Sheet Metal Features in BricsCAD Mechanical Explained

Quick answer: Features are smart groups of faces in a 3D part, each maintaining a specific spatial and parametric relationship between its faces and adjacent faces, embedding design intent directly into the model. They’re created automatically by whichever geometric operation you apply.

Flange

The main sheet metal feature: two parallel planar faces facing each other, with solid volume between them, at a distance far smaller than their linear size, equal to the material thickness. Modifying the model always maintains that distance relationship automatically. Faces adjacent to a flange’s faces that don’t belong to a bend are called thickness faces, always perpendicular to the flange faces themselves.

Created by SMFLANGEBASE, SMEXTRUDE, SMLOFT, SMFLANGEEDGE, SMFLANGEBEND, and SMCONVERT, confirming exactly the commands covered on this hub’s Sheet Metal Commands and Toolbars page.

With FEATURECOLORS on, display color distinguishes a flange’s reference face from its opposite side, confirming the exact practical use of that variable from the Commands and Toolbars page. Parametric modifications (a thickness change, for example) avoid moving reference faces where possible. SMFLIP swaps a flange’s sides so the reference faces sit on the other geometric side, optionally shifting the flange by the part’s thickness.

Bend

Connects two flanges: two coaxial cylindrical faces, always tangent to the adjacent planar flange faces. Created by SMFLANGEBASE, SMEXTRUDE, SMFLANGEEDGE, SMFLANGEBEND, and SMCONVERT.

Zero Bend

A design concept for a bend whose geometry has a cylindrical face on the external side with a radius equal to the material thickness, and an edge instead of an internal face, effectively a zero-radius bend used for design purposes. SMUNFOLD supports these, generating dimensions as though they were regular bends with a radius equal to the thickness.

Wrong Bend

Recognized by SMCONVERT, reflecting an assumption about the user’s design intent. Like regular bends, wrong bends connect flanges, but their faces can be non-coaxial or non-tangent with adjacent flange faces, preventing them from functioning as proper bend features. Before unfolding the part, repair them with SMREPAIR, or remove them with SMDELETE and recreate with SMBENDCREATE.

Lofted Bend

Two ruled surfaces (a surface swept by a moving straight line, cylinders, cones, and helicoids are all examples) facing each other, offset by material thickness, with solid volume between them, created by thickening ruled surfaces. A lofted bend can connect one or two flanges, or stand alone with no flanges at all, and can even be adjacent to regular bends in certain combinations.

Created by SMLOFT and SMCONVERT.

Bend Relief

A group of faces forming a technological cut between two differently-sized flanges connected by a bend, maintaining the distance between the cut’s two opposite faces. Created by SMFLANGEEDGE, SMBENDCREATE, and SMRELIEFCREATE.

Corner Relief

A group of faces forming a cut at a corner where three or more flanges meet, preventing unwanted material deformation during bending, and maintaining that cut’s form and size. Created by SMFLANGEEDGE, SMBENDCREATE, and SMRELIEFCREATE.

Junction and T-Junction

A junction consists of two thickness faces of adjacent flanges not connected by a bend, either symmetric or overlapping, maintaining a minimal distance called the junction gap. A T-junction consists of a single flange’s thickness face positioned near another flange’s face, usually a precursor to creating a T-tab.

Junctions are created by SMFLANGEEDGE, SMJUNCTIONCREATE, and SMFLANGECONNECT; T-junctions by SMJUNCTIONCREATE and SMFLANGECONNECT.

Miter Feature

A split between coplanar flanges, created by SMFLANGEEDGE and SMSPLIT, maintaining a defined miter gap.

Form and Bead Features

Form and bead features cover a wide range of shapes produced by punching and wheeling, with two representations: the 3D geometry itself, and a 2D symbol in the unfolded drawing. For imported geometry, that symbol projects from the form feature’s 3D faces; for one inserted or replaced from the Form Feature Library, the symbol comes directly from the library file instead. A bead feature specifically represents the imprint a wheel leaves on a flange as it follows an arbitrary trajectory.

Created by BMINSERT, SMBEAD, and SMCONVERT.

Tab and T-Tab

Both connect two flanges, restricting their mutual displacement. Created by SMTABCREATE.

Bevel

Chamfers on a part’s thickness faces, defined by both sloped and orthogonal faces. A bevel must belong strictly to a single flange and can’t be adjacent to a bend feature. SMCONVERT can recognize or erase them, and SMUNFOLD supports them.

Frequently Asked Questions

What’s the practical difference between a regular bend and a lofted bend? Regular bends use purely cylindrical surfaces and unfold exactly; lofted bends can use cylindrical, conical, or spline surfaces and generally unfold approximately (though cylindrical and conical lofted bends can unfold exactly too).

What should I do if SMCONVERT flags a bend as a “wrong bend”? Repair it with SMREPAIR, or remove it with SMDELETE and recreate it properly with SMBENDCREATE, before attempting to unfold the part.

What does FEATURECOLORS actually let me see on a flange? Which face is the reference face versus its opposite side, shown through distinct display colors.

Can a bevel feature span across a bend into an adjacent flange? No, a bevel must belong strictly to a single flange and can’t be adjacent to a bend feature.