Featured - Motion Control Tips

Servo drive controls highly dynamic processes with greater precision

March 26, 2019 By Miles Budimir Leave a Comment

With the latest upgrade to its ACOPOSmulti multi-axis servo drive, B&R now enables even shorter cycle times down to 50 μsec. Highly dynamic processes can now be controlled more precisely than ever.

For demanding motion control applications, such as those found in the printing and packaging industries, movements must be controlled quickly and precisely. The ACOPOSmulti’s short cycle time of 50 µsec for current, speed and position control opens up new possibilities for virtual sensor technology.

Using a virtual motor position encoder eliminates the need for an encoder, encoder cable and evaluation unit in the servo drive and at the same time increases availability. Other special functions for more precise control and faster reactions can be implemented using virtual sensor technology. These include model-based control with autotuning and a repetitive control function for predictive lag error compensation.

For more information, visit www.br-automation.com.

VFDs with integrated PLCs for motion and machine controls: Programming and setup considerations

March 24, 2019 By Lisa Eitel Leave a Comment

Today’s ac drives can be controlled by either an external or internal PLC. Those with built-in controls move machine intelligence to the edge.

By Jeff Payne • AutomationDirect

Though ac drives can operate in standalone, they often integrate into automation systems to control speed of three-phase ac motors that commonly run conveyors, fans, and pumps. For such speed control, ac drives most often pair with PLCs. But ac drives are becoming more intelligent … and some now include built-in PLCs to work as smart drives. These smart ac drives are compact; add intelligence at the edge of machinery; include inverters capable of more than just typical speed control; and accept the setting of myriad parameters.

In this feature, we’ll detail how to integrate smart ac drives and the applications for which they make the most sense.

Many VFDs, such as this AutomationDirect DURApulse GS4 series AC drive, can be controlled and monitored by an external PLC.

Review of how ac drives work

An ac drive is often called a variable frequency drive (VFD), adjustable frequency drive (AFD), or frequency inverter. We use the term VFD for its main function of varying the speed of a three-phase ac induction motor. VFDs also provide motor overload protection, non-emergency starting and stopping, and control of acceleration and deceleration.

VFD benefits significantly boost the efficiency of many applications. In addition, they gradually accelerate the motor — which in turn reduces inrush current during motor startup. This minimizes both electrical and mechanical stress on the system.

VFDs operate by rectifying incoming ac power to dc and then inverting it back into three-phase ac output power. The voltage and frequency of this inverted output is controlled by the drive to vary the speed of a three-phase ac induction motor.

Control modes include volts per Hz (V/f), V/f with encoder, open-loop vector, and closed-loop vector control. These methods all use a pulse-width modulation (PWM) voltage waveforms; they’re well-developed motor control methods needing some level of automation to control the drive.

VFD control methods

A VFD is controlled by discrete inputs (two or three-wire control), analog inputs and/or digital communications. In its simplest form, a VFD can be manually controlled using the built-in digital keypad’s run/stop buttons. This keypad also allows setting of the drive speed and other parameters, as well as monitoring of drive status variables. Manual pushbuttons can also be wired to the drive in a two or three-wire configuration to control basic functions.

A two-wire control setup provides a run command input and a direction input to the drive. The run command must remain high (on) for the drive to run the motor. The direction command controls forward and reverse motor rotation. Deactivating the run command stops the motor.

With three-wire control of a drive, a stop command is added to the drive control inputs. To activate the drive, the stop command must be high, often through use of a normally closed (NC) pushbutton or an NC relay contact. A momentary run command is all that is needed to activate the drive.

Both two or three-wire drive control methods can be via manual pushbuttons, PLC-activated relay outputs, or PLC discrete signal outputs. Some drives also have programmable functions such as jog, speed change, and acceleration and deceleration control.

Analog signals can also help control drives to deliver speed-control or tension-control functions. Signals take the form of analog 0 to 10 Vdc voltages, analog 0-to-20-mA or 4-to-20-mA current, or potentiometer signals. A two or three-wire discrete control method is still needed to start and stop the drive.

