Use this page as a checklist for production routing
This page takes the manufacturing process and turns it into an RFQ checklist. It is meant for buyers comparing quotes, not readers looking for a basic definition.
This page has been separated from the broader process article so Google and buyers can see the job of this article clearly. The useful question here is not “can someone make metal parts?” It is: what should a buyer check before sending drawings, approving a quote or moving into production?
- Confirm drawing review and DFM comments before production.
- Lock material purchase against the approved revision.
- Check cut quality before bending hides access.
- Inspect after welding and before finishing.
- Verify finish, packing and shipping documents before release.
| 1 | Confirm drawing review and DFM comments before production. |
| 2 | Lock material purchase against the approved revision. |
| 3 | Check cut quality before bending hides access. |
| 4 | Inspect after welding and before finishing. |
| 5 | Verify finish, packing and shipping documents before release. |
Drawing to delivery
The sheet metal fabrication process is a controlled sequence that turns a drawing into a finished enclosure, cabinet, bracket or welded assembly. For OEM buyers, the important question is not only which machines a supplier owns, but how drawing review, material control, forming, joining, finishing and inspection connect as one repeatable workflow.
This guide reflects the workflow MSTFAB uses for custom sheet metal enclosures and OEM parts at its Guangzhou facility. Actual tolerances and process choices depend on material, thickness, part geometry, finish and assembly requirements. Buyers should confirm critical dimensions on the 2D drawing rather than relying on general tolerance claims.
Sheet Metal Fabrication Process at a Glance
| Stage | Factory control | Buyer output |
|---|---|---|
| 1. RFQ and DFM | Drawing, bend, tolerance and weld review | Clear scope and manufacturable design |
| 2. Material | Grade, thickness, finish and certification check | Approved material specification |
| 3. Cutting | Nesting, laser or punching, first-piece check | Accurate flat blanks |
| 4. Deburring and bending | Edge treatment, tooling and bend compensation | Safe edges and stable geometry |
| 5. Joining and hardware | Fixtures, weld sequence, rivets and inserts | Controlled assembly structure |
| 6. Surface finishing | Pretreatment, masking and coating inspection | Specified appearance and protection |
| 7. QC and packing | Fit, dimensions, finish, labels and protection | Export-ready finished parts |
1. RFQ, Drawing and DFM Review
Production starts with the information supplied by the buyer. A useful RFQ normally includes a STEP or STP model, a 2D PDF drawing, material and thickness, quantity, finish, hardware, critical tolerances and packaging requirements. DXF files may help laser nesting, but they do not replace the tolerance and finish notes on a controlled drawing.
During DFM review, MSTFAB checks bend radius, hole-to-bend distance, tool access, weld access, tolerance stack-up and assembly sequence. A design issue found here is a drawing update. The same issue found after coating becomes scrap, delay and extra freight. See the sheet metal RFQ drawing checklist for a faster quotation package.
2. Material Selection and Preparation
Material choice affects strength, weight, corrosion resistance, bend behavior, welding, appearance and total cost. Common options include SPCC cold rolled steel for painted indoor parts, SECC or galvanized steel for added corrosion protection, SUS304/SUS316 for hygiene or harsh environments, and aluminum 5052 for lightweight formed enclosures.
The factory should confirm grade and thickness before cutting, protect cosmetic sheet surfaces and separate stainless steel from carbon steel contamination. For project-specific guidance, use the sheet metal material selection guide.
3. Laser Cutting or CNC Punching
Flat blanks are produced according to the approved drawing. Fiber laser cutting is flexible for prototypes, mixed geometry, slots and custom openings. CNC punching can be efficient for repeated holes, louvers and larger production runs when tooling is suitable.
A first-piece check should confirm outside dimensions, hole positions and cut quality before the full batch continues. Good nesting improves sheet utilization, but it must not compromise grain direction, cosmetic protection or part identification.
