Custom Metal Fabrication Offshore: What US Buyers Need to Know

Sheet metal, welding, and stamping account for roughly 35% of all custom manufacturing spend by US industrial companies. Domestic fabrication works for prototypes and rush jobs — but at $85–$150/hr shop rates, production volumes become painful fast. Offshore metal fabrication offers 40–65% cost savings while matching the quality specs most commercial applications demand.

This guide covers what you need to know: which processes translate well offshore, realistic cost benchmarks, how to spec parts for overseas fabrication, and how to avoid the pitfalls that trip up first-time offshore buyers.

Processes That Work Well Offshore

Sheet Metal Fabrication

Laser cutting, CNC punching, bending, forming, and finishing — the bread and butter of offshore metal fab. Vietnam and Chinese shops run the same equipment (Trumpf, Amada, Bystronic) as US fabricators.

For detailed design guidelines, see our sheet metal design tips.

Metal Stamping

Progressive die stamping is where offshore sourcing saves you the most per unit. The economics:

• Progressive die tooling: $5,000–$25,000 offshore vs. $15,000–$80,000 domestic (complexity-dependent)
• Part cost at 100K volume: $0.03–$0.30 offshore vs. $0.08–$0.75 domestic
• Die lead time: 4–8 weeks offshore, 8–16 weeks domestic
• Sweet spot: Annual volumes above 50,000 units. Below that, laser cutting + bending is often more economical.

Stamping tolerances offshore: ±0.05mm on blanked features, ±0.1mm on formed features, ±0.5° on bend angles. Sufficient for most brackets, clips, connectors, and enclosure parts.

Welding and Assembly

Welding is where the labor cost gap really shows. A welded steel chassis that takes 4 hours to fabricate:

• US cost: $340–$600 (welding labor + materials + finishing)
• Vietnam cost: $80–$160 (same quality, AWS D1.1 certified welders available)
• Certifications available: AWS D1.1 (structural steel), D1.2 (aluminum), D1.6 (stainless), D17.1 (aerospace) — all available at qualified Vietnam shops

Robotic welding (MIG, spot) is increasingly available for high-volume applications. Manual TIG welding for stainless and aluminum is a particular strength in Vietnam's manufacturing sector.

Materials: What's Available Offshore

Offshore fabricators work with the same materials you specify domestically. Availability by region:

Steel

• Mild steel (A36, Q235): Universally available. Local mills (Hoa Phat, Formosa Ha Tinh) produce at competitive pricing. Sheet: 0.5–25mm.
• Stainless (304, 316L, 430): Available from POSCO Vietnam, regional distributors. Premium over mild steel: 3–4× (vs 4–5× domestic).
• Spring steel (1074, 1095): Import from Japan/Korea, 2–3 week lead.
• Galvanized / Galvanneal: Locally produced. Hot-dip and electro-galvanized both available.

Aluminum

• 5052-H32: Most common sheet metal aluminum. Excellent formability. Readily available 0.5–6mm.
• 6061-T6: Available in sheet and plate. For CNC machined + fabricated hybrid parts.
• 5083-H116: Marine grade. Available through import channels, 1–2 week lead.

Other Metals

• Copper/Brass: C110, C260, C360 — available for bus bars, connectors, decorative hardware
• Titanium: Available but limited to grade 1/2 sheet. Grade 5 requires import.

Finishing and Surface Treatment

Most post-fabrication finishes are available offshore:

• Powder coating: RAL/Pantone color matching, 50–120μm film thickness. $0.80–$2.50/sq ft.
• Wet painting: Automotive-grade 2K polyurethane available. $1.50–$4.00/sq ft.
• Anodizing: Type II and Type III (hard coat). Color anodizing for aluminum. $0.50–$2.00/sq ft.
• Plating: Zinc, nickel, chrome, zinc-nickel — all available. RoHS/REACH compliant chemistries.
• Passivation: Citric acid (preferred) and nitric acid processes for stainless steel.
• Silk screening / pad printing: For labels, logos, markings. $0.05–$0.30/part.