Digital communications between PLCs and VFDs

In addition to discrete and analog inputs, PLCs often control VFDs using digital communications such as Modbus ASCII and Modbus RTU, or via industrial Ethernet protocols specifically created for real-time control. These digital communications can control all drive functions or work in concert with discrete and analog signals. This two-way digital communication often enables all drive commands to be controlled by a PLC, as well as monitoring all drive parameter and reading drive variable, status and fault codes. This can include more than 100 commands, parameters, and status and fault codes.

Serial or Ethernet communication from the PLC can issue speed references, run, direction and jog commands. It can also adjust motor parameters such as voltage and amps and run parameters associated with set acceleration and deceleration times, S curves, and skip frequencies. Other digital parameters include the issuing multi-function input commands and triggering functions just as a discrete input would. Target frequency and current (and many other analog and preset parameters) are also available for control and monitoring using digital communication. Where the PLC communicates with the drive to monitor status and fault codes, it might compare the frequency command to output frequency or the output current to rated current or motor rpm.

The monitoring of drive faults is also enhanced by digital communication. Instead of just a ‘fault present’ discrete signal, the system can register dozens of error codes — including overcurrent, overvoltage, overtemperature, overload, low voltage, and more.

Upfront programming of the drive’s monitoring and control functions (through discrete communication) makes for a more intelligent system. A serial or Ethernet link between the PLC and drive(s) is required; with Ethernet, a hub or a switch is also needed. The ability to configure, control, and monitor the drive from the PLC via digital communications helps futureproof automated systems.

These WEG-CFW300 ac drives from AutomationDirect offer high performance in a compact size, along with a built-in operator interface and a SoftPLC. They eliminate the need to purchase, install, and integrate an external PLC with the drive.

Programming ac drives with built-in PLCs

As mentioned, PLC control of VFDs is well-developed with many configuration and monitoring options. But devices at the machine edges are becoming smarter … and VFDs with built-in PLCs are no exception. These VFDs provide all the precise variable speed-control functions of separate PLC-controlled drives, but in one compact package. Such Smart drives typically have a built-in operator interface panel and a SoftPLC. Via the interface panel, it is possible to control the VFD and view (and adjust) its parameters. A typical keypad toggles between parameter numbers to show position or value. Up and down buttons let operators change the parameter number or its value. Anotehr button lets operators run and stop the drive and reset drive faults. A variety of plug-in option modules are typically available for additional I/O … and to add additional communication protocols.

In an array of applications, smart drives can often control entire machines or systems … helping negate the need to purchase, install, and integrate separate PLCs and operator interfaces.

Some vendors provide free PC-based programming software for the SoftPLC portion of the drive — to let design engineers create custom-tailored control schemes. These then download from the PC to the drive (often via a USB connection). Such software typically includes ladder diagram programming for the creation of function blocks to monitor inputs, operate the drive, and control outputs. Besides controlling the VFD housed in the same package, the SoftPLC can also work to monitor additional components on the plant floor — including other VFDs.

A VFD with a built-in Soft PLC can monitor sensors and run programmed logic to properly convey products.

Driving conveyor, mixer, and other applications

Common applications for smart drives include packaging machines, mixers, kneaders, and dosing pumps. Other applications include the control of fans, exhausts, centrifugal pumps, granulators, palletizers, stirrers, and conveyor belts. Many conveyor or gate applications need to monitor inputs from a few sensors to properly control a VFD as well as an output to trigger a solenoid. Here a carefully selected smart drive having a built-in PLC (meeting full-load amperage, overload, and temperature requirements) can monitor sensors; make programmed decisions; and control field devices.

Jeff Payne is a product manager for the Drives & Motors Group at AutomationDirect. Before joining the company 20 years ago, he managed, designed, programmed, installed, maintained, and repaired a wide variety of automated equipment. He’s worked in the field of industrial automation for nearly 28 years and earned a degree in Industrial Systems Technology and Industrial Automation from Lanier Technical College.

maxon opens new manufacturing facility in Massachusetts

March 21, 2019 By Miles Budimir Leave a Comment

maxon precision motors, a division of maxon motor of Sachsein, Switzerland, has opened a new manufacturing facility in Taunton, MA. The two-story, 59,000 sq. foot facility is located within the Myles Standish Business Park in Taunton at 125 Dever Drive.

