Quick Answer

Professional sheet metal fabrication follows six stages: (1) CAD design with flat pattern development, (2) material selection and coil/shearing, (3) cutting via fiber laser or CNC punch press, (4) forming on CNC press brakes with precision backgauging, (5) welding and assembly using TIG/MIG/spot welding, and (6) surface finishing including deburring, grinding, and coating.

Stage 1: Design and Engineering

The process begins with a 3D CAD model that is converted into flat patterns by the CAM software. The engineer calculates bend allowances, determines the bending sequence, and nests parts on standard sheet sizes to minimize material waste. DFM reviews identify potential forming issues, springback compensation, and optimal hole-to-bend distances (minimum 2x material thickness + bend radius).

Stage 2: Cutting

Fiber laser cutting is the most common cutting method. A 3-6 kW fiber laser cuts steel up to 25mm, stainless up to 12mm, and aluminum up to 10mm with kerf widths of 0.1-0.3mm. CNC punch presses are used for high-volume runs with repetitive hole patterns. Waterjet cutting is used for thick plates and materials sensitive to heat.

Stage 3: Bending and Forming

CNC press brakes with backgauging systems precisely position the part and control bend angle. Modern press brakes with 7-axis backgauges and crowning compensation achieve bend angle accuracy of ±0.5 degrees. The bending sequence is programmed to avoid collisions and ensure consistent results across the production run.

Stage 4: Welding and Assembly

Welding processes include TIG (for thin stainless and aluminum), MIG (for thicker steel), and spot welding (for high-volume assemblies). Welding fixtures ensure consistent alignment. Post-weld grinding and blending create smooth joints. Quality inspection includes weld gauge verification and dye penetrant testing for critical applications.

Why Choose SOMI Custom Parts

SOMI Custom Parts operates a complete sheet metal fabrication facility with fiber laser cutting, CNC press brakes, and certified TIG/MIG welding. We manage all six stages in-house, eliminating the quality and logistics risks of coordinating multiple subcontractors. Our engineers provide flat pattern optimization to maximize material utilization, and our quality team inspects every part at each stage of production.

Case Study

A telecom equipment company needed 2,000 stainless steel equipment enclosures with complex cutouts, precision-bent flanges, and TIG-welded seams with a uniform #4 brush finish. SOMI's fab shop laser-cut all parts from 16-gauge 304 stainless, programmed a 7-stage bending sequence for the press brake, and TIG-welded the assemblies on custom fixtures. The entire order was completed in 5 weeks with 98.5% first-pass yield.

Industry Data

According to the Fabricators and Manufacturers Association, a well-equipped sheet metal fabrication shop can produce a simple enclosure from flat material to finished part in 15-30 minutes of labor. Fiber laser cutting has become the dominant cutting technology, accounting for 65% of all sheet metal cutting, up from 35% in 2020 (FMA, 2025).

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