heat treatment processes using the latest technology are crucial.The rolling process also results in a stronger material grain structure, so that the screw has a higher fatigue strength and thus a longer service life compared to ground screws.

Features and benefits include: 

• Lengths up to 15 m; diameters of 12 – 80 mm, leads of 5 – 50 mm.
• Maximum dynamic loads up to 480 kN.
• Available with single or double ball screw nuts (flanged or cylindrical).
• Application expertise and advice from the Thomson engineers.
• Customized products – even with smaller quantities; special solutions for harsh environments.
• Thomson Neff Industries GmbH is DIN ISO 9001: 2015 certified.

Ideal applications include: 

• Machining centers.
• Machine tools (turning, milling, grinding, drilling).
• Metal forming, stamping presses, water jet cutting.
• Factory automation.
• Precision industrial robots.
• Manufacturing of electronic assemblies.
• Packaging equipment.
• Medical equipment.

============================================================================

For details of the full Thomson range or for technical help email sales@micromech.co.uk or call 01376 333333. 

Disclaimer
The use of this news article and images came with permission from Thomson.

Kollmorgen Is on the Perseverance Rover — And Extreme Environments Everywhere

From the surface of Mars to the depths of the ocean, from the core of the earth to the core of the human body, Kollmorgen motion systems take on the most extreme environments.

For the vast majority of applications, motors perform in everyday environmental conditions. And while a motor failure may be inconvenient, or even lead to expensive downtime, it rarely causes a catastrophic and irrecoverable failure of the application. Then again, there are specialized, high-stakes applications where the environment is extreme and failure is not an option. Space exploration is the most striking example.

How can you dissipate heat generated by instruments, control electronics and power sources in the vacuum of space? On the flip side of the coin, how can you ensure reliable operation of motion systems when ambient temperatures approach absolute zero? How can you prevent vacuum-accelerated outgassing of materials that could contaminate sensitive components and experiments? How can you ensure that materials withstand the intense radiation from space as well as from the space vehicle’s own plutonium energy source?

Six Decades and Hundreds of Motors in Space

The Perseverance Rover has just begun its mission of at least one Martian year (687 Earth days), and hopefully much longer, exploring the surface of the red planet. It represents possibly the most advanced feat of engineering ever attempted—and it’s just the latest in a long history of remarkable space journeys that Kollmorgen has helped make possible.

Kollmorgen has been supplying motors for NASA programs since the Gemini missions of the mid 1960s and continuing through the Apollo moon landings, the Skylab space station, the GPS satellites that are so critical to everyday life and commerce, Titan rocket guidance systems, the Space Shuttle reusable low-Earth orbiter, and many more. And Kollmorgen motors have been on Mars programs beginning with Viking 1—the first lander to succeed in its mission—through the Spirit, Opportunity and Curiosity rovers, and now the remarkable Perseverance. Over the course of nearly six decades, we have put hundreds of motors into space.

The Heart of the System

Engineering a project like Perseverance is truly a team effort, and we’re proud to be part of the team. Among our many contributions to NASA engineering is a co-engineered RBE Series direct drive frameless motor that drives Perseverance’s critical thermal-management pump, which cools all electronics and instruments onboard the rover. NASA engineers fondly refer to it as “the heart of the system.”

RBE Series motors are ideal for this purpose as the frameless configuration can be integrated directly into the application, using the same bearings to support both the load and the rotor to minimize volume, weight and complexity. The co-engineered RBE design also incorporates materials that can withstand the rigors of space. And a special modification allows for installation of a unique liquid cooling system for the motor itself—designed for reliable, long-term performance under the most extreme conditions.

We are currently working directly with NASA’s Jet Propulsion Laboratory to optimize this co-engineered RBE motor for long-term use on the Europa Clipper Orbiter, scheduled to launch in 2024 and arrive in Jupiter orbit in 2030, where it will map out Europa and other Jovian moons. Our motor will control the pump on the Orbiter’s critical thermal-management system, and is expected to operate throughout a 12-year mission.