Company officials led by Chris Blake, mpm President welcomed state/local officials and invited guests to a grand opening event at the facility the morning of March 19^th which included a ribbon cutting ceremony and tours of the building.

maxon ribbon cutting ceremony. L to R (Louis Ricciardi, Taunton Development Corp., Tom Hoye, Mayor of Taunton, Chris Blake, mpm President, Karl Walter Braun, maxon Shareholder, Eugen Elmiger, maxon CEO)

The new building will provide design engineering and production operations, significantly advancing maxon precision motors presence and capabilities in North America. Its opening is an integral component in an ongoing global growth strategy underway by the privately owned Swiss company, in business since 1961.

maxon motor is a provider of precision dc motors and drive technology with distribution and sales in 40 countries worldwide. maxon’s products include brushed and brushless DC motors, gearheads, sensors/encoders and customized drives. Its highly engineered products are used in a wide range of industries and applications including medical technology, industrial automation, robotics, security and communications, aerospace, automotive, and measurement/testing.

The new facility replaces a former sales/distribution and assembly operation at 101 Waldron Road in Fall River, MA, and will significantly expand maxon precision motors capabilities and employment. USA customers will benefit from closer collaboration that will provide value added opportunities with faster turnaround. Plus, a localized supply chain with domestic vendors will help build stronger customer relationships while reducing lead times.

“Our vision is to be an integral part of maxon’s global growth strategy,” explained Mr. Blake, who heads up the US management team. “With expanded engineering services in place, our customers will enjoy a closer collaboration on design and manufacturing and have a more direct line to our team during concept development, which will include rapid prototyping to better execute customer-specific products.”

For more information, visit www.maxonmotor.com.

Omron to demonstrate advanced solutions for flexible manufacturing, traceability and more at Automate show

March 21, 2019 By Danielle Collins Leave a Comment

Industry-leading automation solutions provider, Omron Automation Americas, will demonstrate a diverse solution portfolio encompassing traceability, flexible manufacturing, human-machine collaboration and more at the upcoming Automate Show in Chicago this April.

Omron Automation Americas, a global leader in end-to-end solutions for industrial automation, will be at the upcoming Automate Show to demonstrate applications for the factory of today and that of the future. Omron’s diverse technologies on display will feature solutions for traceability and flexible manufacturing.

The biennial Automate Show gives attendees the opportunity to see many of the world’s cutting-edge manufacturing technologies in action. Taking place from April 8-11 in Chicago, it provides a key opportunity for Omron to showcase technologies that help manufacturers improve productivity, flexibility, and human-machine interaction.

In booth #8737, Omron will be presenting its Factory Harmony exhibit, a multifaceted display that provides a vision of the manufacturing floor of the future. Each demo in the exhibit is designed to illustrate ways in which machines can collaborate more effectively with humans on the factory floor.

The Factory Harmony exhibit includes a fully integrated vision-guided robotics pick-and-place demo that shows the potential for machines to manage finely detailed work with speed and accuracy as part of a flexible manufacturing system, as well as a traceability demo comprised of laser marking and robotic technologies. Flexibility and traceability are key targets of Omron solutions.

Other robotic solutions on display at Automate include Omron’s TM Series collaborative robot, a flexible solution for human-machine collaboration, and the LD Series mobile robots that move materials flexibly throughout the factory. Both solutions help manufacturers meet growing demands for customization without completely reconfiguring their production lines.

The Omron booth will also feature a demo of its most advanced machine vision technology, as well as its safety product offerings. In total, the Factory Harmony exhibit demonstrates a new standard for human-machine collaboration to help manufacturers enjoy improvements in productivity, efficiency, quality, and worker satisfaction.

