Here are the questions you most want to ask about aerospace CNC machining

"Why do aviation parts have to be processed by CNC?" "Is titanium alloy really difficult to process to the point of being 'outrageous'?" "How difficult is it to achieve a precision of 0.001mm?" If you have ever been curious about aerospace CNC machining, but have been stopped by professional terms, this article is your "beginner's guide". We have sorted out some of the most concerned issues for the public - from processing objects to cost cycles, from precision requirements to quality control, and used popular language to dismantle the underlying logic of this "high-cold" technology, so that you can understand the precision manufacturing code behind aviation parts.

1. What is aerospace CNC machining?

Aerospace CNC machining refers to the technology of using computer numerical control (CNC) technology to perform high-precision and high-reliability machining on high-demand parts in the aerospace field (such as aircraft structural parts, engine parts, airborne equipment parts, etc.). Its core is to achieve the manufacturing of complex curved surfaces, thin-walled structures, and high-precision matching parts through customized programming and high-end machine tools to meet the performance requirements of aerospace parts in extreme environments such as high temperature, high pressure, and high speed.

2. What are the parts to be processed? Why do we need CNC machining?

(1) Typical parts:

Structural parts: Aircraft wing ribs, fuselage frames (mostly aluminum alloy/titanium alloy thin-walled parts, high weight reduction requirements, complex structures).

Engine parts: turbine blades (high-temperature alloys, extremely high surface accuracy requirements, requiring five-axis linkage machining), combustion chamber parts.

Turbine blades

Landing gear parts: high-strength steel bearing seats, connectors (require high-precision grinding to ensure load safety).

Precision components: aviation plugs, sensor housings (strict dimensional tolerances, requiring micron-level accuracy).

(2) Necessity of CNC machining in aerospace:

Aerospace parts are mostly complex surfaces + thin walls + high-precision designs. Traditional manual machining cannot meet the accuracy and consistency requirements. CNC machining can achieve automated and standardized production through programming to ensure the reliability of parts under extreme working conditions.

3. What materials are processed? Why is it difficult to process?

(1) Mainstream materials:

Titanium alloys (such as TC4): high strength and high temperature resistance (preferred for aircraft engines), but high cutting resistance and easy to stick to the tool, requiring special tools and cooling processes.

Aluminum alloy (such as 7075): light and high strength (accounting for more than 50% of the aircraft structure weight), but thin-walled parts are easy to deform, and the cutting force and clamping method need to be controlled.

High-temperature alloy (such as Inconel): resistant to high temperatures above 1000℃ (turbine blade material), high hardness, poor thermal conductivity, and extremely low processing efficiency (the processing time is 5 to 10 times that of ordinary steel parts).

Composite materials (carbon fiber/titanium alloy laminates): used for fuselage skins, delamination and burrs must be avoided, and the tool sharpness and cutting parameters are demanding.

(2) Processing difficulties:

Material properties and processability are contradictory (such as high strength leading to rapid tool wear, and lightweight materials are easy to deform), and customized process solutions are required.

4. How high is the precision requirement for aerospace CNC machining? How fine should the surface roughness be?

(1) Dimension tolerance:

Ordinary structural parts: ±0.02mm~±0.05mm (such as fuselage frame holes).

Key matching parts: ±0.001mm~±0.01mm (such as engine bearing installation positions, which require ultra-precision grinding).

Geometric tolerances: Flatness and verticality are often required to be ≤0.01mm (to ensure aerodynamic performance after component assembly).

(2) Surface roughness:

General parts: Ra 0.8~1.6μm (such as the milled fuselage surface).

Key friction surfaces: Ra 0.2~0.4μm (such as landing gear piston rods, which require grinding and polishing to reduce wear).

Aircraft engine blades: Ra≤0.1μm (mirror-grade surface to reduce airflow resistance and fouling).

5. Why is the cost of aerospace CNC machining so high? What factors affect the price?

(1) Expensive materials:

The unit price of titanium alloys and high-temperature alloys is 10~20 times that of ordinary steel, and the material utilization rate is low (such as milling thin-walled parts from a whole block, the cutting removal rate is more than 80%).

(2) High-end equipment:

Requires a five-axis linkage machining center (expensive unit price) and an ultra-precision grinder (equipped with a constant temperature system), and the equipment depreciation cost is high.

(3) Complex process:

Multiple processes in series: rough milling → semi-finishing milling → heat treatment → fine grinding → flaw detection → surface treatment, and the process takes several weeks.

(4) Strict inspection:

Each piece must be inspected, requiring a three-coordinate measuring instrument, fluorescent flaw detection, and CT scanning, and the inspection cost accounts for more than 20%.

(5) Certification threshold:

Needs to pass the AS9100 aviation quality management system certification, and the processing process must be traceable throughout the process (recording cutting parameters, tool numbers, etc.), which increases management costs.

6. How long is the processing cycle? Why can't it be expedited?

(1) Conventional cycle:

Simple structural parts (such as aluminum alloy ribs): 2~4 weeks (including programming, processing, flaw detection, anodizing).

Complex engine parts: 8~12 weeks (requires multiple heat treatments, precision grinding, and multiple rounds of inspection).

(2) Reasons for not being able to expedite:

Materials need to be customized in advance: Special alloys require specific import channels, and the procurement cycle is as long as 1 to 2 months.

Waiting between processes: Heat treatment requires natural aging (such as titanium alloy parts need to be placed for 72 hours to eliminate internal stress), and cannot be compressed.

Strict inspection: Flaw detection and full dimensional inspection must be performed piece by piece, and there is no shortcut for batch inspection.

7. How to ensure processing quality? What to do if there is a problem?

(1) Quality control:

Full traceability: Each aerospace CNC machined part is accompanied by a processing report (including cutting parameters, tool life, and inspection data), which can be checked by scanning the code.

Redundant inspection: The first piece must be inspected, batch sampling, and key dimensions are 100% inspected (such as the engine blade profile needs 3D scanning to compare the digital model).

Environmental control: High-precision processing must be carried out in a constant temperature (20±1℃) and clean workshop to avoid temperature deformation and dust pollution.

(2) Problem handling:

If there are dimensional deviations or internal defects (such as cracks), minor problems can be reworked (such as re-grinding), while serious problems need to be scrapped and remade, and root cause analysis (RCA) needs to be initiated to prevent batch accidents.

8. Summary: The core value of aerospace CNC machining

Aerospace CNC machining is a typical representative of "using technology to break through the limits of materials". It is not only a means of manufacturing parts, but also the "precision cornerstone" of the aviation industry - from micron-level tolerances to extreme environmental reliability, each process carries the mission of "safety first". Despite its high cost and long cycle, it is irreplaceable in improving aircraft performance (such as fuel consumption, life, and safety) and is one of the key technologies supporting the development of the aerospace industry.

If you are interested in precision machining of aerospace parts, the core is to balance performance requirements (such as materials and precision) with actual conditions (cost and cycle). Only by choosing suppliers with AS9100 certification, high-end equipment (such as five-axis machine tools + three-coordinate detection) and rich aviation machining experience can reliable delivery be achieved under strict requirements.

To date, aerospace manufacturing processes have evolved into four major mainstream processes. In addition to the CNC machining technology mentioned in this article, it also includes casting technology, 3D printing technology, and robotic manufacturing technology. The introduction to the other three processing technologies is presented in this article. If you want to know more, you can move on to read it. I believe you will definitely choose the most suitable processing technology for your parts!