Blog

Dec 05 2022

How the Smallest of Components in your Motor May Have the Largest Impact on its Life Expectancy: Understanding Bearing Basics

When we talk about motor systems, it’s not if the motor will fail, it’s when.

Bearings are one of the main failure modes on an electric motor. High-frequency harmonics induce unbalanced phase voltages and currents in the stator and rotor cores. Add in thermal considerations, and over time, bearing lubricant can’t stand up to those conditions, and the bearing fails. Understanding bearing specifications during the process of motor selection can be a critical element in the effort to optimize the lifetime expectancy of your motor.

Bearing Basics

Before diving into the nuances of bearing selection, it’s important to understand the basic components that make up the structure of bearings and how each element plays a role in performance.

Rolling Elements: Balls and cylinders are the rolling elements in the bearing structure. While they can be made of plastic or ceramic, they’re typically made from high purity chrome alloy steel.
Race: The inner and outer race are mostly made from high purity chrome alloy. The raceway transfers force radially and/or axially depending on orientation. For motor applications, the inner race is rotating with the shaft and the outer race is stationary; rotors are connected to the shaft and rotate at the same speed.
Cage: Made from steel, brass, or polymer, the cage keeps rolling elements separate, so they don’t collide, while allowing them to rotate freely.
Shield / Seal: This combination offers protection against outside debris and keeps grease in. The shield is typically a metal plate while the seal is Nitrile/BUNA-N (NBR) or Fluoro (FKM) rubber.

Overall, bearing configuration depends on the application area. For example, the purpose of the shield / seal configuration is to retain grease and keep out debris, but the consequence is higher bearing loss. In electric motors, that increases the likelihood of seal failure. However, in water-tight environments (e.g., IP55 against water jet), a sealed bearing is mandatory (if there are no external seals), so the engineering team has no choice but to cope with lower motor efficiency due to the bearing loss in that case.

L10 and L10g

At Infinitum, we get a lot of questions about bearings—usually in the form of L10 life. By definition, L10 life refers to the number of hours in service at which 10 percent of bearings will fail due to metal fatigue (i.e., 90 percent reliability). It’s a measure of physical component life, and, by extension, provides insights on maintenance; downtime contributes to loss of revenue and additional service costs.

Grease life, L10g life, acknowledges the complexity of grease lubrication mechanisms by using empirical models as a basis for calculation. High temperature dramatically impacts L10g life. In motor applications, hybrid bearings, with ceramic balls and steel races, run much cooler, so they approximately double L10g life values compared to a steel bearing.

In large motors (i.e., 100 to 500 horsepower and up), L10 life is the more important calculation to consider because there are no pre-packed grease bearings. Regular re-greasing is part of maintenance. For smaller motors, like those produced by Infinitum, L10 grease life is the most important determining factor from a maintenance standpoint because of those pre-packaged grease bearings. Typically, grease will deteriorate faster than the actual component.

That said, these values hold a lot less meaning without context. L10 and L10g life are predominantly based on the speed and orientation of the motor that was used for assessment. When comparing L10 and L10g life values between vendors, make sure you’re comparing them within the same environmental context, or you won’t have an accurate snapshot of performance.

Material Selection

Materials matter when it comes to the physical life of components. Unless otherwise specified, Infinitum motors use steel bearings (balls and race).

However, hybrid bearings (steel race, ceramic balls) balance performance and cost across a variety of motor applications. For instance, customers working in mission-critical applications where there are high temperatures, high speed, or strong electric current (e.g., data centers) tend to prefer hybrid bearings.

Infinitum uses hybrid 6200 series bearings or equivalent. Depending on the vendor, codes may provide more or less information about the bearing, but 6200 series specifications are consistent across the board.

There are certain situations where ceramic balls (i.e., silicon nitride) are better suited because they have stronger insulating protection than a steel balls. However, the price tag on hybrid bearings is 3 to 5 times higher than steel. Choosing to go that route adds additional safety margins to minimize risk, but it comes at a cost. On the other hand, applications with shock or sudden impact, like a monster truck motor, wouldn’t be ideal for ceramic balls because they’re too brittle to stand up to the shock.

Bearings play a critical role in motor design and operation. Understanding their characteristics provides helpful insights that set expectations for overall motor performance. At Infinitum, we look to understand your application and budget to ensure you have the best possible combination of components to keep your motor running. Contact us to discuss your upcoming project.

Nov 22 2022

Why Remanufacturing Electric Motors is a Big Idea

To replace or repair? That’s the question.