Omron Automation

What is nested vector interrupt control (NVIC)?

March 20, 2019 By Danielle Collins Leave a Comment

In a microcontroller, such as those at the heart of industrial motion controllers, interrupts serve as a way to immediately divert the central processing unit from its current task to another, more important task.

An interrupt can be triggered internally from the microcontroller (MCU) or externally, by a peripheral. The interrupt alerts the central processing unit (CPU) to an occurrence such as a time-based event (a specified amount of time has elapsed or a specific time is reached, for example), a change of state, or the start or end of a process.

Interrupts can be triggered internally – from a timer, for example – or externally, from peripherals.

Another method of monitoring a timed event or change of state is referred to as “polling.” With polling, the status of a timer or state change is periodically checked. The downsides of polling are the risk of excessive latency (delay) between the actual change and its detection, the possibility of missing a change altogether, and the increased processing time and power it requires.

With polling, the CPU periodically checks for a change of state. Interrupts automatically notify the CPU when a change of state occurs, ensuring the change is not missed and its detection is not delayed.
Image credit: Renesas Electronics Corporation

When an interrupt occurs, an interrupt signal is generated, which causes the CPU to stop its current operation, save its current state, and begin the processing program — referred to as an interrupt service routine (ISR) or interrupt handler — associated with the interrupt. When the interrupt processing is complete, the CPU restores its previous state and resumes where it left off.

Nested vector interrupt control (NVIC) is a method of prioritizing interrupts, improving the MCU’s performance and reducing interrupt latency. NVIC also provides implementation schemes for handling interrupts that occur when other interrupts are being executed or when the CPU is in the process of restoring its previous state and resuming its suspended process.

The term “nested” refers to the fact that in NVIC, a number of interrupts (up to several hundred in some processors) can be defined, and each interrupt is assigned a priority, with “0” being the highest priority. In addition, the most critical interrupt can be made non-maskable, meaning it cannot be disabled (masked).

One function of NVIC is to ensure that higher priority interrupts are completed before lower-priority interrupts, even if the lower-priority interrupt is triggered first. For example, if a lower-priority interrupt is being registered* or executed and a higher-priority interrupt occurs, the CPU will stop the lower-priority interrupt and process the higher-priority one first.

* A register is a special, dedicated memory circuit within the CPU that can be written and read much more quickly than regular memory. The register is used to store information such as calculation results, CPU execution states, or other critical program information.

Similarly, a handling scheme referred to as “tail-chaining” specifies that if an interrupt is pending while the ISR for another, higher-priority another interrupt completes, the processor will immediately begin the ISR for the next interrupt, without restoring its previous state.

With tail-chaining, if an interrupt is pending as the ISR for another, higher-priority interrupt completes, the processor will immediately begin the ISR for the next interrupt, without restoring its previous state.
Image credit: Arm Limited

The term “vector” in nested vector interrupt control refers to the way in which the CPU finds the program, or ISR, to be executed when an interrupt occurs. Nested vector interrupt control uses a vector table that contains the addresses of the ISRs for each interrupt. When an interrupt is triggered, the processor gets the address from the vector table.

The prioritization and handling schemes of nested vector interrupt control reduce the latency and overhead that interrupts typically introduce and ensure low power consumption, even with high interrupt loading on the controller.

Feature image credit: Arm Limited

New high-speed, compact brushless motors from Portescap

March 19, 2019 By Miles Budimir Leave a Comment

Portescap has expanded its Ultra ECTM range of brushless dc slotless motors with the introduction of the new 35ECS motor. This 2-pole motor offers ultra high speed and power (up to 330 W, max continuous) without compromising on the smooth operation and long life offered by Portescap’s brushless slotless motors.

