Il manifatturiero ha due pesi massimi: produzione sottrattiva (tagliare via materiale) E produzione additiva (costruire strato dopo strato). Entrambi trasformano le materie prime in parti, ma funzionano in modi opposti, ciascuno con punti di forza unici per progetti diversi. Sia che tu stia realizzando una staffa di metallo, un prototipo in plastica, o uno strumento medico complesso, scegliere quello sbagliato può far perdere tempo, soldi, o rovinare la performance della tua parte. This guide breaks down their differences, uses real-world cases to show how they work, and gives you a step-by-step way to pick the right one.
Primo: What Are Subtractive and Additive Manufacturing?
Before comparing them, let’s get clear on what each process does. They’re opposites, and that’s why their uses vary so much.
Produzione sottrattiva: “Cutting Down to Size”
Subtractive manufacturing starts with a solid block, plate, or rod of material (come l'alluminio, acciaio, o plastica) and removes excess material to shape it. Think of carving a statue from a stone block—you take away what you don’t need until you get the design you want.
The most common subtractive method is Lavorazione CNC, which uses computer-controlled tools (trapani, mulini, torni) to cut with precision. Other subtractive processes include laser cutting (for 2D shapes), taglio a getto d'acqua (for tough materials like metal), ed elettroerosione (for tiny, detailed cuts).
Caratteristica chiave: Relies on “removing” material—so the final part’s strength comes from the original solid material (no weak layers).
Produzione additiva: “Building Layer by Layer”
Produzione additiva (better known as 3D printing) builds parts from the bottom up, stacking thin layers of material (polvere, filamento, or liquid resin) until the design is complete. Imagine stacking sheets of paper to make a 3D cube—each layer sticks to the one below.
Popular additive methods include:
- FDM (Modellazione della deposizione fusa): Uses plastic filament (like PLA or ABS) melted through a nozzle.
- SLS (Sinterizzazione laser selettiva): Uses a laser to fuse nylon powder into parts.
- mjf (Fusione multigetto in nylon HP): Uses liquid agents and heat to bond nylon powder.
- SLM (Fusione laser selettiva): Uses a laser to melt metal powder (for metal parts like titanium implants).
Caratteristica chiave: Relies on “adding” material—layers can create complex shapes, but they may leave weak spots between layers (called anisotropy).
Side-by-Side Comparison: Key Differences That Matter
To choose between them, you need to compare their performance on the factors that affect your project: costo, velocità, opzioni materiali, e altro ancora. The table below breaks down the critical differences (data from manufacturing industry studies and real-world quotes):
| Fattore | Produzione sottrattiva (per esempio., Lavorazione CNC) | Produzione additiva (per esempio., 3D Stampa) |
| Material Range | Wide—metals (alluminio, acciaio, titanio), plastica, legna, bicchiere, calcolo, schiuma. | Limited—mostly plastics (nylon, PLA, ABS), some metals (titanio, steel via SLM). |
| Forza della parte | High—solid material means parts are isotropic (strong in all directions). No layer weaknesses. | Medium—parts are anisotropic (weaker along layer lines). SLM metal parts are strong but costly. |
| Precision/Tolerance | Very high—tolerances as tight as ±0.025 mm (great for tight-fit parts like gears). | Lower—tolerances down to ±0.1 mm (SLM/DMLS is better, but still not as tight as CNC). |
| Complessità | Best for simple-to-moderate shapes (buchi, discussioni, superfici piane). Struggles with hollow/lattice designs. | Best for complex shapes (reticoli, interni cavi, organic curves). Can make designs CNC can’t. |