In 2021, Deloitte reported that over two billion tons of waste ends up in landfills worldwide, and that number continues to rise. Add consideration for electronic waste, pollution, and the increasing strain on limited natural resources, and the case for sustainable manufacturing processes gets stronger and stronger.

800 million electric motors were sold in 2022, which represents a 10 percent increase from 2021. Today, electric motors consume roughly 50 percent of the world’s energy, a number that’s likely to grow as more industrial applications shift to electric power. With increased demand for electric motors, industrial companies, like Infinitum, are looking for ways to participate in the circular economy and assume greater ownership over end-of-life management through strategies like design for serviceability and remanufacturing.

The Ellen MacArthur Foundation defines a circular economy as one that decouples economic activity from the consumption of finite resources. Recycling and remanufacturing are two of several strategies under the circular economy umbrella that could positively impact lifetime emissions for electric motors:

Correctly Disposing of Equipment

Conceptually, recycling is simply disposing of equipment correctly at the end of its life. It involves waste management, like shredding and melting, to process materials for potential reuse. To maintain as much purity as possible, recyclers separate steel from other materials like copper, aluminum, or magnetic alloys. While it’s better than tossing equipment into a landfill, recycling is still labor intensive, so careful consideration should be applied when selecting it as a circular economy strategy.

Remanufacturing as a Circular Economy Pathway

Recycling levels up end-of-life for motors, but refurbishment and remanufacturing take it a step further by extending the life of the motor. In the remanufacturing process, a product or system is disassembled, and each component goes through an assessment process. Any worn components are replaced with updated equivalents to restore the product’s reliability, while keeping some original components and materials in use longer. This arrangement saves energy and avoids unnecessary waste.

Remanufacturing is commonplace in consumer electronics, and it has been for years. Companies like Apple and Best Buy have robust refurbishment programs, and consumers are buying in. One estimate projects the refurbished computer and laptop market will reach $8 billion USD by 2031, and that doesn’t account for smartphones or other consumer electronics that are eligible for refurbishment.

Remanufacturing is set to skyrocket as industrial companies look to apply this technique to cut waste and save energy in complex, high-tech manufacturing applications. Efforts in this space provide great value to customers because remanufacturing costs are typically lower than out-right replacement, and the process happens with zero effort on their part. At Infinitum, we’re excited to see more and more of our peers taking ownership of their product lifecycles.

Designing for Remanufacture

Designing out waste and limiting emissions creates a strong base for the circular economy. Incorporating elements that support remanufacturing sets our customers up for the greatest possible success. At Infinitum, we’re committed to design and manufacturing techniques that support the circular economy from the start:

Modular Design: Our approach allows us to meet application and output requirements by incrementally adding or removing stator panels and/or motor modules. By design, Infinitum motors are more easily customized, serviced, and disassembled for refurbishment or remanufacturing.
Materials Selection: By intentionally designing all aspects of our motors for lighter weight and lower operating noise (e.g., eliminating steel core and copper windings), we use fewer raw materials and precious resources, lessening demand on the environment and the supply chain.
Shipping Practices: We reduce our transportation footprint through localized sourcing and production, but it’s not always about how you ship. What you ship matters too. Infinitum motors produce all the power in half the weight and size of a conventional motor. Smaller footprint and weight also contribute to reducing emissions in the shipping process.

By committing to emerging standards and implementing designs that support the circular economy, we can encourage the industry to be better stewards of our finite natural resources. By working with Infinitum, customers have access to state-of-the-art motors, but they also gain a sustainability partner for a lifetime, literally.

Oct 25 2022

Two Distinct Realms for Electric Motor Reliability Optimization

Regardless of application, technical system performance and support costs depend on a motor’s ability to stand up to its environment. In a well-designed motor, reliability is essential. True, intrinsic reliability results from efforts in two distinct realms: motor architecture and predictive analytics.

From the motor architecture perspective, opportunities for reliability optimization appear in each major component of an electric motor. Condition of stator windings, sliding components, and bearings—the primary failure mechanism of an electric motor—all impact a motor’s lifespan:

Stator Windings: The iron core and copper windings in a traditional motor have different thermal expansion coefficients from one another. By nature, they expand at different rates as motor temperature changes, causing cracks in the winding insulation. Infinitum’s approach to this problem involves a PCB stator with layers of copper and glass-epoxy laminate. With less a smaller discrepancy in thermal expansion coefficient, temperature changes cause uniform contraction and expansion that prevents thermal cracks.
Bearings: Heat is a primary issue to contend with because it degrades bearing grease. System design should focus on keeping bearings cool and properly loaded. Exceeding a motor’s operational specifications shortens its life by adding unnecessary stress on the bearings. Early in development, Infinitum employs heat sink optimization and other thermal management techniques to achieve cooler operating temperatures for the whole motor.

