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Synchronous versus Asynchronous drum motors

Why Synchronous Drum Motors Are the Smarter Long-Term Choice for Food-Grade Conveyor Systems

In the food industry, every component must contribute to hygiene, efficiency, and long-term reliability. One component that often goes unnoticed but plays a crucial role in both safety and energy use is the drum motor.
Asynchronous motors have long been the default choice. They are familiar and the known choice for conveyor applications. But they also come with several challenges, particularly in food-grade environments where oil leaks, energy waste, and limited speed control create recurring problems.
Synchronous drum motors offer a smarter alternative. Their design enhances hygiene, reduces operating costs, and delivers improved performance across the board. In this article, we explain why the switch makes sense and how the investment pays off faster than most expect.

Written by Mathias K. Sørensen, Global Sales Manager, NGI DriveTech

”In food processing, you can’t afford compromises on hygiene, energy use, or uptime. That’s why more companies are switching to synchronous drum motors — not just for better performance, but because the numbers back it up."

Mathias K. Sørensen,Global Sales Manager, NGI DriveTech

No Oil, No Risk of Contamination

Asynchronous motors rely on oil for cooling. This introduces a risk that’s hard to ignore. Over time, seals can wear out or belt tension can push the motor past its design limits. When oil leaks occur, they often go unnoticed until there’s already been damage, or worse, contamination inside the production zone.
NGI’s synchronous drum motors are completely oil-free. Without oil, there’s no chance of leaks, no seals that require regular checks, and no risk of oil entering your food zone. This significantly reduces food safety risks and simplifies compliance with HACCP and other hygiene standards.

High Efficiency Backed by Data

One of the most compelling reasons to switch is energy efficiency. NGI’s synchronous motors convert up to 95% of electrical input into mechanical output. By contrast, asynchronous motors suffer from substantial internal energy losses caused by iron, copper, and mechanical friction.


The impact of this difference is real. In one case, a food processor saved over €500 per motor per year in electricity alone. With dozens of motors in use, the cost savings added up quickly.

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Constant Torque Across All Speeds

Asynchronous motors lose torque at lower speeds, making them difficult to use in variable-speed processes unless oversized. This can lead to unnecessary energy consumption and a more complex parts inventory.


NGI’s synchronous motors maintain full torque across a wide speed range. Whether you’re running high-speed packaging lines or delicate product handling at slower speeds, one motor can handle both. This improves flexibility and reduces the number of motor variants you need to keep in stock.
In one installation, just three synchronous motor types replaced over several asynchronous models, helping the customer simplify inventory and reduce maintenance complexity. Read the Marel case story here


Torque-speed curve comparisons confirm the advantage. NGI synchronous motors offer a flat torque curve from 10% to 100% of rated speed, which is ideal for food lines with start/stop operation or process variability.

Lower Operating Temperatures Extend Lifespan

Synchronous motors run cooler because they are more efficient. There’s less heat loss inside the motor, and no need for oil to assist with cooling. This has a direct effect on the lifespan.


During performance testing, our motors consistently operate below 40°C at full load. Lower temperatures reduce stress on insulation and bearings, which helps extend the mean time between failures (MTBF). This means fewer breakdowns, fewer emergency repairs, and longer service intervals.

Designed for Hygiene from the Ground Up

All NGI synchronous motors are IP69K rated, meaning they can withstand high-pressure, high-temperature washdowns. But the design goes beyond IP ratings.
The motor surfaces are smooth and self-draining. There are no exposed bolts or crevices where bacteria can collect. All materials are compatible with FDA-approved cleaning agents and designed in line with EHEDG guidelines for hygienic processing equipment.
This makes them ideal for meat, dairy, bakery, and other food environments where hygiene is critical, and every washdown needs to be fast and effective.

 

Easy Installation and Retrofit Options

Our motors are designed to fit into the same footprint as many standard asynchronous drum motors. This makes retrofitting simple. The external dimensions, shaft geometries, and cable routing options are all designed to support quick replacement.
We provide full technical drawings and wiring diagrams to ensure compatibility. In most cases, you won’t need to modify your conveyor design to upgrade to synchronous motors.

 

Compatible with Standard VFDs

Synchronous motors require a variable frequency drive (VFD) for speed control. Our motors support both open-loop and closed-loop vector control, depending on your application needs.
Most industrial VFDs on the market are compatible, and we offer guidance to help you select and configure the right one. Once installed, the system provides smooth speed transitions, stable torque output, and precise control over acceleration and deceleration.

 

Pricing and ROI – An Investment That Pays for Itself

We often hear the question: "Aren’t synchronous motors more expensive?" The answer is yes, at the point of purchase. But that’s only part of the story.
When you calculate total cost of ownership, the numbers speak for themselves. Thanks to energy savings, no oil-related maintenance, longer service life, and fewer unplanned stoppages, most customers see a return on investment within 12 months.

To make this easier to evaluate, NGI provides an ROI calculator specifically for drum motors. It allows you to input your current energy costs, motor usage, and maintenance figures to see how quickly the upgrade will pay off.

Built for the Future of Food Processing

Synchronous drum motors offer more than just a technical improvement. They support cleaner production, lower environmental impact, and greater operational control.


If you're planning a new installation or considering a retrofit, NGI’s DriveTech range is designed to help you achieve higher performance without compromising on hygiene or reliability.

Need help finding the right motor or calculating the return on investment (ROI) for your application?

Get in touch with us directly. We're here to support your evaluation and help you move forward with confidence.

Mathias K. Sørensen, Global Sales Manager  DriveTech, NGI

Learn more about the author, Mathias K. Sørensen: 

I have nearly 10 years of experience in the food industry, with a background in production line maintenance, optimization, and hygienic equipment. My career began as a Maintenance Manager at a fish processing facility, where I oversaw site-wide maintenance and gained hands-on experience with a wide range of production machinery.

For the past four years, I’ve been part of the NGI team, working closely with customers to identify the right solutions for their applications. Whether supporting machine builders or collaborating with technical teams at food producers, I focus on ensuring the final installation lives up to both performance and hygiene expectations. My goal is always to deliver solutions that work in practice, not just on paper.

 

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Mathias K. Sørensen
Mathias K. Sørensen
Global Sales Manager

DriveTech Drum Motors

+45 38 41 75 29

+45 20 98 60 14

mks|ngi-global.com

Matias Holch Christensen
Matias Holch Christensen
Area Sales Manager

DriveTech Drum Motors

+45 40 25 95 50

mhc|ngi-global.com