—–|—–|—–|—–|
| Accuracy | ±0.5% (±0.5mm min) | ±0.05mm | ±0.3% (±0.3mm min) |
| Surface Finish | Layer lines visible | Smooth, near injection-molded | Slightly grainy |
| Material Options | 100+ thermoplastics | 20-40 photopolymers | 10-15 thermoplastics |
| Part Strength | Isotropic, strong | Anisotropic, moderate | Isotropic, excellent |
| Max Part Size | 914×610×914mm | 736×635×533mm | 482×482×431mm |
| Lead Time | 1-3 days | 2-5 days | 3-7 days |
| Cost per Part | $ (cheapest) | $$ (moderate) | $$$ (higher) |

### FDM: The Workhorse of Additive Manufacturing

FDM (Fused Deposition Modeling) is the most accessible and cost-effective process for functional prototypes, jigs, fixtures, and end-use parts.

**Best For:**
– Functional prototypes that need real-world testing
– Manufacturing tooling (jigs, fixtures, EOAT)
– Low-volume production parts (up to ~100 units)
– Large parts (up to 1 meter)
– Parts requiring specific engineering thermoplastics (PA-CF, PPA, ULTEM)

**Limitations:**
– Visible layer lines (post-processing required for cosmetic parts)
– Anisotropic strength (weaker in Z-axis)
– Limited resolution for fine details (<0.5mm features) - Support material required for overhangs **Material Highlights:** PLA, PETG, ASA, Nylon-CF, PPA-CF, PPS-CF, TPU, PC, ULTEM ### SLA: Precision and Surface Finish SLA (Stereolithography) uses a laser to cure liquid resin layer by layer, producing parts with exceptional surface quality and fine detail. **Best For:** - Visual prototypes and presentation models - Master patterns for casting and molding - Dental and medical models - High-detail consumer product prototypes - Form-and-fit testing with near-production surface quality **Limitations:** - Photopolymer materials have limited long-term durability - Parts yellow/become brittle with UV exposure - Smaller build volumes than FDM - Post-processing required (washing, curing) - Higher material cost **Material Highlights:** Standard (white/grey/clear), Tough, Durable, High-Temp, Flexible, Castable, Ceramic-filled, Bio-compatible ### SLS: Production-Grade Thermoplastic Parts SLS (Selective Laser Sintering) uses a laser to fuse nylon powder into solid parts — no supports needed, making it ideal for complex geometries and functional end-use parts. **Best For:** - Functional end-use parts in production quantities - Complex assemblies with moving parts - Parts with internal channels or lattice structures - Living hinges and snap-fit features - Low-to-medium volume production (100-10,000 units) **Limitations:** - Higher cost per part than FDM - Surface finish is grainy (can be smoothed) - Limited color options (mostly white/grey nylon) - Longer lead times - Minimum wall thickness: 0.8-1.0mm **Material Highlights:** PA12 (general purpose), PA11 (ductile, higher elongation), TPU (flexible), PA12-GF (glass-filled, rigid), PA12-CF (carbon-filled) ### Decision Framework **Choose FDM when:** - Cost is the primary concern - You need specific engineering materials (PEI, PEEK, PPS) - Parts are large (>400mm in any dimension)
– You are iterating rapidly

**Choose SLA when:**
– Surface finish and fine detail are critical
– You need clear/transparent parts
– The part is a visual prototype or master pattern
– Accuracy is more important than durability

**Choose SLS when:**
– Parts will be used in production
– Design has complex geometries or internal features
– No support removal is desired
– Quantity is 50-1,000+ units
– Isotropic mechanical properties matter

### The Hybrid Approach

Many engineering teams use multiple processes:
– FDM for early-stage functional prototypes
– SLA for design reviews and client presentations
– SLS for pre-production validation and pilot runs
– Then transition to injection molding at scale

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