Facteurs affectant les coûts d'usinage CNC: Un guide pour les achats & Ingénieurs

Si vous êtes un spécialiste des achats ou un ingénieur produit, Il est essentiel de contrôler les coûts d'usinage CNC pour respecter le budget et proposer des produits compétitifs.. Mais les coûts CNC n'existent pas en vase clos : ils dépendent de tout, de la machine que vous utilisez au nombre de pièces que vous commandez.. Ce guide détaille les 5 core factors that drive CNC machining costs, avec des exemples concrets, data tables, and actionable tips to help you cut expenses without sacrificing quality.

1. Équipement & Machinerie: The Foundation of Cost

Before a single part is machined, your choice of equipment sets the cost tone. Equipment costs include upfront purchase, ongoing operation, and long-term maintenance—and these expenses trickle down to every part you produce.

Key Equipment Cost Drivers

• Type de machine: CNC lathes are simpler and cheaper than CNC milling machines. Milling machines have more moving parts, require more complex assembly, and need skilled operators—so they cost 30–50% more to operate. Par exemple, a small shop machining simple aluminum bolts saved $800/month by using a CNC lathe instead of a milling machine.
• Machine Age & Efficacité: Modern CNC machines (made post-2015) are 2x faster than older models. A manufacturer switching from a 2008 3-axis mill to a 2022 model cut production time for a steel bracket from 45 minutes pour 20 minutes—slashing labor and energy costs by 55%.
• Number of Axes: More axes mean higher costs, but also more capability. 5-axis mills can make complex parts (like aerospace components) in one run, but they cost 2–3x more than 3-axis mills. A medical device company paid $120/hour for 5-axis machining vs. $50/hour for 3-axis—but reduced rework by 80%, so the extra cost paid off.

Cutting Tool Costs (A Hidden Equipment Expense)

Tools aren’t just “accessories”—they’re a recurring cost. The material, revêtement, and design of tools all impact price:

Exemple: A supplier machining 1,000 aluminum brackets switched from steel to carbide tools. Even though carbide tools cost twice as much, they lasted 4x longer—so total tool costs dropped by 50%.

2. Production Preparation Costs: The “Before Machining” Expenses

You can’t machine a part without a plan—and that plan costs money. Production preparation costs include everything needed to turn an idea into a machinable design.

What Goes Into Preparation Costs?

• Conception CAO: Creating a 3D model with software like SolidWorks takes 4–16 hours, en fonction de la complexité. A simple bracket design costs $200–$500, while a complex engine part costs $1,000–$3,000.
• Programmation FAO: Converting the CAD model to G-code (le langage utilisé par les machines CNC) takes 2–8 hours. A freelance CAM programmer charges $75–$150/hour—so a medium-complexity part (like a plastic gear) adds $150–$600 to preparation costs.
• Optimisation de la conception: Fixing flaws (like thin walls or sharp corners) before machining saves money later. A furniture maker spent $300 optimizing a chair leg design—and avoided $2,000 in wasted material from failed parts.

Pro Tip: Pour les petits lots (sous 50 parties), preparation costs can make up 40–60% of total costs. Pour les gros lots (1,000+ parties), these costs are spread out—so they only make up 5–10%.

3. Material Costs: The Biggest Variable

The material you choose is often the single largest cost factor. It’s not just about the price of the raw material—its machinability matters too.

Raw Material Prices (By Type)

Metals are more expensive than plastics, but their prices vary widely. Below is a relative cost comparison (based on 2024 données):

Note: Metal prices fluctuate—titanium, Par exemple, can rise 20% dans 6 months due to supply shortages. Always check current prices before finalizing a design.

Usinabilité: Time = Money

A material’s machinability (how easy it is to cut) directly impacts time—and time is money in CNC machining. Harder materials take longer to machine and wear out tools faster.

Exemple: A aerospace company needed 100 titanium brackets. Machining each took 2.5 heures (contre. 30 minutes for aluminum), and tool costs were $150/part (contre. $20 pour l'aluminium). Total material-related costs were $12,000—5x more than aluminum.

4. Conception & Géométrie: Complexity = Higher Costs

The shape of your part is one of the easiest factors to control—and one of the biggest cost drivers. Simple designs save money; complex designs cost more.

High-Cost Design Features to Avoid

These features force machines to work harder, take longer, or use specialized tools:

• Pointed Internal Corners: CNC tools have rounded tips, so sharp corners need extra steps (like EDM finishing) that add $50–$200/part.
• Thin Walls (Under 1mm): Thin walls bend during machining, requiring slower speeds and more rework. A electronics company added $3/part to fix bent walls on a phone case—until they thickened the walls to 1.5mm, eliminating the issue.
• Deep Cavities (Depth > 4x Diameter): Deep holes need long tools that vibrate, leading to errors. Machining a 10mm-deep cavity (contre. 5mm) ajoute 30% to time and cost.
• Non-Standard Hole Sizes: Drilling a 7.3mm hole (contre. a standard 7mm) requires a custom drill bit that costs $80–$150.

Taille de la pièce: Bigger = More Expensive

Larger parts need more raw material, more machine space, and longer machining times. A 10cm x 10cm aluminum plate costs $5 (matière première), while a 30cm x 30cm plate costs $45—9x more. Plus, machining the larger plate takes 3x longer.

5. Volume de production: Batch Size = Cost Savings

The number of parts you order (volume de production) has a huge impact on unit cost. Larger batches spread out fixed costs (like preparation and setup), so each part costs less.

Batch Size vs. Coût unitaire (Exemple: Aluminium 6061 Bracket)

Key Insight: Ordering 1,000 parts instead of 1 cuts the unit cost by 95%. Even if you don’t need 1,000 parts now, storing extra (if they don’t expire) can save money long-term.

6. Finition des surfaces: The “Final Touch” Costs

Most CNC parts work right off the machine—but some need finishing to improve appearance, force, ou résistance à la corrosion. Each finish adds cost.

Exemple: A garden tool maker added powder coating to aluminum handles. It cost $8/handle, but customer returns dropped by 40% (due to fewer scratches)—so the extra cost was worth it.

Yigu Technology’s Perspective on CNC Machining Costs

Chez Yigu Technologie, we help clients balance cost and quality. For procurement teams, nous recommandons: 1) Choosing aluminum 6061 pour la plupart des projets (great machinability, faible coût); 2) Ordering batches of 100+ to spread preparation costs; 3) Avoiding complex features like thin walls or sharp corners. Pour les ingénieurs, we advise optimizing designs early—small changes (like thickening walls) can cut costs by 20%. We also suggest using 3-axis mills for simple parts and 5-axis only when necessary—this keeps hourly rates low without sacrificing quality.

FAQ

1. How much can I save by switching from steel to aluminum?

En moyenne, aluminum costs 33% less to machine than steel (due to better machinability). Pour 100 parties, that’s $500–$2,000 in savings. Plus, aluminum parts are lighter—saving on shipping costs too. Just make sure aluminum meets your part’s strength needs.

2. Is it cheaper to order 100 parts now or 10 parties 10 times?

Ordering 100 parts now is 70–80% cheaper. Par exemple, 10 parts cost $70 each ($700 total), alors que 100 parts cost $28.50 each ($2,850 total)—but 10 orders of 10 would cost $7,000. Even with storage costs, 100 parts are cheaper long-term.

3. Can design changes really cut CNC costs?

Oui! Simple changes like rounding internal corners, thickening thin walls, or using standard hole sizes can reduce costs by 15–40%. A client of ours saved $1.20/part by changing a 0.8mm wall to 1.2mm—no impact on performance, just lower machining time.