Magnetics Business & Technology - September/October 2019 - 22

PRODUCT NEWS

Waelzholz High-Strength Electrical Steel Strip with Precisely Defined Magnetic Properties
Showcased at CWIEME Berlin
manner. "Optimizing the magnetic and mechanical properties is
achieved through the interaction of the individual influencing parameters, taking into account the possibilities of large-scale industrial production," said Zufacher.
Earlier, at a symposium in Salzgitter, Germany in November organized by Volkswagen and others to focus on materials and concepts for vehicles of the future, Norbert Brachthaeuser, head of
materials technology for electrical steel strip at Waelzholz, presented new NO grades for use in electric vehicle drives and the
latest advancements in its Backlack bonding technology.

Waelzholz GmbH & Co. showcased its electrical steel strip grades
with precisely defined magnetic properties at CWIEME held in
Berlin in May, particularly its stress-bearing high-strength and
ultra-high-strength grades for use in high-frequency automotive
drives.
Due to their high engine speeds, electric drive concepts place tremendously high demands on the mechanical strength of the electrical steel strip used, explained Waelzholz staff. For this purpose,
Waelzholz has developed special electrical steel strip grades that
combine high tensile strength and outstanding magnetic properties, the company said. Due to a strength-increasing alloy, Waelzholz's HS grades achieve yield strengths of over 500 MPa, making them especially suitable for use in the manufacture of rotor
stacks exposed to high mechanical stress.

Johannes Zufacher

The Berlin show was the latest in
a series of recent efforts by the
company to highlight its electrical
strip products. In March, at the
33rd Aachen Steel Colloquium,
as part of a series of lectures on
low-Loss electrical steel sheets
for energy-efficient drives, Johannes Zufacher from the company's electrical steel strip materials technology department
spoke on the production of highalloyed steel grade concepts for
use in automotive drives.

Due to their high speeds and the resulting high frequencies in
the magnetic core, new drive concepts place particularly high
demands on electrical steel strip, he explained. As a result, sophisticated manufacturing processes are needed to meet these
requirements. Based on high-silicon alloying, the magnetic and
mechanical properties are adjusted through a combination of cold
rolling and annealing processes with the individual process steps
being carefully coordinated.
The goal is to always achieve the lowest possible core losses
and high yield strengths in order to improve motor efficiency while
manufacturing the material in a process and application-optimized

Magnetics Business & Technology * September/October 2019

The Backlack system is designed to bond lamination stacks for
electric motors without any disturbance to their magnetic flux. It
bonds steel plates made from electrical steel strip without damaging the material unlike conventional bonding processes such as
welding, stamping and riveting which leave contact spots behind.
Using Backlack, no stress or deformity is applied to the material
and. as a result, the key material properties of electrical steel strip
remain fully intact, said Brachthaeuser.
It also prevents frequency buzzing which can be an issue with mechanical bonding methods, he noted. "Our Backlack technology
makes complex stack geometries possible without the need for
follow-up fine-tuning to meet precision requirements. Lamination
stacks bonded using Backlack are compact and waterproof."
Despite the wide variety of potential scenarios for the development of e-mobility, one thing is certain, said Brachthaeuser, the
demand for non-grain-oriented electrical steel strip will continue
to grow in the future. Non-grain-oriented electrical steel strip is
an important performance factor, especially in the motors of electric vehicles, which must withstand high loads. High-quality, thin
electrical steel strip significantly reduces eddy current losses at
high frequencies, thereby making highly efficient, low-loss electric
drive systems possible.
A month earlier, at another presentation, Daniel Dunker with the
materials technology unit at Waelzholz, noted that together with its
customers the company will continue working intensively on current development topics such as fast bonding of electrical steep
strip laminations and the use of increasingly thin layers.
Headquartered in Hagen,
Germany, Waelzholz has
2,400 employees worldwide and annually produces
more than 780,000 metric
tons of cold rolled steel strip
and shaped wire at nine locations in Europe, North
and South America and
Asia.
Waelzholz facilities at Hagen, Germany
For more info, see www.waelzholz.com.

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Magnetics Business & Technology - September/October 2019

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