CNC machining offers exceptional precision and flexibility, making it ideal for small batch production, prototyping, and complex parts. The die casting process, on the other hand, is more cost-effective for large-volume production and provides consistent quality and smooth surfaces. Choosing which process depends on your specific precision, cost, lead time, and design complexity needs.
This article will take a closer look at the differences between CNC machining and high-pressure die casting in terms of process flow, cost structure, precision performance, material utilization, and application scenarios. Read on to help you make the best decision for your next project.
CNC Machining vs. Die Casting: A Head-to-Head Comparison
Tolerance and Precision
CNC machining typically achieves a high precision of ±0.01 mm, making it ideal for demanding parts.
Die casting parts have good dimensional consistency, but critical areas often require secondary machining.
For parts with extremely tight dimensional requirements, CNC machining may have advantages.
Design Flexibility
CNC can directly read CAD drawings to manufacture parts, and can be processed immediately after design updates, without the need for molds.
The die casting mold is necessary, and any design changes will increase costs and delay production cycles.
For projects where the design is frequently optimized, CNC may be more suitable.
Cost Structure
CNC has a low initial investment, but a high unit cost. Die casting molds are expensive, but the unit cost is extremely low in large quantities.
CNC is suitable for small batches, while aluminum die casting products are preferred for large batches.
Production Scale
CNC processing is suitable for small to medium batches, especially customized or prototype products.
The die casting process is suitable for large-scale production, and the mold cost can be amortized quickly.
Delivery Cycle
CNC processing time is short, and samples or small batches can be delivered within a few days.
High-pressure die casting requires the design and manufacture of molds, so the initial preparation cycle is long.
When the project cycle is tight, CNC may be more advantageous.
Material Waste
CNC machining is a subtractive manufacturing method that produces a lot of chips. Although it can be recycled, the cost is high.
Aluminium alloy die casting is close to net shape, with almost no waste and higher material utilization efficiency.
CNC Machining Chips
Surface Treatment
CNC machining can obtain a smooth surface through grinding, polishing, etc., but additional treatment is often required to meet high appearance or functional requirements.
The demolding surface of die casting parts is relatively smooth, which is suitable for most structural parts. If it is used for appearance parts, post-machining is also usually required.
Mechanical Properties
CNC parts are machined from a single piece of raw material, so the strength remains intact.
Porosity may occur in the high-pressure die casting process, but modern technologies such as squeeze casting can effectively control it.
Comparison Table: CNC Machining vs Die Casting
|
Criterias |
CNC Machining | Die Casting |
|
Tolerance |
±0.01 mm or better | Good, may need post-machining |
| Design Changes | Easy and fast via CAD |
Difficult and expensive (requires mold changes or new molds) |
|
Setup Cost |
Low | High (due to mold cost) |
| Unit Cost | High for large runs |
Very low in mass production |
|
Volume |
Ideal for low to mid volumes | Best for high volumes |
| Lead Time | Short (days to a week) |
Longer (due to mold development) |
|
Material Waste |
High (cutting chips) | Low (near-net-shape) |
|
Surface Finish |
Can be excellent for polishing |
Naturally smooth, post-machining is needed per the requirements |
| Strength | Maintains full material integrity |
May have porosity, shrinkage, etc |
Application Fields
Aerospace
CNC machined parts:
-
Structural connection bracket
-
Turbine blade seat ring
-
Guide rail and mounting interface components
-
Precision housing
Aluminium die casting components:
-
Non-load-bearing equipment housing
-
Electronic cabin protection housing
-
Aviation seat adjuster housing
Automobile
CNC machined parts:
-
Motor shaft, sensor seat, interface adapter
-
New energy electric drive system prototype parts
-
High-end customized test parts
Aluminium die casting components:
-
Engine cylinder head cover, gearbox housing
-
Battery pack housing, inverter housing
-
Chassis bracket, steering system housing
Medical
CNC machined parts:
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Orthopedic implants (such as bone screws, bone plates)
-
Surgical navigation bracket
-
Minimally invasive surgical instrument head parts
Aluminium die casting components:
-
Medical equipment housing
-
Handheld device handle and frame
-
Auxiliary support structure
Electronics
CNC machined parts:
-
High-end radiator
-
Precision connector housing
-
Communication module customized housing
Aluminium die casting components:
-
Power adapter housing, charging station housing
-
Display backplane, LED lamp housing
-
Consumer electronics housing
Industrial Equipment
CNC Machining parts:
-
Equipment interface flange
-
Precision fixture parts
-
Pump valve internal components (throttle, guide)
Aluminium die casting components:
-
Motor housing, inverter housing
-
Industrial control box
-
Reducer, gearbox housing
CEX Casting: A Hybrid Solution of Die Casting + CNC Machining
For many parts, combining die casting with CNC machining can achieve the best balance of efficiency and precision.
The die casting process is used for rapid prototyping of complex structures, and CNC is used for machining high-precision details such as holes, threads, and sealing surfaces.
This hybrid solution is particularly suitable for parts such as gearbox housings, engine covers, and structural brackets.
Die casting reduces material waste and initial costs, while CNC machining ensures that key parts meet tolerance requirements.
At CEX Casting, we integrate aluminium alloy die casting and CNC machining under one roof to eliminate outsourcing costs and reduce defects, ensuring full process control from mold to finished product.
We specialize in aluminium alloy die casting and use patented squeeze casting technology to eliminate pores and increase casting strength.
All die casting molds are custom-designed and manufactured in-house, with shorter development cycles and more stable quality.
After casting, the parts are finished in our CNC machining workshop according to the drawing requirements, with tolerances up to ±0.005 mm and surface roughness up to Ra 0.6 μm.
This integrated process helps customers shorten delivery time, reduce costs, and maintain consistent product quality while expanding production capacity.
It is an ideal solution for high-strength and high-precision die casting parts.
CNC Machined Die Casting Parts
Conclusion
CNC machining and die casting are suitable for different manufacturing needs, and they are often best used in combination.
This approach combines high precision, high efficiency, and stability.
As a professional die casting manufacturer, CEX Casting supports both processes and provides a one-stop solution to achieve high-speed mass production of complex die casting products.
Contact us today to get professional advice for your next aluminium alloy die casting project.