The new 35ECS motor is available in two lengths: the 35ECS60 and the 35ECS80. The 35ECS60 and 35ECS80 motors feature Portescap’s patented Ultra EC coil technology which provides unparalleled torque and power density with limited core losses over a wide range of working speeds without friction and brush wear. These motors feature a patented high-speed rotor design as well to sustain speeds up to 40,000 rpm. The 35ECS80 is unique and opens new areas for slim/long package with impressive torque capabilities at high speeds, while the 35ECS60 allows high speed capabilities at low voltages. Thanks to its rugged design, the 35ECS can sustain peak torque during 2 sec up to 1.1 Nm (35ECS60) and 2.0 Nm (35ECS80).

The 35ECS motors can be used in a range of applications, including industrial applications, enhancing the life and reliability of a device without compromising on power and machine throughput and saving energy. The new 35ECSs are an ideal choice for applications such as battery-operated hand tools (industrial tightening devices or drills), factory automation equipment (large fans or vacuum pumps), and also for applications with diameter constraints.

The new 35ECS motors feature a laser-welded front flange to ensure the strongest housing to sustain high torque reaction. A temperature probe on the coil head ensures an optimized control of motor performances in heavy duty applications. These motors are offered with hall sensors and a total of six different coils to match speed and voltage requirements. Upon request, Portescap can also provide options for customization including gearboxes, encoders, coil variations and mechanical interface modifications.

For more information, visit www.portescap.com.

What is Space Vector Pulse Width Modulation (SVPWM)?

March 14, 2019 By Danielle Collins Leave a Comment

One common, modern method for controlling three-phase induction motors and permanent magnet synchronous motors (aka BLAC or PMAC motors) is field oriented control, which independently controls the magnetizing and torque-producing components of the stator current. This allows the torque-producing component to be kept orthogonal to the rotor flux, maximizing torque production.

Space vector pulse width modulation (SVPWM) is a technique used in the final step of field oriented control (FOC) to determine the pulse-width modulated signals for the inverter switches in order to generate the desired 3-phase voltages to the motor.

Field oriented control with space vector pulse width modulation.
Image credit: Texas Instruments

The following is a summary of how FOC with SVPWM operates:

1) Measure two of the three motor phase currents and feed them into a Clarke transform to convert them from a three-phase system (i_a, i_b, i_c) to a two-dimensional orthogonal system (i_α, i_β). Note that it’s not necessary to measure all three currents, since the sum of the three must equal unity (0). So the third current must be the negative sum of the first two.

2) Apply a Park transform to convert the two-axis stationary system (i_α, i_β) to a two-axis rotating system (i_q, i_d), where the d axis current is aligned to the rotor flux and the d axis current (the torque-producing component) is orthogonal to the rotor flux.

3) The stator current flux and torque are controlled independently, typically by PI controllers. Voltages to be applied to the motor, V_dand V_q, are determined from the PI controllers.

4) Next, an inverse Park transform converts the two-axis rotating system (V_sqref, V_sdref) back to a two-axis stationary system (V_s_αref, V_s_βref). These are the components of the stator voltage vector and are the inputs for the SVPWM, which generates the 3-phase output voltage to the motor. (Note that the use of SVPWM eliminates the need for an inverse Clarke transform to obtain the three-phase output voltages.)

Field oriented control transforms a three-phase system time-dependent system into a two-coordinate (d and q), time-invariant system. SVPWM is used in the final step to determine the PWM signals to be applied to the motor.
Image credit: Freescale Semiconductor

The details behind SVPWM

Voltage is delivered to the motor by a three-phase inverter with six transistors (two on each leg of the output). Each of the three outputs can be in one of two states (top transistor closed and bottom transistor open, or vice-versa), giving eight (2³) total states for the output. These are referred to as base vectors.

For each leg of the inverter output, either the top transistor will be open and the bottom closed, or vice-versa. Therefore, there are eight total states (2³) for the inverter output.
Image credit: switchcraft.org

The eight base vectors are plotted on a hexagonal star diagram. Each vector makes up a spoke of the star, with 60 degrees phase difference between adjacent vectors. The two vectors (V₀ and V₇) that contain outputs which are either all plus or all minus are referred to as null vectors and are plotted at the center (origin) of the star.

Each base vector makes up one segment of a hexagonal star, with the null vectors (V₀ and V₇) plotted in the center.

