Introduction: The Manufacturing Dilemma

In the world of metal parts production, manufacturers are often faced with a critical decision: should they choose CNC machining or die casting? Both processes are widely used across industries, but the right choice depends on factors such as production volume, material type, tolerance requirements, and cost. Understanding the strengths and limitations of each method can significantly influence your product development timeline and profitability.

What Is CNC Machining?

CNC (Computer Numerical Control) machining is a subtractive manufacturing process where raw metal blocks are precisely shaped using cutting tools controlled by computer programs. It is ideal for:

• Producing high-precision parts with tight tolerances

• Low-to-medium volume production

• Projects requiring design flexibility and frequent iterations

• Materials like aluminum alloys (6061, 7075), stainless steel, and titanium

Advantages:

• High dimensional accuracy and surface quality

• No need for expensive tooling

• Rapid design changes possible

• Suitable for prototyping and low-volume production

What Is Die Casting?

Die casting involves injecting molten metal (usually aluminum, zinc, or magnesium) into steel molds under high pressure. It is a fast and cost-effective method for producing large volumes of identical parts.

Best suited for:

• High-volume production of complex shapes

• Parts with moderate precision and uniform wall thickness

• Non-ferrous metals with good flow characteristics

Advantages:

• Lower cost per part in large quantities

• Excellent repeatability

• Capable of producing intricate geometries

• Fast production cycles

Disadvantages:

• High upfront tooling cost

• Limited to castable materials (e.g., not suitable for 6061 or 7075 aluminum)

• Additional machining often needed for critical features or threads

Cost Comparison: CNC vs Die Casting

CNC Machining Costs:

• Higher per-part cost due to machining time

• No mold investment, which lowers startup costs

• Best suited for 1–1,000+ units or frequent design changes

Die Casting Costs:

• High initial cost due to mold development (often >$10,000)

• Extremely low per-part cost at high volumes (>5,000 pcs)

• Cost-effective only when production scales up significantly

Conclusion: Die casting is more economical for large production runs, while CNC offers greater flexibility and lower risk for early-stage or complex parts.

Surface Finish and Tolerances

• CNC Machining delivers better surface roughness (as low as Ra 0.8 µm) and maintains tight tolerances (±0.01 mm or better), making it ideal for components requiring fine finishes or tight fits.

• Die Casting typically has rougher surfaces (Ra 3.2 µm or higher) and requires post-processing like machining or polishing for critical surfaces.

Application Scenarios: When to Use CNC or Die Casting

To make the right decision, consider the following common scenarios:

This comparison helps clarify that CNC machining is not only for prototypes but also for functional, high-tolerance parts that require reliability and quick iteration. Die casting shines when you need to produce thousands of identical parts at the lowest unit cost.

Choosing the Right Process for Your Project

The choice between CNC and die casting ultimately depends on your priorities:

• Go with CNC if you need high precision, flexible design, and short lead times for low-to-medium volumes.

• Choose die casting when unit cost is your top priority and you’re ready to commit to high-volume runs.

If you’re unsure, a hybrid approach may also be viable—using CNC for initial batches and transitioning to die casting once the design is finalized and volumes justify mold investment.

Final Thoughts & Recommendation

Both CNC machining and die casting are valuable manufacturing technologies, but they serve different purposes. At Tik Precision, we specialize in CNC machining for critical components, especially when precision and flexibility are key. We also provide design consulting to help you plan the best transition to high-volume methods like die casting when the time is right.