CNC Machining¶
数控加工
Computer Numerical Control (CNC) machining is a subtractive manufacturing process that typically uses computerized controls and machine tools to remove layers of material from a stock piece—known as the blank or workpiece—and produces a custom-designed part.
数控加工（CNC）是一种减材制造工艺，通常使用计算机控制和机床从毛坯（工件）上去除材料层，从而生产出定制设计的零件。
Cases (案例)¶
1. Working Principle (工作原理)¶
The process starts with a 3D CAD model, which is converted into a series of computer instructions (G-code) that control the machine's movement.
该过程从 3D CAD 模型开始，将其转换为一系列控制机床运动的计算机指令（G 代码）。
Key Components (关键组件)¶
- Spindle (主轴): Holds and rotates the cutting tool.
- 夹持并旋转刀具。
- Table (工作台): Holds the workpiece.
- 固定工件。
- Axis (轴): Directions of movement (X, Y, Z, A, B, C).
- 运动方向（X, Y, Z, A, B, C）。
2. Equipment Types (设备类型)¶
3-Axis CNC (三轴 CNC)¶
- Description: Moves in X, Y, and Z axes. Best for simple parts.
- 描述：在 X、Y、Z 轴方向移动。最适合简单零件。
- Pros: Lower cost, simple programming.
- 优点：成本低，编程简单。
- Cons: Multiple setups required for complex geometries.
- 缺点：复杂几何形状需要多次装夹。
5-Axis CNC (五轴 CNC)¶
- Description: Adds two rotary axes (A and B/C). Allows machining of complex shapes in a single setup.
- 描述：增加了两个旋转轴（A 和 B/C）。允许在一次装夹中加工复杂形状。
- Application: Aerospace, medical implants, complex consumer electronics housings.
- 应用：航空航天、医疗植入物、复杂的消费电子外壳。
Turn-Mill Center (车铣复合)¶
- Description: Combines turning (lathe) and milling capabilities.
- 描述：结合了车削（车床）和铣削功能。
- Application: Cylindrical parts with milling features (e.g., shafts with slots).
- 应用：带有铣削特征的圆柱形零件（例如带槽的轴）。
3. Equipment Selection (设备选型)¶
When selecting a CNC machine, consider the following parameters:
选择 CNC 机床时，请考虑以下参数：
- Travel Range (行程范围): Does the workpiece fit within the machine's working envelope?
- 工件是否在机床的工作范围内？
- Spindle Speed (主轴转速): High speed (20k+ RPM) for small tools/aluminum; Low speed, high torque for steel/titanium.
- 高转速（20k+ RPM）适用于小刀具/铝合金；低速大扭矩适用于钢/钛合金。
- Accuracy & Repeatability (精度与重复定位精度): Critical for tight tolerance parts (e.g., +/- 0.005mm).
- 对于紧公差零件（如 +/- 0.005mm）至关重要。
- Tool Magazine Capacity (刀库容量): Number of tools required for the operation.
- 加工所需的刀具数量。
4. Key Process Parameters (关键工艺参数)¶
- Cutting Speed (Vc): The speed at which the cutting edge moves relative to the workpiece.
- 切削速度：切削刃相对于工件移动的速度。
- Feed Rate (f): The distance the tool travels during one revolution of the spindle.
- 进给率：主轴旋转一周刀具移动的距离。
- Depth of Cut (ap): The thickness of material removed in one pass.
- 切削深度：一次走刀去除的材料厚度。
5. Common Defects & Troubleshooting (常见缺陷与排查)¶
| Defect (缺陷) | Possible Cause (可能原因) | Solution (解决方案) |
|---|---|---|
| Chatter (颤纹) | Tool overhang too long, unstable fixture | Shorten tool, improve fixture rigidity |
| Burrs (毛刺) | Dull tool, incorrect feeds/speeds | Change tool, optimize parameters |
| Dimensional Variation (尺寸变异) | Thermal expansion, tool wear | Warm-up machine, implement tool life management |