Design Guidelines: Sheet Metal Fabrication

Last modified: April 7, 2021
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Our basic guidelines for sheet metal fabrication include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.

Size

Maximum Dimensions

SIZE 1,193.8mm x 3,022.6mm
LENGTH 3.048m

Minimum Dimensions

FLAT PART 12.7mm x 12.7mm
FORMED PART 38.1mm x 38.1mm

Tolerances

Single Surface

BENDS +/- 1 degree
OFFSETS +/- 0.304mm
HOLE DIAMETERS +/- 0.127mm
EDGE TO EDGE/HOLE; HOLE TO HOLE +/- 0.127mm
HARDWARE TO EDGE/HOLE +/- 0.254mm
HARDWARE TO HARDWARE +/- 0.381mm
BEND TO EDGE +/- 0.254mm
BEND TO HOLE/HARDWARE/BEND +/- 0.381mm

Multiple Surfaces

FEATURES SEPARATED BY TWO OR MORE BENDS +/- 0.762mm

Materials

  • Aluminum (1)
  • Brass (2)
  • Copper (3)
  • Stainless Steel (4)
  • Steel: CR Non-treated (5)
  • Steel: CR Galvanneal and CR Galvanized (6)

Material Thickness

Because sheet metal parts are manufactured from a single sheet of metal, the part must maintain uniform wall thickness. Sheet metal thickness ranges from 0.024 in. (0.609mm) to 0.250 in. (6.35mm).

GAUGE STEEL NON-ROHS COATED STEEL STAINLESS STEEL ALUMINUM COPPER BRASS
  CRS Galvanneal Galvanized 304-2B 304 #4 316-2B 5052-H32 6061-T6 C101 C110 CDA260
 24 0.6096 0.6096 0.6096 0.6096 0.6096 0.6096
 22 0.762 0.762 0.762 0.635 0.635 0.635
 20 0.9144 0.9144 0.9144 0.9144 0.9144 0.9144 0.8128 0.8128 0.8128 0.8128 0.8128
 19 1.0668 1.0668 1.0668 1.016 1.016
 18 1.1938 1.1938 1.1938 1.2192 1.2192 1.2192 1.016 1.016 1.27 1.27 1.016
 16 1.4986 1.4986 1.4986 1.4986 1.4986 1.4986 1.27 1.27 1.6002 1.6002 1.27
 14 1.8796 1.8796 1.8796 1.8796 1.8796 1.8796 1.6002 1.6002 2.032 1.6002
 13 2.2606 2.2606 2.2606 2.2606 2.2606 2.2606 2.286 2.286
 12 2.6416 2.6416 2.6416 2.6416 2.6416 2.6416 2.032 2.032 2.032
 11 3.0226 3.0226 3.0226 3.0226 3.0226 3.0226 2.286 2.286 3.175 3.175 2.286
 10 3.4036 3.4036 3.4036 3.4036 3.4036 2.54 2.54
 8 4.064 4.064 3.175 3.175 3.175
7 4.5466 4.5466 4.064 4.064
3 6.35 6.35 4.826 4.826
2 6.35 6.35

Because sheet metal parts are manufactured from a single sheet of metal, the part must maintain uniform wall thickness.

Sheet metal thickness ranges from 0.024 in. (0.609mm) to 0.138 in. (3.505mm).

Finishing

We offer welded assemblies, standard mill, edge breaking, and orbital-sanded surface finishes along with a number of additional sheet metal finishing options:

  • Seam, tack, and stitch welding
  •  Hardware insertion and riveting: Standard PEM sheet metal hardware
  • Powder coating: A variety of powder coat paint colors available in textured and non-textured finish, including RAL colors. View our powder coat options here
  • Silk screening (one- and two-color): Colors mixed to closely match most Pantone numbers
  • Assemblies: POP-riveted and welded
  • Plating: Anodize, chromate, zinc, and passivate

Bend Radius

We hold a +/- 1 degree tolerance on all bend angles. We offer a wide range of common bend radii, but our standard bend radius is 0.030 in (0.762mm). This is an industry standard and the most cost-effective. Flange length must be at least 4 times the material thickness.

It is recommended to use the same radii across all bends, and flange length must be at least 4 times the material thickness.

Hems

We form both open and closed hems. The tolerance of a hem is dependent upon the hem’s radius, material thickness, and features near the hem.

We recommend that the minimum inside diameter equals the material thickness, and a hem return length of 6x material thickness.

Offsets

Offsets are used to create Z-shaped profiles in sheet metal parts. We offset height tolerance at +/-0.012 in.  (0.304mm) from top of sheet to top of form and recommend an offset of 0.030 in. (0.762mm).

Additional standard options include: available 0.060 in. (1.524mm), 0.093 in. (2.362mm), 0.125 in. (3.175mm), 0.187 in. (4.749mm), 0.213 in. (5.410mm), 0.250 in. (6.35mm), 0.281 in. (7.137mm), and 0.312 in. (7.924mm).

Holes and Slots

Holes and slots should be a minimum of material thickness in diameter. If material is 0.036 in. (0.914mm) or thinner, the hole should be 0.062 in. (1.574mm) from the material edge; if the material is thicker than 0.036 in. (0.914mm), the hole should be at least 0.125 in. (3.175mm) from the material edge to avoid distortion. If hardware inserts are required, the spacing should be according to the manufacturer’s specifications.

Notches and Tabs

Notches must be at least the material’s thickness or 0.04 in. (1.016mm), whichever is greater, and can be no longer than 5 times its width. Tabs must be at least 2 times the material’s thickness or 0.126 in. (3.200mm), whichever is greater, and can be no longer than 5 times its width.

Countersinks

We offer both machined and formed countersinks—conical holes cut into a manufactured object allowing a screw, nail, or bolt to be inserted flush with the surface.

We recommend the major diameters of countersinks measure between 0.090 in. (2.286mm) and 0.500 in. (12.7mm) using one of the following standard angles: 82°, 90°, 100°, and 120°.

Tolerance for formed countersink major diameter is +/- 0.010 in. (0.254mm).

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