Custom sheet metal fabrication

Sheet metal fabrication from China, managed end to end

7DayParts handles custom sheet metal fabrication for engineers and hardware teams outside China. Parts are made in partner shops in China; our team manages each order, checks first articles and inspects critical dimensions before shipping. You send a flat-pattern-ready 3D model and a drawing, and you get one quote covering cutting, forming, welding, hardware and finish.

Typical parts: electronics enclosures and covers, rack and chassis panels, mounting brackets, L- and U-channels, guards, sheet metal enclosure lids, and welded frames. Quantities run from a single prototype to around 1,000 pieces.

Processes: laser cutting and bending, welding, hardware, finishing

• Laser cutting. The flat blank, holes, slots and cutouts are cut from sheet on a fiber laser. Small holes are possible, but a hole diameter of at least the sheet thickness cuts cleanly and keeps its shape.
• Press-brake bending. Flanges are formed with standard V-dies and punches. Bend radius, flange length and bend sequence are set by tooling, so the design rules below matter more than in machining.
• Welding. Seams, corners and frames are welded and, where the drawing calls for it, ground flush. Welding adds heat distortion; flatness on large welded panels should be toleranced realistically.
• Hardware insertion on request. Self-clinching nuts, studs and standoffs (PEM-type) are pressed in after cutting so you get threads in thin sheet without tapping.
• Finishing. Powder coating in RAL colors, anodizing for aluminum, zinc or nickel plating, bead blasting and laser marking. See surface finishes for the full list.

Sheet metal materials

Other grades and gauges can be sourced on request; state the thickness in mm on the drawing rather than a gauge number, since gauge tables differ between steel and aluminum. For machined aluminum grades see aluminum, and for stainless see stainless steel.

Sheet metal design rules

Most sheet metal cost and quality problems come from a handful of features that the press brake cannot form as drawn. These rules of thumb apply to standard tooling; we flag anything outside them in the DFM notes that come with every quote. T = material thickness.

K-factor. The flat pattern depends on where the neutral axis sits in the bend, expressed as the K-factor (typically 0.3–0.5 depending on material, thickness and radius). Your CAD default may not match the shop's tooling, so treat your flat DXF as a reference. We develop the flat pattern from your 3D model and hold the formed dimensions on your drawing, which is what actually matters.

Tolerances. Laser-cut features on a single flat surface hold tightly. Dimensions that run across one or more bends accumulate bend-angle and flat-pattern error, so they are inherently looser than machined dimensions. Put tight tolerances only where parts mate, and dimension from the feature that matters. Our tolerance guide explains how to call them out.

Sheet metal vs CNC machining: which costs less?

For thin-walled parts, sheet metal is almost always cheaper than machining. A bent enclosure starts as a flat blank with little waste; machining the same shape out of a solid block removes most of the material and takes much longer on the machine. Sheet metal also scales well: once the flat pattern and bend program exist, each additional part is fast.

Choose sheet metal when:

• Walls are uniform and between roughly 0.8 and 6 mm thick
• The part is a box, cover, bracket, panel or frame
• Tolerances across bends of a few tenths of a millimeter are acceptable
• You need large parts that would be expensive to machine from billet

Choose CNC milling or turning when:

• The part needs varying wall thickness, pockets, bosses or ribs
• Mating features need ±0.03 mm or tighter across the whole part
• Sealing faces, bearing bores or precision threads are involved
• The part is small and thick, so there is little to bend

Hybrid designs are common: a sheet metal enclosure with a machined heatsink or mounting block, ordered together. If you are not sure which way to go, upload the model and ask; the DFM notes will say which route is cheaper for your quantity. For what drives price either way, read how much CNC machining costs.