| Velocità (Piccoli lotti: 1–10 parti) | Slower—setup takes time (selezione dello strumento, machine programming). A metal bracket takes 2–4 hours. | Faster—no setup beyond uploading a CAD file. A plastic bracket takes 1–2 hours (FDM/MJF). |
| Velocità (Grandi lotti: 100+ parti) | Faster—setup costs are spread over more parts. 100 metal brackets take 8–12 hours (CNC). | Slower—each part is built layer by layer. 100 plastic brackets take 20–30 hours (mjf). |
| Costo (Piccoli lotti: 10 parti) | Higher—setup fees (\(50–)200) plus material waste. 10 aluminum brackets cost ~$150 total. | Lower—no setup fees, meno spreco di materiale. 10 plastic brackets (mjf) cost ~$80 total. |
| Costo (Grandi lotti: 100 parti) | Lower—setup fees spread out. 100 aluminum brackets cost ~$500 total. | Higher—layer-by-layer printing adds time/material costs. 100 plastic brackets (mjf) cost ~$600 total. |
| Rifiuti materiali | High—50–70% of raw material is cut away (chips/scraps). Some can be recycled, but most is waste. | Low—only uses material needed for the part. 3Stampa D (SLS/MJF) reuses 50%+ of unused powder. |
| Post-elaborazione | Minimal—parts often have smooth finishes. May need sanding or polishing for aesthetics. | Required—parts have layer lines or loose powder. Needs cleaning (for SLS/MJF) or sanding (per FDM). |
Real-World Cases: When to Use Each (And Why)
Numbers tell part of the story—but real projects show how these differences play out. Let’s look at three examples where the choice between subtractive and additive made or broke the project.
Caso 1: Metal Automotive Brackets (Large Batch)
A car parts supplier needed 500 aluminum brackets for a new SUV model.
- Additive Option (SLM): Each bracket would cost \(12 (metal powder is expensive), più \)200 for setup. Totale: \(12×500 + \)200 = $6,200. Tempi di consegna: 2 settimane (layer-by-layer printing is slow for large batches).
- Subtractive Option (Lavorazione CNC): Each bracket cost \(5 (aluminum block is cheap), più \)300 for setup. Totale: \(5×500 + \)300 = $2,800. Tempi di consegna: 3 giorni (CNC is fast for repeatable parts).
Risultato: The supplier chose CNC machining—saved $3,400 and got parts 11 days faster. The brackets needed to be strong and fit tightly (tolerance ±0.05 mm)—CNC’s precision was perfect.
Caso 2: Custom Medical Surgical Guides (Piccolo lotto)
Serve una clinica odontoiatrica 5 custom surgical guides (nylon PA12) for implant surgeries. Each guide had to fit a patient’s unique jaw shape (complesso, organic design).
- Subtractive Option (Lavorazione CNC): The complex shape would require custom tools (\(1,000 impostare) E 10 hours of machining per guide. Totale: \)1,000 + (\(50×5) = \)1,250. Tempi di consegna: 1 settimana.
- Additive Option (mjf): No setup fees—just upload the patient’s 3D scan. Each guide took 2 hours to print. Totale: \(30×5 = \)150. Tempi di consegna: 2 giorni.
Risultato: The clinic chose MJF—saved $1,100 and got guides 5 days faster. The guides didn’t need ultra-tight tolerances (±0.1 mm was enough), and MJF’s ability to make complex shapes was critical.
Caso 3: High-Temperature Engine Part (Metallo, Piccolo lotto)
An aerospace startup needed 3 titanium engine parts that could handle 600°C heat. The parts had a hollow interior to reduce weight (complex design).
- Subtractive Option (Lavorazione CNC): Titanium is hard to cut—tools would wear out fast (\(800 impostare) and take 8 hours per part. The hollow interior would need extra steps (drilling from both sides). Totale: \)800 + (\(100×3) = \)1,100. Tempi di consegna: 5 giorni.
- Additive Option (SLM): SLM melts titanium powder into the complex shape—no extra steps. Each part took 4 hours to print. Totale: \(200×3 = \)600. Tempi di consegna: 3 giorni.
Risultato: The startup chose SLM—saved $500 and got parts with the exact hollow design they needed. SLM’s metal parts are strong enough for high heat, and the small batch made additive cost-effective.