The goal of SVPWM is to produce a “mean vector” during the PWM period (T_PWM) that is equal to the desired voltage vector (V_out).

The location of V_out is determined on the star diagram, and the base vectors that constrain that sector (V₁ and V₃, for example), along with one of the null vectors, are used to synthesize the desired voltage. This is done by applying V₁for a specified time (T₁), V₃for a specified time (T₃), and the null vector for the amount of time necessary (T₀) to provide a resultant vector equal to V_out.

The values of T1, T3, and T₀ can be determined with the following equations:

The simulation of V_out can then be expressed as:

Compared to standard field oriented control, using FOC with space vector pulse width modulation enables more efficient use of the DC supply voltage, provides lower harmonic distortion — which improves power factor — and reduces torque ripple.

Dorner Latin America Now Manufacturing at New Facility in Mexico

March 11, 2019 By Danielle Collins Leave a Comment

Dorner’s new manufacturing facility in Guadalajara, Mexico (Dorner Latin America) enables the company to build and deliver belt and flexible chain conveyor systems more quickly and efficiently for customers throughout Latin America.

Dorner is an industry leader in the design, application, manufacturing and integration of precision industrial and sanitary conveyor systems.

The new facility, staffed with experienced employees, is manufacturing Dorner’s popular 2200 Series low profile belt conveyor, which is ideal for assembly, light manufacturing, and other industrial applications. Additionally, the facility is also manufacturing FlexMove flexible chain conveyors, which are designed for pharmaceutical, paper converting, and consumer goods packaging applications. All Dorner conveyors and equipment will be supported through the Guadalajara customer service and engineering teams.

“We have seen tremendous growth in Mexico and Latin America. We’re excited to open a new manufacturing facility and continue expanding our team in Guadalajara so we can provide better and faster support for our customers,” said Dan Nasato, Vice President – International, Dorner.

Dorner – Latin America is located at:

Dorner Latin America, S. de R.L. de C.V.

Carretera a Nogales #5297, Nave 11

Fracc. Parque Industrial Nogales

Zapopan, Jalisco C.P. 45222 México

To contact Dorner – Latin America, call +52.33.30037400 or email: info.latinamerica@dorner.com.

What are pallet conveyors? (Not to be confused with pallet-moving conveyors)

March 8, 2019 By Danielle Collins Leave a Comment

Pallet conveyors transfer discreet products on carriers referred to as “pallets,” typically transported by belt, roller chain, flat-top chain, or for extremely high loads, powered rollers.

For the heaviest loads, in applications such as appliance assembly and automotive manufacturing, pallets are transported by rollers.
Image credit: Bosch Rexroth Corporation

Although they’re typically offered in standard sizes, pallets can be tooled with custom fixtures to locate and secure the product on the pallet.
Image credit: Glide-Line

Pallet sizes are, for the most part, standardized among manufacturers in metric dimensions (240 x 240 mm, for example), although some manufacturers offer pallets in inch or non-standard metric dimensions. In many cases, conveyor pallets are tooled with custom fixtures to locate and secure the product on the pallet. So not only can the pallet be accurately positioned on the conveyor, but the product can be precisely located on the pallet. This makes pallet-based conveyors the ideal solution for high-precision assembly, machining, inspection, and positioning tasks.

Note that the pallets discussed here are different from the pallets used for storing and handling bulk goods, which are often made of wood or plastic. Similarly, some roller- and chain-driven conveyors are marketed as “pallet conveyors,” for the transportation of these wooden or plastic pallets through a factory or warehouse.

Pallets can be transported around corners without changing the pallet orientation.
Image credit: Dorner Mfg. Corp.

Pallet conveyors are suitable for transporting products in two dimensions, but can accommodate small elevation changes. Curved sections — typically from 15 to 180 degrees — allow conveyors to change the direction of transport while maintaining pallet orientation. Conveyor modules referred to as “lift and rotate” units allow the orientation of the pallet to be changed while maintaining the direct of transport. Pallets can also be lifted and precisely located, for positioning at a workstation or inspection area, where pallet conveyors allow access to the workpiece from more than one side. For access to the bottom of the workpiece, pallets can be made with an open center.

