The trends impacting today’s motors and drives are the same as those affecting other manufacturing equipment. One example is the desire for modular products that facilitate integration with existing production lines or are easy to upgrade/replace over time. Customers also demand efficiency. This often means drivers that can handle more axes, motors that deliver more torque and speed, and both doing so in a smaller package.
Another major concern is maintaining safety as production lines increase power and speed of operation. Furthermore, advanced automation and the Industrial Internet of Things (IIoT) are increasing the need for connectivity.
This article examines these changes in the motors and drives market. Specifically, it looks at how four trends are influencing design, connectivity, and safety decisions.
1. Eliminating Line Changeovers
Shutting down a line to change tools or products is costly. Traditional alternating-current (ac) or direct-current (dc) motors can limit features like indexing or handling parts with multiple different sizes on a single line. Modern production lines are increasingly using advanced automation and robotics that benefit from knowing the position or phase of motors.
The servos or stepper motors in robotics can reduce the need for changeovers and advanced equipment downstream. For example, a robotic arm and machine vision can work together to pick and place parts on a conveyor belt in a specific orientation, or separate them based on size or the specific product.
This new information is uniting production lines. Previously, one section of a production line might have driven product to the end of an assembly line, while another, say, packaged the products in boxes. Adding more data communication and control by using servo and stepper motors can reduce hardware and unite a segmented production line.
According to PR Newswire and MarketsandMarkets.com, advanced automation and energy-efficient standards has led to growth for servomotors and drives. The market is expected to rise from $10.26 billion in 2015 to $10.43 billion in 2018. According to Globe Newswire, it will reach $15.92 billion by 2022. Advanced automation and robotics are the key drivers of growth in the servo and stepper motor market, which in turn is leading to smaller, more powerful motors and enhanced drivers.
|Sinochron motor design offers advantages in continuous duty applications without an encoder. Applications can include powering of conveying equipment, escalators, spooling machines, compressors, and traction drive units. ABM Drives’ Sinochron is one example of how continuous motors are competing on efficiency and cost levels (saving up to 35% in energy cost).
Photo: ABM Drives
Servomotors and stepper motors are more expensive than ac and dc motors. Their usage has steadily increased, however, thanks to the benefits that come from advanced automation in applications for indexing or position control. Typically, continuous or free-running motors have specific applications; therefore, servo and stepper motors are unlikely to replace them completely. Overall, each motor has its own applications.
“While motor types are application driven, reduced cost and added features have servomotors turning up in new places,” says John Kowal, director of business development for B&R Industrial Automation. “As servos are reducing in price, case packer design may switch from mechanical devices to servos to index, tuck flaps, and compress cases after gluing. While this increases the axes, it also makes the machine more flexible, reduces labor, and reduces change over time. Format changes become recipe changes that require no tool or change parts. These benefits will outweigh any difference in cost these motors might have. The driver in reducing the cost of servomotors is manufacturing processes and modularity.”
2. Replacing Custom Motors
Many OEMs offer modular designs, which enable them to cost-effectively produce semi-custom servo and stepper motors. In addition, high-speed communication buses make it possible for control systems to handle more axes in an efficient manner. Drivers and feedback devices can further hone a motor. Drivers and software will allow a few motors to satisfy a range of applications.
“Designers have found putting everything on one control platform is the most efficient way to design their code,” says Jim Wiley, Product Manager for servo and stepper drives at Parker Hannifin Corp. “Having flexibility and being able to pick the motors and power size needed, while cramming more electronics in smaller boxes to get more axes in one cabinet, is an important design decision for OEMs.”
There are many design aspects to motors, which can make them difficult to mass-produce. The ability to mix and match standard frames, stators, and rotors with other components offers a balance between cost-effective manufacturing and customization. To streamline and keep manufacturing lean, some companies have automated material handling that will collect materials as they are ordered. With enterprise resource-planning software, the material handler can move the most-ordered parts closer to the drop-off point, quickening acquisition of materials and helping regulate inventory. The end result is you get your motors and replacements faster.
Parts may have to be replaced or upgraded before a component has met its lifecycle. Expectations are for a platform to last for 20 to 25 years. With such a long time span, being able to easily modify the part has obvious benefits. If a standard motor stops working, it will be faster to replace than a custom version.
It is important to know the motors in the equipment you’re buying so that you can anticipate lead times if one needs to be replaced. If an application needs a highly customized motor and there are long lead times, it may be beneficial to have an extra one in inventory or invest in predictive maintenance features. For example, harsh environments often wreak havoc on small, fragile servomotors. This creates a high total cost of ownership, not only due to replacement costs, but also from loss of revenue when production lines are down.
|Weight and temperature in WITTENSTEIN's Cyber dynamic line was reduced by 25% by optimizing the magnetic circuit. This design reduces eddy-current losses and limits magnetic saturation.
Keeping a production line up and running is more important than ever as manufacturers continually look to improve production-line run times. Reducing downtime can seriously impact profit margins on fast production lines. On this front, the market is currently abuzz about the IIoT. Being able to obtain more data about motors, speed, torque, position, temperature, etc., can improve a motor’s lifecycle while reducing errors and downtime. Many companies are trying to justify the cost of new IIoT equipment, though, because it can be hard to monetize this data.