Passo dopo passo: How to Choose Between Them for Your Project
Segui questi 4 simple steps to pick the right process—no guesswork needed.
Fare un passo 1: Define Your Project’s Core Needs
Start by asking:
- What material do you need? (Metallo? Plastica? Legna?)
- How many parts do you need? (1–10? 100+?)
- How complex is the design? (Simple holes? Complex lattices?)
- What tolerance do you need? (±0,025 mm? ±0,1 mm?)
Esempio: If you need 200 steel brackets (simple design, tolerance ±0.05 mm), your core needs are “metal, large batch, simple shape, tight tolerance.”
Fare un passo 2: Match Needs to Process Strengths
Use this cheat sheet to narrow down:
| Core Need | Best Process |
| Metal parts, large batch, simple shape | Sottrattivo (Lavorazione CNC) |
| Plastic parts, small batch, complex shape | Additive (MJF/SLS/FDM) |
| Metal parts, small batch, complex shape | Additive (SLM) |
| Wood/glass/stone parts (any batch) | Sottrattivo (CNC/Waterjet) |
| Tight tolerance (±0,025 mm) (any material) | Sottrattivo (CNC) |
Fare un passo 3: Calculate Total Cost (Don’t Forget Hidden Fees)
Cost isn’t just per-part price—include setup fees, rifiuti materiali, e post-elaborazione:
- Sottrattivo: Add setup fees (\(50–)500) e rifiuti materiali (50–70% of raw material cost).
- Additive: Add post-processing costs (\(2–)10 per part for cleaning/sanding) E, for metal, higher material costs.
Esempio: 50 plastic parts (nylon PA12):
- Sottrattivo: \(2 per parte + \)100 impostare + \(50 material waste = \)250 totale.
- Additive (mjf): \(3 per parte + \)30 post-processing = $180 totale.
Additive is cheaper here.
Fare un passo 4: Test with a Prototype (If You’re Unsure)
If you’re on the fence, make a single prototype with both processes (if budget allows). Test the prototype for strength, adatto, and finish—this will tell you which process works better for the final batch.
Tip: For plastic prototypes, use FDM (cheap, veloce). Per prototipi in metallo, use SLM (if complex) or CNC (if simple).
Yigu Technology’s Perspective on Subtractive vs. Produzione additiva
Alla tecnologia Yigu, we don’t force one process—we match it to your project’s goals. For clients needing large batches of metal parts (come le staffe automobilistiche) or wood/glass components, we recommend CNC machining for its speed and cost savings. For small batches of complex plastic parts (like medical guides) or intricate metal parts (come i componenti aerospaziali), we use 3D printing (MJF/SLM). We also help with prototypes: FDM for quick plastic tests, CNC for precise metal fits. Our team calculates total costs (impostare, sciupare, post-elaborazione) upfront, so you never have surprises. For us, the best process is the one that makes your part well, on time, and within budget.
Domande frequenti
1. Can I use additive manufacturing for metal parts instead of subtractive?
Yes—but only if you have a small batch or complex design. SLM (stampa 3D in metallo) makes great complex metal parts, but it’s 2–3x more expensive than CNC for large batches. For simple metal parts (like bolts) or batches over 50, CNC is cheaper and faster.
2. Is additive manufacturing always better for complex shapes?
Almost always—additive can make hollow lattices, organic curves, and internal features that CNC can’t reach. The only exception is if the complex shape can be split into simpler parts that CNC can make, then assembled. Per esempio, a complex plastic housing might be cheaper to CNC as two parts and glue together than to 3D print as one.
3. Which process produces less waste?
Additive manufacturing is far more efficient—SLS/MJF reuse 50%+ of unused powder, and FDM uses only the filament needed for the part. Subtractive manufacturing wastes 50–70% of raw material (chips/scraps), even with recycling. If sustainability is a priority, additive is the better choice.