How to Spec Parts for Offshore Fabrication

The #1 cause of quality issues in offshore fab is ambiguous specifications. Here's how to create drawings that leave no room for interpretation:

Drawing Standards

• Use ASME Y14.5 (or ISO 1101) — Don't mix standards. If your shop reads ASME, spec ASME.
• Call out every tolerance. "General tolerance per ISO 2768-mK" is fine for non-critical features. Critical features get explicit callouts.
• Specify material completely: Not just "stainless steel" — "ASTM A240 Type 304, 2B finish, 1.5mm ± 0.1mm thickness."
• Define weld symbols per AWS A2.4 — Include weld type, size, length, pitch, and inspection requirements.
• Include 3D models: STEP format (AP214/AP242) is universally readable. Supplement with 2D PDF drawings for dimensions and notes.

Critical Spec Checklist

1. Material grade and specification (ASTM/JIS/EN)
2. Sheet thickness with tolerance
3. Bend radii (minimum and preferred)
4. Weld specifications (type, size, inspection level)
5. Surface finish before and after coating
6. Coating specification (type, thickness, color, adhesion test)
7. Hardware insertion (PEM studs, rivet nuts — specify part numbers)
8. Flatness/straightness requirements
9. Edge condition (deburred, rounded, specific break radius)
10. Packaging and labeling requirements

Cost Optimization Strategies

Design for Offshore Manufacturing

• Consolidate parts: Combine multiple sheet metal pieces into fewer weldments. Saves on per-part handling and shipping. An assembly that was 8 parts domestically might become a 3-part welded structure offshore.
• Use standard sheet sizes: Vietnam standard sheets: 1220×2440mm (4×8 ft) and 1500×3000mm. Design parts to nest efficiently on these sizes.
• Standardize bend radii: Use the material thickness as the minimum inside bend radius. This uses standard tooling (no custom punches needed).
• Minimize setups: Design parts that can be cut, bent, and welded without repositioning. Each fixture change adds $5–$15 to part cost.

Volume Strategies

• Batch similar parts: Group parts using the same material and thickness for efficient nesting. A 10-part family cut from 1.5mm SS304 is cheaper per part than 10 separate orders.
• Blanket orders: 6–12 month commitments with scheduled releases reduce per-unit cost by 8–15%.
• Container optimization: A 40ft container holds approximately 22,000 kg. Design packaging to maximize density. Custom steel racks for repeated shipments ($500–$1,500 one-time) save on per-shipment packaging.

Quality Assurance for Offshore Fab

Metal fabrication has more variables than CNC machining. Your QA plan needs to address:

• First Article Inspection (FAI): Full dimensional report (CMM or manual), material cert, weld inspection, coating thickness measurement. Budget $300–$600 per part number.
• In-process inspection: First-off check for each operation (laser, bend, weld, finish). Supplier should provide inspection records with shipment.
• Weld inspection: Visual (100%), dye penetrant (10–20% sample for structural welds), destructive testing (qualification phase only). Specify inspection level in your PO.
• Coating testing: Cross-cut adhesion (ASTM D3359), thickness measurement (ASTM B499), salt spray hours (ASTM B117 — specify required hours: 500hr for indoor, 1000hr+ for outdoor).
• Material traceability: Request mill certs (MTR/MTC) for each heat/lot. Critical for any application requiring PPAP or material documentation.

For a complete quality framework, read our quality control guide.

Common Pitfalls and How to Avoid Them

1. Underspecifying weld requirements — "Weld all around" isn't enough. Specify: MIG or TIG, wire/filler, weld size, visual acceptance criteria (AWS D1.1 Table 6.1 or equivalent).
2. Ignoring thermal distortion — Welded assemblies warp. Specify flatness requirements post-weld and discuss straightening methods upfront.
3. Paint color matching remotely — RAL numbers look different on screens. Send physical color chips. Budget for a paint sample panel before production.
4. Hardware compatibility — PEM, Southco, and other US hardware brands are available offshore, but lead times can be 3–4 weeks. Specify early or approve equivalents.
5. Shipping damage — Sheet metal parts scratch easily. Require PE film on finished surfaces, foam separation between parts, and wooden crating for heavy weldments. The $200 you spend on packaging saves $2,000 in rejected parts.

Getting Started

The best first project for offshore metal fab is a current production part you already have full documentation for. You know the cost, the quality baseline, and the volume — making comparison straightforward.