3. Miles of Cable and Slow Productions Lines
Feedback from the motor to the driver, along with reduction of cable, keeps production lines competitive. Feedback improves performance and resolution while providing more information. In the past, protocols in this space have been proprietary and specific to manufacturers, but open protocols like EnDat, BiSS, and Hiperface are becoming more popular because they offer more flexibility and choices. Advanced platforms, which increase the amount of data transmitted and data-transfer speed, are better at sorting out noise. This has made it possible to reduce the number of cables.
|Parker’s MPP (MaxPlusPlus) servo motor features potted stators that improve heat transfer for better thermal efficiency, resulting in increased torque at the motor shaft. Using Hiperface DSL feedback reduces complexity, as there’s only one cable connection between drive and motor.
Photo: Parker Hannifin
In fact, if communication isn’t diminished, customers are now demanding a single cable. Having less cables reduces installation time and cost while keeping or even adding features. At the center of this trend are communication protocols. You don’t want to be locked into a single feedback or communication protocol type, so look for drive manufacturers that offer multiple protocols. This gives designers the option to use the protocol with which they are comfortable or the protocol that works best for a specific application.
“Currently, fieldbuses such as CANopen, Profibus, and DeviceNet are used for various applications. But what has emerged from those different communications as the wave of the now and future is communication based on Ethernet,” says Parker Hannifin’s Wiley. “The hardware is cost-effective and it is in everything. It has become a matter of taking Ethernet hardware and finding a way to fulfill the real-time requirements needed in motion-control and servo-drive applications.”
EtherCAT, Profinet, Ethernet IP, and Powerlink are common ways of communicating from your control to your drive. They all enable high-speed real-time communication while increasing the amount of information that can be passed from the drive up to the control system. “10 to 15 years ago, drive manufacturers would include communication protocols as an add-on or afterthought,” says Wiley. “Today, it is important to design the servo-drive platform around these communication protocols. If you design with this in mind first, you can achieve the performance and cost structure that will help you be competitive.”
CANopen is one of the high-level communication buses that can work well for motor control. This protocol was developed for embedded networking. In one example, Crouzet Motors offers a CANopen communication bus on its brushless motors. Depending on the application, it is possible to control up to 127 motors with a single, shielded two-wire cable. “The CANopen system is a very robust system, ideally suited to motion control, controlling the motor’s position, speed, torque, etc.,” says Robert Derringer, director of marketing at Crouzet Motors.
|The CANopen dc brushless motor from Crouzet Motors lets a single cable run from one motor to the next; the master can address each of the motors separately to control a movement, make an adjustment, or run diagnostics. The image shows the CANopen motor with and without a gearbox. This specific gearbox achieves a 27 to 1 ratio. The CANopen interface permits data to be transmitted at speeds up to 125 kBd up to a distance of 550 yards. Extending this distance is possible (up to three miles) by reducing the speed at which data is transferred.
Photos: Crouzet Motors
By relying on communication protocols, the control units on some motors also can handle multiple safety inputs. In the event of a failure, additional safety inputs can lock the motor power-stage control. This cuts the power supply to the motor windings, sending the motor into a type of freewheel mode. This action does not have to go through the microcontroller, thereby ensuring a high level of safety.
4. Don’t Touch the E-Stop!
Has anyone in your factory hit the E-stop, and in turn make you have to rehome your servomotors before starting production again? Often, the encoder that sends the motor feedback to the drive is responsible for this occurrence. Absolute encoders are popular because they track the motors’ specific position or phase. Power to a motor with an absolute encoder can be shut off and will subsequently start right where it stopped.
An incremental encoder, on the other hand, will only measure what direction and how far the motor traveled. Therefore, incremental encoders need to be calibrated, which takes time, or given a position to restart. If an emergency stop or light curtain is engaged, a motor with an incremental encoder cannot simply resume operation. While emergency stops and light curtains are important for worker safety, stopping production can be costly. This has led to more intelligent drive solutions.
|B&R Industrial Automation came out with a compact, IP65-protection-rated ACOPOSmotor that offers an intelligent safety encoder. With the EnDat 2.2 communication protocol, a securely mounted encoder, and compact size, this motor falls in line with many of the trends seen in industry.
Photo: B&R Industrial Automation
Today, you hear more and more about functional safety. This approach doesn’t cut power from the motor; instead it goes into safe mode that limits speed, direction, torque, and position that allows the machine of line to continue operation at a reduced production rate. These are important design constraints applied by the programmer, and they must follow standards while keeping production moving and enhancing employee safety.
Some encoders have started offering additional mountings, reducing the risk of the encoder coming loose. A robust connection is more important than ever now that feedback information has become so critical to production and safety. While encoders may sound basic, knowing if your motors have an absolute or incremental encoder will be crucial if the motor is occasionally turned off, an emergency stop is engaged, or power is lost for any reason.
As the speed of production lines increases, it is important to maintain worker safety while minimizing downtime. A desire for more safety features and greater use of advanced automation and robotics will continue to strengthen the servo and stepper motor market. The market will be led by motors with higher-level communication protocols and more robust intelligent feedback. Overall, the motor and drive markets are driven by customer demands. Manufacturers that can get more torque, speed, and data in a smaller package for less cost will be more successful.
This article originally appeared in Machine Design.