4. Deburring, Edge Treatment and CNC Bending
Cut parts are deburred so edges are safe for handling, coating and assembly. Visible edges may need additional brushing or grinding. The parts then move to CNC press brake bending, where tooling, bend deduction, material springback and bend sequence determine final geometry.
Buyers should identify dimensions that control door fit, rail position, mating panels or gasket compression. These dimensions deserve first-article inspection and in-process checks. Learn more about MSTFAB’s CNC sheet metal bending capability.
5. Welding, Riveting and Hardware Insertion
Parts may be joined by TIG welding, MIG welding, spot welding, riveting, clinching or mechanical fasteners. The correct method depends on strength, appearance, heat distortion, service access and cost. Continuous welding is not always better; unnecessary weld length can add distortion, grinding and labor.
Fixtures and a controlled weld sequence help maintain squareness and door alignment. PEM nuts, studs, rivet nuts and grounding points should be inserted with the correct orientation and pull-out requirement.
6. Surface Finishing and Powder Coating
Surface finishing may include powder coating, brushing, polishing, anodizing, plating or passivation. Final appearance depends on earlier fabrication: burrs, weld distortion and grinding marks remain visible after finishing.
For powder-coated parts, confirm pretreatment, color or RAL reference, texture, gloss, masking areas and coating thickness. Threads, grounding points and electrical contact surfaces often require masking. Outdoor projects also need the substrate, pretreatment and coating system reviewed together.
7. Assembly, Quality Inspection and Export Packing
Final inspection should verify drawing dimensions, door and panel fit, hardware, finish, labels and buyer-defined critical features. Depending on the project, checks may include calipers, height gauges, thread gauges, coating thickness measurement, gasket continuity or assembly fit testing.
Export packaging is part of manufacturing quality. Foam, protective film, corner guards, labeled accessory bags, pallets or wooden cases should match the part weight, finish and shipping method. This reduces scratches, deformation and missing hardware after international transport.
Typical Tolerances: What Buyers Should Specify
General figures are useful for early planning, but they are not a substitute for drawing-specific requirements. Material thickness, part size and geometry affect what is practical.
| Feature | Planning reference | Buyer note |
|---|---|---|
| Laser-cut profile | Often ±0.10 to ±0.20 mm | Confirm material and sheet size |
| Bent dimensions | Often ±0.30 to ±0.50 mm | Identify functional flange dimensions |
| Bend angle | Often ±0.5° to ±1° | Springback varies by material |
| Welded assembly | Project-specific | Define datums and inspection method |
OEM Buyer Checklist Before Production
Revision, datums, critical tolerances and approved sample are clear.
Material, finish, hardware, assembly, inspection and packing are included.
Fit, finish and functional dimensions are approved before batch production.
Frequently Asked Questions
What files are best for a sheet metal fabrication quote?
Send a STEP or STP model plus a controlled 2D PDF drawing. Include material, thickness, finish, quantity, hardware, critical tolerances and packaging requirements.
Is laser cutting always the first production operation?
Usually, but not always. The route depends on the part. Some projects use CNC punching, saw cutting or pre-finished stock before forming and assembly.
When should a buyer request a first article?
A first article is recommended for new products, appearance-sensitive parts, tight assemblies and projects with custom hardware or coatings.
Can MSTFAB support prototypes and repeat OEM batches?
Yes. MSTFAB supports drawing review, prototypes, low-volume production and repeat OEM manufacturing for custom enclosures, cabinets and sheet metal assemblies.
Send Your Drawings for a Process Review
Upload STEP/PDF files, material, finish, quantity and critical dimensions. MSTFAB will review the manufacturing route and quotation scope before production.
Request a QuoteReviewed by: MSTFAB engineering and quality team, Guangzhou, China. Last reviewed June 2026.
MSTFAB provides TIG and MIG sheet metal welding services for structural assemblies, cabinets, frames and OEM metal components.
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