結論を先に (簡単な回答)
短い答えだけが必要な場合:
- Choose 7075 when you need maximum strength and hardness
- Choose 6061 when you need better machinability, 耐食性, and lower cost
ほとんどの CNC 加工プロジェクトでは, 6061 is the default choice, while 7075 is used only when performance truly matters.
⚡ Quick Decision Matrix (Engineer’s Shortcut)
| 要件 | Best Choice | なぜ |
|---|---|---|
| Lowest Cost | 6061 | Easier to machine, lower tooling cost |
| Maximum Strength | 7075 | Nearly 2x the yield strength |
| 耐食性 | 6061 | Better natural resistance |
| 軽量 + Strength | 7075 | Higher strength-to-weight ratio |
| Fast Production | 6061 | Higher cutting speed, less tool wear |
👉 Engineer’s Note: If you don’t have a strong reason to use 7075, 6061 is usually the smarter choice.
📊 6061 対 7075 アルミニウム (Side-by-Side Comparison)
| Property | 6061 アルミニウム | 7075 アルミニウム |
|---|---|---|
| Yield Strength | ~275 MPa | ~503 MPa |
| Hardness | Medium | Very High |
| Machinability | 素晴らしい | Good |
| 耐食性 | 素晴らしい | 適度 |
| 料金 | より低い | Higher |
| Typical Use | General parts | 航空宇宙 / high-load |
👉 This table alone answers most selection questions.
What Is 6061 アルミニウム?
6061 is the most widely used aluminum alloy in CNC machining.
なぜ?
- Easy to machine
- Stable during cutting
- 良好な腐食抵抗
- Cost-effective
In real workshops, if there’s no special requirement:
👉 6061 is usually the first choice
What Is 7075 アルミニウム?
7075 is known as a high-strength aerospace aluminum.7075 is known as a high-strength aerospace aluminum.
Key features:
- Extremely high strength
- 高い硬度
- Better fatigue resistance
But it comes with trade-offs:
- Harder to machine
- More expensive
- Lower corrosion resistance
Key Differences in CNC Machining
1. Strength vs Machinability
This is the biggest trade-off.
- 7075 → stronger, but harder to cut
- 6061 → easier to machine, better surface finish
実際に:
❗7075 puts more load on tools and increases wear
2. Surface Finish Performance
- 6061 → smoother finish (Ra easier to control)
- 7075 → slightly rougher, especially at high speed
3. 工具の摩耗 & 効率
- 7075 → faster tool wear
- 6061 → more stable cutting
👉 This directly affects:
- 料金
- リードタイム
- 一貫性
4. 耐食性
- 6061 → excellent (can be used directly)
- 7075 → requires surface treatment
👉 Especially important for:
- outdoor parts
- marine environments
⚠️ Hidden CNC Machining Costs (What Most Guides Don’t Tell You)
その間 7075 offers superior strength, it comes with hidden machining costs:
- 工具の摩耗: Typically 20–30% higher compared to 6061
- Cutting Speed: Slower feed rates required for stability
- Cycle Time: Longer machining time increases cost per part
👉 Engineer’s Note: Unless your part truly requires high strength (例えば, aerospace or high-torque components), using 7075 can increase cost without delivering real value.
When Should You Choose 7075?
Choose 7075 もし:
- High-load structural parts
- Aerospace components
- Weight reduction + strength requirement
Examples:
- UAV frames
- aircraft brackets
- high-performance gears such as fishing reel gears
When Should You Choose 6061?
Choose 6061 もし:
- General CNC parts
- Enclosures / ハウジング
- Cost-sensitive projects
Examples:
- motor housings
- 備品
- electronic enclosures
⚠️ Real-World Tip (From Machining Experience)
Here’s something many guides won’t tell you:
7075 is not always “better” — it’s only better when needed
In many projects, using 7075 unnecessarily will:
- Increase cost
- Increase machining difficulty
- Provide no real benefit
よくある質問
Is 7075 always stronger than 6061?
はい, significantly stronger in yield strength.
Is 6061 easier to machine?
はい, it offers better chip control and stability.
Which one is better for CNC machining?
👉 6061 for most cases, 7075 for high-performance needs.
Can 7075 replace steel?
In some lightweight applications, yes.
Final Thoughts
Choosing between 6061 そして 7075 is not about which is “better” —
it’s about which is more suitable for your application.
Need Help Choosing the Right Aluminum?
If you’re not sure which material fits your project, feel free to reach out.
👉 We can help you select the right alloy based on strength, cost, and machining requirements.
