Introduction
Choosing the right metal fabrication process can make or break your product’s performance, cost structure, and time-to-market. With options ranging from high-volume die casting to precision CNC machining, engineers and procurement specialists often struggle to identify the optimal method for their specific application.
As an ISO 9001-certified manufacturer serving industries from automotive to medical devices, we’ve produced 10,000+ custom metal parts using all three processes. This guide provides a data-driven comparison to help you:
✔ Select the most cost-effective process for your production volume
✔ Avoid common design pitfalls that increase manufacturing costs
✔ Balance lead time and quality requirements
1. Process Overview & Key Characteristics
1.1 Sheet Metal Fabrication
Best for: Enclosures, brackets, panels (thin, flat, or bent components)
- Materials: Stainless steel, aluminum (5052, 6061), cold-rolled steel
- Thickness Range: 0.5mm–6mm
- Tolerance: ±0.1mm (standard), ±0.05mm (precision)
- Typical Lead Time: 1–3 weeks
Advantages:
✓ Lowest tooling costs ($500–$5,000)
✓ Ideal for large flat parts (up to 3m x 1.5m)
✓ Fast production for prototypes
Limitations:
✕ Limited to 2D forms with simple bends
✕ Higher labor cost for complex assemblies
1.2 Die Casting
Best for: High-volume complex geometries (housings, gears, connectors)
- Materials: Aluminum (ADC12), zinc (Zamak), magnesium (AZ91D)
- Wall Thickness: 1mm–12mm
- Tolerance: ±0.25mm (standard), ±0.1mm (with machining)
- Typical Lead Time: 4–8 weeks (including mold making)
Advantages:
✓ Excellent surface finish (Ra 1.6μm as-cast)
✓ Highest production speed (100–500 shots/hour)
✓ Minimal post-processing needed
Limitations:
✕ High mold costs ($10,000–$50,000)
✕ Not suitable for low volumes (<1,000pcs)
1.3 CNC Machining
Best for: Precision components (shafts, flanges, surgical tools)
- Materials: Aluminum (7075), stainless (303, 304), titanium
- Feature Size: Down to 0.5mm
- Tolerance: ±0.025mm (standard), ±0.005mm (high-precision)
- Typical Lead Time: 2–5 weeks
Advantages:
✓ Tightest tolerances of all processes
✓ No tooling required for prototypes
✓ Best material flexibility
Limitations:
✕ Highest per-part cost at scale
✕ Significant material waste (up to 70%)
2. Industry-Specific Recommendations
2.1 Automotive Components
| Part Type | Recommended Process | Why? |
|---|---|---|
| Battery enclosures | Sheet metal (laser welding) | Lightweight, large flat areas |
| Transmission housings | Die casting (Aluminum) | Complex shapes, high volumes |
| Sensor mounts | CNC machining | Precision threaded features |
Cost Example: Electric vehicle motor housing
- Die casting: $18.50/unit at 10,000pcs
- CNC machining: $210/unit at 100pcs
2.2 Electronics & Telecommunications
| Part Type | Recommended Process | Why? |
|---|---|---|
| 5G antenna shields | Sheet metal (bending) | EMI shielding, quick iterations |
| Heat sinks | Die casting (Al with fins) | Integrated cooling geometry |
| RF connectors | CNC machining (Brass) | Critical impedance control |
Surface Finish Comparison:
- Die casting: Ra 1.6–3.2μm (as-cast)
- CNC machining: Ra 0.4–1.6μm (with finishing)
2.3 Medical Devices
| Part Type | Recommended Process | Why? |
|---|---|---|
| Surgical instrument handles | CNC machining (Ti6Al4V) | Biocompatibility, precision |
| MRI housing | Sheet metal (SS 316L) | Non-magnetic requirements |
| Dental implant molds | Die casting (Zr alloy) | High detail replication |
Regulatory Note: CNC is preferred for FDA Class III devices due to better material traceability.
3. Cost Breakdown & Decision Factors
3.1 Cost Comparison Table (1000pcs Order)
| Process | Tooling Cost | Per-Unit Cost | Lead Time | MOQ |
|---|---|---|---|---|
| Sheet Metal | $1,200 | $4.80 | 2 weeks | 50 |
| Die Casting | $28,000 | $9.20 | 6 weeks | 1,000 |
| CNC Machining | $0 | $35.00 | 3 weeks | 1 |
Note: Based on aluminum parts 100×80×20mm in size
3.2 When to Choose Which Process?
Choose Sheet Metal If:
- Your part has uniform thickness
- You need fast prototyping
- Budget <$15,000
Choose Die Casting If:
- Annual volume >5,000pcs
- Complex 3D shapes required
- Surface finish is critical
Choose CNC Machining If:
- Tolerances <±0.05mm
- Material cannot be cast (e.g., titanium)
- Production volume <500pcs
4. Hybrid Approaches & Emerging Technologies
4.1 Combining Processes for Optimal Results
- Die Casting + CNC: For critical bore/hole tolerances
- Sheet Metal + Machining: Adding precision threads to brackets
- 3D Printing + CNC: Complex prototypes with finished surfaces
4.2 The Future: AI-Optimized Process Selection
Our proprietary Manufacturing Process Selector analyzes your CAD model to recommend:
✅ Most cost-effective method
✅ Potential DFM improvements
✅ Alternative material option
One Response
Why Partner With Us?
✔ All 3 Processes In-House: No subcontracting delays
✔ DFM Reports Within 24 Hours: Free with every quote
✔ Global Shipping: DDP terms available
Get Your Custom Cost Analysis: Upload drawings to receive:
Process recommendation
Side-by-side cost comparison
Lead time estimates