Breaking the Mold, Pt 2: Segmenting SMCs to Unlock Design Freedom

In Part 1 of this series, we explored how soft magnetic composites (SMCs) are reshaping electric motor design, enabling advanced topologies like axial flux and yokeless axial flux motors. These designs take full advantage of SMCs’ ability to support 3D flux paths, minimize eddy current losses, and allow for complex, near-net shapes. Pushing motor performance forward, however, means confronting real-world constraints, especially in larger or more complex components. That’s where segmentation enters the picture—not just as a manufacturing workaround, but as an enabler of innovation.

Quick Recap: Why SMCs?

SMCs are iron powder particles coated with a high-resistivity insulating layer. This allows them to accomplish the following:

• Guide magnetic flux in three dimensions (unlike 2D laminations)
• Minimize eddy current losses at high frequencies (ideal for 60 Hz to 10 kHz)
• Enable compact, geometrically optimized components
• Reduce material waste and energy usage during manufacturing

As discussed in part 1, SMCs also come with trade-offs that include lower mechanical strength, press size limits, and careful prototyping needs. The ability to navigate these challenges thoughtfully is what separates a part supplier from a true design partner.

When Bigger Ideas Don’t Fit, Enter Segmentation

One major challenge in using SMCs for large components - especially in axial flux - is the size limitation of powder metal compaction tools. Presses typically max out at 16 square inches of planar surface. Segmentation allows engineers to split oversized components into smaller segments that can be individually pressed, optimized, and assembled into a final structure. Actually, the idea of segmenting is not totally new; it was utilized with traditional steel laminations where the motor size resulted in low material utilization. To overcome this cost penalty, the traditional one-piece lamination was replaced by smaller, material-efficient segments that were subsequently assembled.

Why Segment SMC components?

• Size constraints: Essential for producing SMC components too large for traditional compaction
• Easier winding access: Simplifies and improves copper winding placement, reducing losses
• Lower tooling costs: Smaller segments involve less complex tools, lowering upfront capital
• Design freedom: Opens the door for more aggressive geometries in motor topologies

Techniques to Make It Work

When considering segmenting a SMC component, a few engineering design considerations can help you successfully implement this strategy:

• Modular assembly: Use high-performance adhesives or bonding agents to join SMC segments without degrading performance. Welding is avoided to preserve magnetic properties.
• Stacking for scale: Larger motors (i.e., >16 square inches of planar area) can be constructed by stacking pre-bonded modules.
• Hybrid segmentation: Combine segmented SMC parts with electrical steel laminations for strength, cost savings, and thermal performance.

Real Engineering Considerations

As with anything in motor design, segmentation offers powerful advantages—but it also introduces complexity. Here are a few key factors to keep in mind:

Advantages

• Reduced core losses: An inherent advantage of SMC materials
• Sustainable: >95% raw material usage and easier end-of-life recycling
• Scalable: Can be applied through a broad range of motor sizes and performance
• Customizable: Supports creative topologies that are not feasible with stacked laminations

Challenges

• Precise alignment required: This is necessary to maintain optimal magnetic performance.
• Bonding strength: Assembly must maintain structural and magnetic integrity across all segments.
• Manufacturing variability: More segments means more points of potential variability.

As a rule, early collaboration with manufacturers experienced in SMC design for manufacturability is key to mitigating these challenges before they grow costly.

Bringing It All Together

One of Horizon’s most inspiring and challenging programs was the motor shown in the attached figure. This unique electrical device required complex 3D geometry but also necessitated uniform component density throughout the structure. Although the component was less than 16 inches of planar area, the complex 3D shape made insuring uniform high density in the spokes and annular ring nearly impossible.

Our solution was to segment the spokes and annular ring. Through innovative compaction and bonding technology, we created a final solution that met the mechanical, magnetic, and structural requirements of this device, thus creating an ingenious low weight, high efficiency solution. Traditional laminated designs would have required bulky compromises, but segmentation made the impossible possible.

This project is a perfect example of how, when applied strategically, segmentation is not just a constraint workaround but a creative engineering tool.

Looking Ahead: Rethinking the Possible

As electrification demands increase and applications diversify—from ceiling fans to EV drivetrains—engineers are forced to ask: What topology delivers the best performance in the smallest, lightest, and most efficient package while retaining manufacturability? SMCs with segmentation answer that question with component performance, design freedom, and scalability.

So, whether you’re exploring a new motor concept or trying to solve a legacy inefficiency, consider this: What could your motor look like if you weren’t constrained by traditional materials and manufacturing processes?

At Horizon Technology, we’re not just making parts. We’re co-creating the future of electric motors.

Continue the Journey

Download our free guide: AC Electric Motor Design Guide: Soft Magnetic Composites

Have a project in mind? Let’s rethink it together.