Infinitum motors come standard with steel bearings (balls and race), but hybrid ceramic bearings (steel race, ceramic balls) are available upon request. All Infinitum motors have an L10 bearing life of 50,000 hours for all orientations.

For more information on motor architecture and predictive analytics in electric motor design and manufacturing, check out our white paper “Designing Electric Motors for Intrinsic Reliability” where we’ll cover:

Areas of an electric motor that offer the greatest opportunities for design optimization
How analytics can help mechanical engineers apply precision improvements for greater reliability

Jun 14 2022

PCB Production Improvements for a Greener Future

Raising the bar on motor technology also means making something that’s better for the planet.

At Infinitum, we’ve replaced the iron core and copper windings found in conventional motors with a unique printed circuit board (PCB) stator. By etching copper coils directly onto the PCB stator, we reduce overall copper use by two-thirds.

The slim profile of the PCB stator reduces the volume of the motor and the material needed to produce the housing, resulting in a motor package that is half the size and weight of conventional motors. Infinitum motors also include an integrated variable frequency drive (VFD) to provide precise control of speed and torque.

Placement of the PCB Stator

In an axial flux motor like Infinitum’s, magnetic flux travels parallel to the motor shaft (i.e., in the axial direction) rather than traveling perpendicular to the motor shaft, as expected in a radial flux motor. Infinium motors orient the stator parallel to rotor discs, and the stator is sandwiched between the rotors, as seen in Figure 1. As current passes through the copper wire embedded in the PCB stator, it generates an electromagnetic field that interacts with the magnetic fields surrounding the rotor magnets to generate torque and rotation.

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Description automatically generated — *Figure 1: An Infinitum motor deconstructed to show internal components; the PCB stator is packaged with the front and back rotors*

These PCB stators are built using well established manufacturing processes. Since the early 1980s, a growing number of environmental restrictions and regulations have set out to minimize the environmental impact of PCB manufacturing, and we’re pleased to see a growing number of our industry partners taking steps towards greener fabrication.

Greening Up PCB Manufacturing

The PCB stator manufacturing process parallels the traditional PCB manufacturing process. A layout is printed on copper clad laminates, and the etching process removes excess copper to reveal traces and pads. The PCB layer stack is formed by laminating the board materials at high temperatures. Then, holes are drilled for mounting, and pin holes and vias are plated before coating with a solder mask or other finish. From there, the PCB moves on to reliability and performance testing.

Traditional methods of PCB manufacturing rely on energy-intensive processes with high emissions. These processes involve copper, resins, glass fiber, and a lot of water. To make matters worse, at the end of their usable life, most PCBs become waste products; especially when improperly handled, waste removal processes can exacerbate environmental impact. For example, retrieving copper and other metals from PCBs through incineration releases toxic gasses, and using acid to remove metals results in acidified wastewater.

Today, national and international regulations put pressure on PCB manufacturers to do better. Many manufacturers are beginning to use renewable energy sources in their PCB production facilities, wherever feasible.

Since the establishment of the U.S. Clean Air and Clean Water Acts (CAA/CWA), the Resource Conservation and Recovery Act (RCRA), and the U.S. Environmental Protection Agency, PCB manufacturing processes, materials, and waste treatment methods have evolved continuously.

Regulations have replaced:

Solvent development and cleaning chemistries
High volatile organic compound (VOC) emission chemistries and inks
Lead in plating resists and laminate materials
Ozone depleting ingredients

Many PCB manufacturing facilities have implemented zero-discharge systems that treat rinses to prepare them for reuse or repurpose, avoiding chemical discharge. They’re also making an effort to reclaim copper etching, minimize carbon dioxide emissions, improve panel utilization, see Figure 2, and recycle precious metals once a PCB reaches end of life.

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Description automatically generated — *Figure 2: Comparing panel utilization to relative cost of PCB manufacturing; minimizing waste could result in over 50% cost reduction*

In addition, Infinitum is making a pledge to reuse PCB stators in remanufactured motors. In testing of our PCB stators, we’ve found that this technology is highly durable. Rather than allow our stators, and other motor components, to end up in landfills, we’re committed to finding ways to reuse them to produce remanufactured motors for the next generation (and the next).