The use of pallets to move individual products allows non-synchronous movement, so each product can be transported and routed independently. Because the pallets are precisely machined, they can be accurately positioned and located via sensors, and RFID tags or other data carriers can be attached to each pallet to track and document individual product movements. Pallets can be diverted and merged for offline operations, and accumulation allows products to be buffered, smoothing the flow of downstream operations.

Here, pneumatic cylinders are used to stop and lift the pallet. Precise locating is achieved by pins that mate to bushings on the pallet.
Image credit: mk North America, Inc.

Most pallet conveyors — especially those used in automation applications — are modular, based on standard conveyor sections, legs, and lift/transfer/rotate modules that can be easily reconfigured or expanded as needs change. And because components are standardized, pallet-based conveyors can be configured to meet a wide range of environmental requirements, including cleanroom, dry room, washdown, and ESD-compatible applications.

Feature image credit: Dorner Mfg. Corp.

An apocalypse that wasn’t – The rare earth mineral shortage

March 7, 2019 By Lee Teschler Leave a Comment

Leland Teschler, Executive Editor
lteschler@wtwhmedia.com
On Twitter @ DW_LeeTeschler

Scan the news pages from about eight years ago and you will likely notice a lot of hand-wringing about shortages of “critical materials” crucial for high-tech motors. The materials in question were rare-earth metals used for, among other things, making magnets with a super-high energy density. Back then, China began limiting exports of rare-earth metals. Because that country supplied 97% of the world’s rare earths, the price of neodymium used in brushless motor magnets quadrupled. This price explosion led to the founding of Molycorp Inc., a U.S. mining company with a way of extracting rare earth metals from ore that experts said was innovative.

Today, the price of rare earths has come back down to earth. Recently you could buy a ton of neodymium oxide for about $47,000 whereas the same amount of material in 2011 went for over $250,000. Molycorp entered Chapter 11 bankruptcy a few years ago and its assets were recently liquidated. China still provides about 70% of the world’s rare earth metals. So you might wonder why the price of rare earths crashed, even in the face of a trade tariff war with the main source.
Insights come from a paper by University of Texas public affairs Prof. Eugene Gholz, who advises the DoD on rare earths. Gholz points out that Chinese producers found various ways of getting around the export limits the Chinese government imposed on rare earths. He estimates the Chinese illegally exported as much as 30,000 tons of rare earths annually.

Moreover, some of the applications for rare-earth permanent magnets turned out to be illusory. When the price popped, demand for these magnets fell partly because some manufacturers were able to get by with weaker ones. And materials researchers cranked up efforts to minimize the use of rare earths in magnet alloys.

Even so, the magnetics in motors and electronics accounted for only a small fraction of total rare earth production. At the time of the production bruhaha, cellphones needed a few grams of neodymium and a Toyota Prius used about a kilogram of the stuff. Toyota says it has since reduced its neodymium needs by about 20% per car, though it uses more of the cheaper lanthanum and cerium to do so. Experts predict a surplus of these two materials for many years to come.

Actually, the main application for rare earths back in the days of the bubble was as catalysts in gasoline refining. But you can refine gasoline without rare earths. Gholz reports that some refiners did so at the peak of the 2011 rare-earths price pop, at the expense of a slightly less efficient refining process. The change didn’t do much damage to their financials, he says.

Meanwhile, production of rare earths outside China ramped up. Though Molycorp met an ignominious end, Lynas Corp. in Australia now produces rare earths at a rate of about 22,000 tons annually. Russia and Brazil both put out a few thousand tons each.

The fear back in 2011 was that rare earth metal supplies would go the way of the 1973 oil embargo. But the lesson from the ensuing panic, says Gholz, is that the oil embargo was a special case. Where there’s economic coercion, there’s also an opportunity for introducing competition and a rationale for investing in potential innovations.