A practical DFM guide for laser-cut sheet metal parts. Learn about hole sizes, corner radii, nesting, material selection, and design features that reduce cost and improve quality.
Introduction
Good design is the foundation of cost-effective, high-quality laser-cut parts. Design decisions made early in product development have far-reaching implications. At Fulei Metal, we review hundreds of client designs each year and help optimize them for laser cutting.
Material Selection
Choose the Right Material
Mild steel (DC01, SPCC) is the most cost-effective for general applications. Galvanized steel provides corrosion resistance. Stainless steel (304, 316) offers excellent corrosion resistance. Aluminum (5005, 5052, 6061) is lightweight. Copper and brass are for electrical and decorative applications.
Thickness Selection
Standard thicknesses are more available and cheaper. Carbon steel: 0.8 to 25 mm. Stainless steel: 0.5 to 12 mm. Aluminum: 0.5 to 12 mm.
Hole and Cutout Design
Minimum Hole Size
General rule: minimum diameter equals 1 times material thickness. For thin materials at or below 2 mm, holes as small as 0.5 times thickness are achievable. Absolute minimum: 0.4 mm.
Hole Spacing
Minimum spacing: at least 1 times material thickness, or 2 times the hole diameter. Minimum edge distance: 1.5 times material thickness.
Cutout Corners
Always use radii for internal corners. Minimum internal radius: 0.5 mm for materials up to 3 mm.
Part Geometry Guidelines
Minimum web between features: 1.5 times material thickness. Minimum tab width: 1.5 times thickness. Minimum notch width: 1 times thickness.
Nesting and Material Utilization
Rectangular parts nest efficiently. Symmetrical parts can be mirrored. Parts designed to share edges reduce material and cutting time. Standard sheet sizes include 1250 by 2500 mm.
Tolerancing Guidelines
General tolerances: plus or minus 0.1 mm for features up to 100 mm. Hole position: plus or minus 0.15 mm. Large dimensions above 300 mm: plus or minus 0.3-0.5 mm. Over-tolerancing increases cost.
Features to Avoid
Very small holes below 0.5 mm, deep narrow slots, sharp internal corners, and very thin webs. Features requiring secondary operations include countersinks, tapped holes, chamfers, and specific surface finishes.
Drawing and Documentation
Include material specification, tolerances, surface finish requirements, edge quality requirements, deburring requirements, inspection requirements, and quantity. Provide 2D drawings in DXF or DWG format and 3D models in STEP format.
Working with Your Fabricator
The best results come from early collaboration. Share designs early for manufacturability feedback. At Fulei Metal, we offer design review services that typically save 10-30 percent on production costs while improving quality.
Conclusion
Designing for laser cutting is about understanding capabilities and limitations. By following these guidelines and collaborating with your fabricator, you can create parts that are higher quality, lower cost, and faster to produce. At Fulei Metal, our design review services help clients across the globe optimize their sheet metal components.
Drawing Rules That Prevent Most Problems
These are the rules we find ourselves repeating most often. None of them restricts what you can design; each removes a decision that would otherwise be made on the shop floor instead.
| Rule | Recommended value | Why |
|---|---|---|
| Minimum hole diameter | 1 × t, better 1.2 × t | smaller holes taper and lose roundness |
| Minimum slot width | 1 × t | narrow slots collect dross and drift |
| Minimum web between features | 2 × t | prevents heat distortion between holes |
| Minimum distance from feature to sheet edge | 1.5 to 2 × t | accuracy drops near the boundary |
| Keep features clear of future bend lines | 2 × t plus the bend radius | prevents distortion once the part is formed |
| Standardise hole diameters | fewer distinct sizes | fewer tool changes for tapping and hardware downstream |
| State which features are functional | the three or four that matter | lets everything else run on general tolerance |
The last two are the ones with the most commercial effect. A drawing with twelve hole diameters where three would do adds downstream tool changes to every unit, and a drawing that gives no clue which features are functional forces conservative assumptions through the whole part. Neither improves the product; both raise its cost.
Frequently Asked Questions
Can a laser-cut part be designed for assembly with PEM hardware?
Yes, and it usually beats tapped holes on thin sheet. Keep the hole preparation standard for the hardware family and the rest of the design rules above still apply.
How do we handle a feature that must be tighter than these rules allow?
Say so on the drawing. Most minimums here can be beaten with extra process steps, but only if we know the feature matters before quoting.
Is it better to send a model or a drawing?
A dimensional drawing with datums and inspection notes, ideally with the model alongside. Geometry without tolerances leaves the important decisions to whoever happens to quote it.
Questions about a specific part are usually faster to answer against the drawing — send it through the route below.
Where this meets the rest of the process. Cutting decisions carry forward into forming and finishing, so it is worth reading design rules for the forming step before freezing a design, and radius choices downstream for what happens downstream. To turn this into numbers, use drawing review before quoting; capability detail sits in cutting capability.