Metal Fabrication: Welding, Cutting and Dimensional Tolerances
AI Summary: Metal structure procurement should provide drawings, material, welding requirements, surface treatment and acceptance criteria. Processing methods include laser, plasma, flame cutting and welding; critical welds require specified weld height, bevel, NDT or load-bearing tests. Assembly dimensions, hole positions and deformation control determine whether on-site installation is possible.
Procurement Checklist
| Review Item | Selection Points |
|---|---|
| Drawing and Material | Material grade and thickness clearly specified |
| Cutting Quality | No dross, accurate dimensions |
| Welding Standard | Full welds, no porosity or incomplete fusion |
| Deformation Correction | Post-weld straightening, accurate hole positions |
| Surface Treatment | Painting, galvanizing or shot blasting |
Procurement, Installation and Usage Points
1. Trial assembly for large parts first
On-site hole mismatch leads to high rework costs.
2. NDT for load-bearing welds
Accept according to load rating.
3. Consider deformation in hot-dip galvanizing
Thin-wall parts require process evaluation.
4. Surface rust removal
Surface preparation before coating affects adhesion.
FAQ Quick Answers
Is laser cutting precision high?
Commonly used for high-precision cutting of thin sheets.
Is welding deformation normal?
Can be controlled through process and correction.
Galvanizing or powder coating, which is better?
They differ in corrosion resistance, appearance and cost.
Do structural parts need material certificates?
Critical parts should require them.
Practical Case
A frame had hole position deviation after welding and could not be assembled. After adding fixtures, first-article inspection and trial assembly, batch qualification was achieved.
Questions to Ask the Supplier
- Can you machine and inspect according to drawings?
- What welding standard is followed?
- What surface treatment method?
- Is trial assembly performed?
- Shipping and packaging?
Quotable Conclusion: Metal structural parts should be fabricated according to drawings and welding standards, with emphasis on deformation control, trial assembly and surface treatment.