MagSim Knowledge · Toroid Core Basics

Toroid Core CAD Model

Drawing a clean 3D model from toroid core parameters is the easy part. A manufacturable CAD model – with realistic wall thickness, moldable geometry and an exportable STEP file – additionally needs CAD software and design know-how. What to watch out for, and how MagSim automates it, is what this article covers.

Why "some 3D model" isn't enough

A toroid core is rarely used bare – usually a housing or potting compound is added. As soon as a real part is meant to be manufactured from it (e.g. via injection molding), mechanical design rules apply that a purely geometric model doesn't satisfy automatically:

1.5–2.5 mmTypical wall thickness guideline for standard plastics – too thin causes incomplete filling, too thick causes warping and longer cycle times.
≤ 50–60 %Recommended rib thickness relative to the adjacent wall, to avoid sink marks.
uniformWall thickness should stay as constant as possible across the part – important for cooling, demolding and achievable tolerances.

What a toroid core CAD model additionally needs

Beyond the pure core dimensions (outer diameter, inner diameter, height), a housing adds further geometric quantities that must not scale linearly with core size: the radial and axial gap between core and housing wall, the housing wall thickness itself, and the resulting outer contour. A small toroid core and a large one need different but consistent values here – not a fixed constant.

How MagSim handles this for you

For every housing material, MagSim stores a linear coefficient model instead of a fixed wall thickness – so the housing geometry scales correctly with core size. Radial and axial housing gap are tracked separately. The result is exported directly as a STEP file, without you having to operate FreeCAD or any other CAD program yourself.

What format actually matters at the end

For handing a design off to a manufacturer or another CAD program, a vendor-neutral, exchangeable format is what counts. MagSim provides:

STEP – neutral 3D data exchange
FCStd – editable FreeCAD source file (internal/admin)
PDF – matching technical drawing

Design your own toroid core now

Choose geometry and housing material – MagSim automatically generates a manufacturable 3D model including STEP export.

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Frequently asked questions

What software do I need to open a STEP file?

Any common CAD program (FreeCAD, SolidWorks, Fusion 360, Inventor, and others) can open STEP files – the format exists specifically as a neutral exchange standard.

Is a simple 3D sketch enough for manufacturing?

No. Without accounting for wall thickness, draft angles and tolerances, a model can be visualized but not produced without rework.

Can I still edit the generated model afterwards?

Yes – the editable FreeCAD source file (FCStd) can be requested from the admin via the contact page.