Working with Hems

A hem feature is produced when the edge of a sheet metal flange is folded back on itself. SMHEMCREATE simplifies the creation of sheet metal hems. In BricsCAD hems have their own set of properties depending on the type, "flange" and "bend" type of the geometry. Hem features are recognized by the SMCONVERT command and have a special symbol when unfolded with SMUNFOLD.

Create a Hem

  1. Do one of the following:
    • Select several linear edges on the flange.
    • Hover the cursor over a linear edge of the flange.
  2. Do one of the following:
    • Select Create a Closed Hem () tool in the Quad menu.
    • Click the Create a Closed Hem () tool buttons in the Sheet Metal ribbon tab.
    • Choose Create a Closed Hem in the Sheet Metal menu.
    • Type SMHEMCREATE in the Command line.
  3. Hover the cursor to adjust the hem length:
  4. Use the Ctrl widget or Toggle tapering option to flip the adjustment of a hem to the edge:
  5. When finished, press Enter:

Hems and auxiliary features (reliefs and miters) are created.

Modify Hem Parameters

To modify Hem parameters select the feature and use the Mechanical Browser. Different parameters are available, depending on the type of the hem.

Table 1. Hem parameters
Type of hem Available parameters
Closed Radius

Length

Open Radius

Length

Teardrop Radius - change the angle of the hem

Length - change hem length

Round Radius - change the "planar" part of the hem

In the case of any parametric change, the hem type is preserved and the geometry is moved inside, to maintain external dimensions.

Erase a Hem

When a hem feature is erased, BricsCAD intelligently restores the geometry's dimensions and reliefs.

The flange part below has external dimensions equal to 100.

  1. Use the Width option of the SMHEMCREATE command to create a partial hem on a single edge:
  2. Create hems on 2 other edges:
    These operations lead to the appearance of complex relief geometry:
    Note: The external dimensions of the part are preserved.
  3. Select the hem features and delete them.
    Some imperfections are left on the corner relief feature and the imprinted edge:
  4. Delete the corner relief feature and use DMSIMPLIFY to get the original part with original dimensions.

Related commands

The MECHANICALBROWSEROPEN command displays the Mechanical Browser.

The SMDELETE command restores a hard edge between 2 flanges to remove a bend or a junction - removes a flange and all adjacent bends. The adjacent flanges are extended up to a junction configuration and the flange is deleted. Restores geometry removed by the miter.

The SMHEMCREATE command creates one or more hems to a sheet metal part by pulling one or more edges of an existing flange.