Designing sheet metal parts

Most cost and delay in a sheet metal part is decided at the design stage. These rules keep your part simple to cut, form and weld, and they are what our design and engineering team checks first when you send us a model.

1. Keep one thickness

A formed part is made from one sheet, so every wall is the same thickness. If one face needs to be stiffer, add a flange, a rib or a second part welded on, rather than a thicker wall.

2. Use one bend radius

One inside radius for every bend means one tool set-up and a faster, cheaper part. Use at least the minimum radius for your material; see the bend radius and flange chart.

3. Make flanges long enough

A flange that is too short cannot be held across the die. Make every flange at least 4 times the thickness plus the inside radius.

4. Keep holes away from bends and edges

Holes too close to a bend stretch out of round when it is formed. Keep holes at least 2.5 times the thickness plus the bend radius from a bend and 2 times the thickness from an edge, and add a bend relief where a bend meets an edge.

5. Dimension from one datum

Tolerances add up across every bend. Dimension the features that matter, such as hole patterns that mate with another part, from one datum, and tolerate only what the part needs. Tight tolerances everywhere cost more and rarely make a better part.

6. Choose hardware early

Threaded inserts, studs and nuts pressed into the sheet are cheaper than welded nuts or tapped holes in thin material. Name the hardware on your drawing, or ask us to suggest it.

7. Plan the finish

Powder coating adds thickness and needs a hang point; anodizing changes the size of aluminum parts slightly; welds on stainless steel are passivated. Tell us the finish at the start so it is designed in, not worked around.

What to send us

A 3D model in STEP or your native CAD format is best, because we can unfold it directly. A flat pattern DXF and a PDF drawing with the bends, thickness, material, finish and critical tolerances works too. Only have a sketch or an old part? We can model it for you. See starting a project.