3D Impression: Guide de conception ultime pour le moulage par frittage laser (SLS)

If you’re designing parts forLaser Sintering Molding (SLS)- une technologie d'impression 3D par fusion sur lit de poudre de premier plan - un bon design n'est pas seulement « agréable à avoir ». C’est la différence entre une pièce qui se fissure à mi-utilisation et une pièce solide., précis, et rentable. Ce guide détaille toutes les règles de conception critiques pour SLS, avec des exemples concrets, données, and tips to fix common headaches like warping or stuck powder.

1. Why SLS Design Rules Matter

SLS uses lasers to fuse thermoplastic powders (commePennsylvanie 12 or carbon-filled polyamide) into parts. Contrairement à FDM, it doesn’t need support structures—but its powder-based process creates unique design challenges:

• Thin walls can collapse under laser heat.
• Small holes trap unsintered powder (ruining functionality).
• Large flat surfaces warp as the part cools.

Follow these rules, and you’ll cut reprints, save material, and get parts that work right the first time.

2. Critical SLS Design Guidelines (With Data & Exemples)

We’ve organized the most important rules by feature—from wall thickness to text. Each section includes easy-to-use tables and real cases to guide you.

2.1 Wall Thickness: Avoid Collapse & Cracking

Wall thickness is make-or-break for SLS parts. Too thin, and the part will collapse during printing; trop épais, and you waste material (et de l'argent).

Key Recommendations by Material

Real Example:

A manufacturer designed a PA 12 bracket with 0.5 murs mm (too thin!). The laser’s heat melted the thin sections, provoquant 80% of the parts to collapse. When they adjusted to 1.3 murs mm, the success rate jumped to 99%—and they still saved 30% material vs. un 4 mm wall design.

Pro Tip:

Walls thinner than 0.5 mm willoverthicken from the laser’s heat. Stick to the minimums above to avoid distorted parts.

2.2 Hole Sizes: Prevent Trapped Powder

SLS prints holes directly—no need for post-drilling. But small holes trap unsintered powder, which can block fluid flow (for valves) or break the part when you try to remove it.

Must-Follow Hole Rules

• Minimum diameter: 1.5 mm (any smaller traps powder).
• Best practice: Design holes to match standard drill bit sizes (par ex., 2 mm, 3 mm). If the hole needs to be precise, you can drill it slightly larger post-print.

Real Example:

A medical device company printed PA 12 filters with 1.0 trous mm. Après l'impression, they couldn’t remove the trapped powder—rendering 50% of the filters useless. When they increased holes to 1.5 mm, powder came out easily, and the filters worked perfectly for fluid filtration.

2.3 Taille de la pièce: Stay Within Printable Limits

SLS printers have maximum and minimum size limits. Going beyond them leads to failed prints or low precision.

SLS Size Guidelines

Pro Tip:

If your part is larger than 320 x 320 x 580 mm, split it into smaller interlocking pieces. SLS can print parts that fit together perfectly—saving you from oversized print failures.

2.4 Tolérances: Focus Only on What Matters

Tolerance is how much a part’s size can vary. Too many tight tolerances increase print time and cost; too few ruin mating parts (like a lid that won’t fit a box).

SLS Tolerance Facts

• Maximum accuracy: Jusqu'à 0.3% of the feature size (ou 0.3 mm—whichever is larger). Par exemple, un 100 mm part can vary by ±0.3 mm.
• Rule of thumb: Only use tight tolerances for mating surfaces (par ex., a shaft that fits a bearing). For non-critical areas (par ex., a part’s outer edge), loosen tolerances to save time.

Real Example:

An automotive supplier added tight tolerances (±0,1 mm) to every part of an SLS bracket—even the non-mating edges. This doubled print time and cost. When they limited tight tolerances to just the mating hole, they cut costs by 40% with no loss in functionality.

2.5 Hollow Parts: Add Escape Holes for Powder

Hollow parts save weight and material—but you needescape holes to remove residual powder from the cavity.

Hollow Part Rules

• Minimum escape hole size: 3.5 mm (smaller holes trap powder; larger holes let media in for interior polishing).
• Where to place holes: Put them in hidden areas (par ex., the bottom of a hollow cup) so they don’t ruin aesthetics.

Real Example:

A luggage brand printed hollow PA 12 handles with no escape holes. Après l'impression, the trapped powder made the handles heavy and brittle. When they added two 3.5 trous mm, powder poured out easily—the handles were 25% lighter and passed drop tests.

2.6 Interlocking Parts: Print Functional Assemblies in One Go

SLS’s superpower? Printing interlocking, pièces mobiles (like hinges or gears) in a single build—no assembly needed. But you need enough clearance to remove powder.

Interlocking Part Rule

• Minimum clearance: 0.5 mm between moving parts (par ex., a gear and its axle). More clearance (0.8–1.0 mm) is better for easy movement.

Real Example:

A toy company printed a SLS gear set with 0.3 mm clearance. Powder got stuck between the gears, making them lock up. When they increased clearance to 0.5 mm, the gears spun smoothly—no assembly required.

2.7 Engravings, Embossings & Text: Keep Them Visible

SLS can print logos, texte, or details directly on parts—but small details wear off during post-processing (like media tumbling).

Detail Guidelines

Real Example:

A electronics brand printed PA 12 cases with 1.5 mm tall text (too small!). Media tumbling wore the text down, making it unreadable. When they increased text height to 2 mm and used Arial, the text stayed clear—even after polishing.

2.8 Avoid Warping: Skip Large Flat Surfaces

Large flat surfaces (par ex., un 200 mmx 200 mm plate) warp as SLS parts cool. The powder shrinks unevenly, causing the surface to bow or crack.

How to Fix It

• Rule 1: Avoid large flat surfaces whenever possible.
• Rule 2: If you need a flat surface, add côtes (thin support structures) underneath. Ribs should be 0.8–1.0 mm thick and spaced 10–15 mm apart.

Real Example:

A furniture maker printed large flat SLS PA 12 panels (300 mmx 200 mm) with no ribs. 70% of the panels warped by 2–3 mm. When they added 1.0 mm ribs spaced 12 mm l'un de l'autre, warping dropped to less than 0.5 mm—perfect for their furniture designs.

3. Yigu Technology’s Take on SLS Design

Chez Yigu Technologie, we’ve helped hundreds of clients fix SLS design issues. The biggest mistake we see? Overlooking small details—like 0.3 mm clearance for interlocking parts or 1 mm engravings. Nos conseils: Prioritizefunction first—match wall thickness, taille du trou, and clearance to how the part will be used. Par exemple, a medical part needs tighter tolerances than a decorative one. By aligning design with end-use, you’ll get SLS parts that are strong, précis, and cost-efficient—every time.

4. FAQ: Common SLS Design Questions

Q1: Can I print a wall thinner than 0.7 mm for PA 12 if I use support?

Oui, but only down to 0.6 mm—and it’s risky. The laser’s heat can still overthicken or collapse 0.6 murs mm. We recommend sticking to 0.7 mm (no support) for consistent results.

Q2: Why do I need to use Sans serif fonts for SLS text?

Sans serif fonts (no small “tails” on letters) have simpler shapes. This makes them easier for the SLS laser to print clearly, and they’re less likely to break off during post-processing compared to serif fonts (par ex., Times New Roman).

Q3: If my part is larger than 340 x 340 x 605 mm, can I still print it with SLS?

No—SLS printers can’t go beyond their maximum build size. Instead, split the part into smaller interlocking pieces (avec 0.5 mm+ clearance). SLS prints these pieces perfectly, and you can assemble them post-print for a full-size part.