Impression 3D en métal: Quand le choisir par rapport à la fabrication traditionnelle (2025 Guide)

Si vous êtes ingénieur ou professionnel des achats, vous vous êtes probablement demandé: Is impression 3D métal worth it for parts we’ve long made with subtractive methods like CNC machining? La réponse n’est pas un simple « oui » ou « non » : cela dépend de votre conception, chronologie, budget, et exigences en matière de pièces. This guide breaks down everything you need to know to make the right choice, avec des exemples concrets et des données exploitables.

What Is Metal 3D Printing? A Simple Overview

Metal 3D printing (aussi appelé fabrication additive, or AM) builds parts layer by layer from metal powder—unlike traditional “subtractive” methods that cut away material from a solid block. Two of the most common technologies are:

• GDT (Fusion laser sélective): Uses a laser to fully melt metal powder into a liquid, which cools and solidifies into layers.
• DMLS (Frittage laser direct des métaux): Heats powder just enough to “weld” particles together (not fully melt them).

While SLM and DMLS work differently, the industry often uses these terms interchangeably. Both contrast sharply with Usinage CNC, which shapes parts by removing material—think of it as carving a statue from a block of stone, versus building one with tiny bricks.

4 Key Scenarios to Choose Metal 3D Printing

Metal 3D printing isn’t better for every job, but it shines in four specific cases. Below are real-world examples and data to back up each scenario.

1. You Need Complex Designs (With No Extra Cost)

Traditional manufacturing struggles with complex shapes—even 5-axis CNC machines can’t easily create intricate geometries like internal channels or lattice structures. Worse, the more complex the design, the higher the cost: you’ll need more precision tools, longer setup times, and often multiple parts to assemble.

Metal 3D printing flips this script: complexity doesn’t add cost. It builds the entire part in one step, no assembly required.

Real-World Example: GE’s LEAP Engine Fuel Nozzle

GE used DMLS to reimagine its LEAP aircraft engine fuel nozzle. Previously, the nozzle was made from 20 separate parts (sourced from different suppliers) that needed assembly. Avec l'impression 3D:

• The nozzle became a single, monolithic part.
• Weight dropped by 25% (critical for fuel efficiency in aerospace).
• Strength increased by 5x compared to the original design.

This wouldn’t have been possible with CNC machining—assembling 20 parts into a tight, high-performance component was too slow and error-prone.

2. You Need Metal Prototypes Fast (1–5 Units)

If you’re testing a new part design (1 à 5 prototypes), metal 3D printing is faster and cheaper than CNC machining. Here’s why:

• CNC machining needs material stock, configuration de l'outil, and programming—often taking 2–4 semaines to get your first part.
• Metal 3D printing (even DMLS) works on-demand: pas d'outillage, no stockpiling. You can print a prototype in 3–7 jours and tweak the design until it’s perfect.

Prototype Turnaround Time Comparison

Par exemple, a medical device company testing a new surgical instrument prototype used GDT imprimer 3 versions in 2 weeks—something that would have taken 6 weeks with CNC machining.

3. You Want Lightweight, Durable Parts (Aerospace/Medical)

Industries like aerospace and medical need parts that are both light (to save fuel or reduce patient discomfort) et fort (to handle high stress). Metal 3D printing uses superalloys (par ex., Inconel 718, AlSi10Mg, Cobalt-Chromium) that are lighter than traditionally machined materials but just as durable.

Comparaison des performances des matériaux

A dental lab, par exemple, utilise 3D-printed Cobalt-Chromium crowns that are 15% lighter than milled crowns but last just as long—patients report less jaw fatigue, and the lab saves time on machining.

4. You Want to Cut Material Waste

Subtractive methods like CNC machining generate a lot of waste: jusqu'à 70% of the original metal block ends up as scrap (which you have to recycle). Metal 3D printing only uses the powder needed to build the part—no excess material, pas de gaspillage.

Par exemple, a automotive parts supplier switched to GDT for a small sensor housing. Previously, CNC machining turned a 1kg aluminum block into a 0.3kg part (70% déchets). Avec l'impression 3D, they use exactly 0.3kg of AlSi10Mg powder—saving $200 per part in material costs.

5 Disadvantages of Metal 3D Printing (When to Choose CNC Instead)

Metal 3D printing isn’t a silver bullet. Here are five cases where CNC machining is still better:

1. You Need Smooth Surface Finishes

3D-printed parts have a grainy surface (from the metal powder layers) that’s not as smooth as CNC-machined parts. You can fix this with post-processing (par ex., ponçage, polissage), but that adds 10–30% to the total cost.

If your part needs a precise texture (par ex., a valve that seals tightly), CNC machining is the better choice—it delivers a smooth finish right off the machine.

2. You Need Maximum Part Strength

CNC-machined parts are cut from solid metal blocks, so they have uniform strength. 3Pièces imprimées en D, par contre, have layer lines that can weaken them. En moyenne:

• Compressive strength of 3D-printed metal parts is 40–50% lower than CNC-machined parts.
• This matters for high-stress parts (par ex., load-bearing brackets in construction).

3. You’re Mass-Producing (100+ Unités)

Metal 3D printing is slow for large batches. A 3D printer can make 10 parts in a day, while a CNC assembly line can make 100+ parts per hour.

Comparaison des coûts: 100 Units of a Small Bracket

For mass-produced parts (par ex., smartphone components), CNC machining is far cheaper and faster.

4. You Need Large Parts

3D printers have strict size limits. The maximum part size for GDT is typically 250 x 250 x 325 mm (about the size of a shoebox). Machines CNC, par contre, can handle parts up to 2000 x 800 x 1000 mm (the size of a refrigerator).

If you’re making large parts (par ex., industrial machine frames), CNC machining is the only option.

5. You Need Rare or Specialized Materials

CNC machining works with hundreds of metals (par ex., laiton, alliages de titane, stainless steel grades 316L and 430). Metal 3D printing has limited options—most providers (like Xometry) only offer 5–10 metal powders (par ex., Inconel 718, AlSi10Mg).

If your part needs a rare material (par ex., Hastelloy C276 for chemical processing), CNC machining is necessary.

Yigu Technology’s Perspective on Metal 3D Printing

Chez Yigu Technologie, we see metal 3D printing as a powerful complement to traditional manufacturing—not a replacement. For clients in aerospace and medical fields, it solves critical problems: complex designs, fast prototypes, and lightweight parts. But we always guide clients to CNC machining for mass production, grandes pièces, or smooth finishes. The key is matching the technology to the job: 3D printing for innovation and small batches, CNC for scale and precision. This hybrid approach helps our clients save time, réduire les coûts, and build better products.

FAQ About Metal 3D Printing

1. Can metal 3D printing replace CNC machining entirely?

Non. Metal 3D printing excels at complex designs, prototypes, and small batches, but CNC machining is better for mass production, grandes pièces, surfaces lisses, and rare materials. The best approach is to use both where they fit.

2. How much does a metal 3D printed part cost compared to CNC?

For 1–10 parts, metal 3D printing is cheaper (par ex., \(500–)1,500 par pièce). Pour 50+ parties, CNC machining becomes cheaper (par ex., \(300–)800 par pièce) because setup costs are spread across more units.

3. What post-processing do metal 3D printed parts need?

Most parts need support structure removal (to take off the “scaffolding” used during printing). For smoother surfaces, you may need sanding, polissage, or chemical finishing—these add 10–30% to the cost but improve performance for tight-fitting parts.