What’s Your Extreme Environment?

Supplying motors for space missions may sound exotic, but designing and building motion systems for extreme environments is business as usual for Kollmorgen. And think about it. Extreme environments, where failure is not an option, aren’t just found in outer space or on the surface of Mars. They’re above, below and all around us.

• Kollmorgen motion systems help control flight in everything from commercial aircraft to hypersonic missiles.
• They’re on food and beverage production lines, with hygienic designs built to endure the daily washdowns that can quickly destroy lesser motors.
• They’re in mediCal equipment, from surgical robots to high-resolution CT scanners to implantable devices—such as left ventricular assist devices that literally help keep people alive, healthier, longer.
• They’re deep beneath the Earth’s crust, enduring the extreme temperatures, pressures, corrosives and hazardous atmospheres encountered in oil and gas production.
• They drive and control the robots used to safely remove and replace fuel rods in nuclear power plants.
• Kollmorgen motion systems even help propel and guide underwater vehicles, from the Jason Jr. that explored the Titanic wreck to vehicles designed for the deepest depths that humans and mechanics can go.

And those are just a few of the unclassified programs that we’re allowed to talk about. Don’t see your application on the list? That’s not the point. Kollmorgen has the technology, product range, co-engineering know-how, broad industry expertise and commitment to help you solve practically any motion challenge, no matter what it may be.

Your mission doesn’t need to be searching for evidence of extraterrestrial life. If you’re searching for precise, reliable, perfect-fit motion that you can count on to perform under any conditions, we’re ready to help you engineer the exceptional.

This blog was a collaborative effort among a team of motion and automation experts at Kollmorgen, including engineers, customer service and design experts.  

---

 As a Gold Partner, Micromech are able to supply and provide expertise on Kollmorgen products. Contact our sales team on 01376 333333 or sales@micromech.co.uk for price and delivery or technical assistance.   Disclaimer
The use of this news article and images came with permission from Kollmorgen.

New from Akribis, the DGH range of Linear Stages for the highest precision applications

Overview:

The Akribis DGH series is a range of high precision modular direct drive linear slides utilising a direct drive linear motor positioning system. It consists of dual linear guides, linear motor, encoder feedback and aluminium cover to form a compact high performance module. 

The DGH high performance linear stage series, boast superior specifications and performance to the DGL series, Akribis’ primary linear stage series. The design is highly cost effective focusing on the most crucial elements to provide high precision performance while keeping costs low. 

To meet the challenges of the future for greater precision and quality, the DGH design is the product of improved fabrication capabilities, data-driven selection of precision grade components and the collaboration of specialists in the different fields.

To match the power that a DGH motors can produce, safety is a focus in the range design. The DGH design underwent rigorous testing during its development to meet the increasing expectations for safety while maintaining a high load capacity to max velocity ratio. In addition, the safety feature was developed and sized with the intention of combining multiple Akribis’ modules for a multi-axis stage without sacrificing load capacity.

The DGH series’ electrical components are UL certified and capable of handling the high stresses generated by the powerful motion.

Similar to the DGL range of linear motors the DGH linear motors use the Akribis patented AUM series ironless linear motor or the AJM and AKM series iron core linear motor. 

The AUM linear motor is cogging free, lightweight, with zero attraction force allowing for precise position and velocity control applications such as scanning.

The AJM and AKM linear motors are iron core, suitable for point-to-point motion and provide a more cost-effective solution.

The DGH series is available in range of body widths: 150mm, 180mm, 200mm and 260mm with useable strokes between 100mm to 800mm in 100m increments. Larger strokes are available on request. 

Options:

• Encoder type
• Housing finish
• Ironcore or ironless linear motor
• Flying leads or DSUB termination

In addition to the standard DGL range, the motor stages can be customised in a variety of ways to suit OEMs and repeat customers.

For more information on Akribis products and possibilities, contact Micromech on 01376 333333 or email sales@micromech.co.uk.  

Disclaimer
The use of this news article and images came with permission from Akribis.