As science continues to advance, the EPA and other regulatory bodies will continue to refine their requirements for manufacturers, and with more interest and economic incentive associated with green PCB manufacturing, best practices will continue to proliferate.

We are staying focused on our environmental impact every step of the way. For more information about Infinitum and our approach to sustainability, contact us.

May 10 2022

Applying Next-Gen Motor Performance and Efficiency to Pump Applications

As part of our ongoing efforts to raise the bar for sustainability, Infinitum is extending next-generation motor performance and efficiency to pump applications. With built-in Variable Frequency Drives (VFD) and optional IoT monitoring capabilities, you’ll find Infinitum motor systems in applications from commercial HVAC, water / wastewater, agriculture, food and beverage, and beyond. Want to know what you can expect from an Infinitum motor system? Read on:

Variable Frequency Drives for Better Pump Performance

When an AC motor is first energized to power a pump, it’s susceptible to a large electrical current flow that exceeds the steady-state current value (i.e., in-rush current). Some motor designs address this issue with a soft starter, like a reduced voltage soft starter (RVSS). VFDs control the speed of the motor by producing their own alternating current (AC), ultimately controlling the AC frequency supplied to the motor. With influence over the acceleration and deceleration, a VFD can minimize mechanical stress on the pump system and address common concerns associated with soft starters, such as excessive motor slip, motor heating, and in-rush currents.

At Infinitum, we integrate the motor and the VFD into one modular package. This saves the OEMs, integrators, and end-users who utilize traditional VFDs from having to run wire and install a remote VFD. In addition, our integrated system allows the motor to start with no concerns of current surges when power is applied. Lastly, our VFDs are designed to operate with a maximum THD of 40% on the input side.

Less Noise (and Fewer Maintenance Concerns)

Noise and other mechanical indicators can signal unusual conditions or system inefficiencies that require maintenance. Noise could be caused by any number of factors including abnormal load, incorrect mounting, or brinelling.

From our topology and fundamental technology, Infinitum motors were designed for noise reduction. We designed a synchronous, axial flux, permanent magnet (PM) motor to remove core losses and eddy current loss in the rotor. The absence of magnetic forces between the rotor and the stator means no cogging torque, less vibration, and lower noise.

Smaller Size and Footprint

For small manufacturing or processing facilities, an Infinitum motor system integrated with a pump can free up valuable facilities space by taking a typical packaged pump skid solution and reducing its footprint by 50%. For example, microbreweries are a mainstay in communities across the country—serving as a spot for locals to try new brews and spend time with friends and family. With a VFD mounted directly to the slim profile of our motor, Infinitum offers significant space savings and requires less wiring compared to conventional motor + VFD installations for pump systems. This solution presents cost savings and passes a more manageable system over to integrators and pump OEMs looking for solutions for smaller facilities.

Better Performance in Terms of Efficiency and Reliability

Through a combination of regulation and innovation, motors are continuing to improve in efficiency and energy savings. Some variable speed induction motors are approved for levels exceeding “premium” qualifications (i.e., IE4 and IE5 standards).

Infinitum motors meet IE4 and IE5 efficiency standards, and our VFD delivers up to 98% efficiency. Especially at partial loads, our efficiency curve is flatter for longer compared to AC induction systems. That endurance can help pump OEMs achieve and maintain energy requirements and maximize wire-to-water efficiency. Moreover, Infinitum motor and VFD systems are ETL certified. And as it stands, we are implementing NEMA-standard drive-end bearings and matching that larger specification on our non-drive-end for optimum durability. Pairing this with our PCB stator technology, our solution has proven to be 10x more reliable than iron-core, copper-wound stator machines.

Controllability

Our integrated VFD comes standard with MODBUS control capabilities that can be used to relay information on our motor’s speed and power back to a system controller. This data can be used to determine a pump’s pressure and flow and allow the system to adjust performance as needed. With this capability, mechanical features such as control valves, flow meters, and pressure gauges can be eliminated from the system—saving installation costs and further improving operational efficiencies. Our VFDs can also transmit temperature and vibration readings, so facilities managers and operators have more actionable insights for maintenance.

At Infinitum, we believe in impactful innovation, and we’re tapping into our team’s decades of motor expertise to do just that. Application-focused research and development led us to explore ways to optimize our motor solution to address specific pump OEM concerns such as minimizing shaft end play and mounting compatibility.