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CNC Machining vs DMLS/SLM: Complete Comparison for Titanium

Compare CNC machining vs Direct Metal Laser Sintering (DMLS) / Selective Laser Melting (SLM) for manufacturing titanium components. Geometry, tolerance, cost, lead time, and application recommendations.

CNC MachiningvsDMLS / SLM (Additive Manufacturing)

Quick Answer

Choose CNC machining for tight tolerances (±0.005 mm), larger part sizes (up to 2000 mm), lower per-unit cost at higher volumes, and established material properties. Choose DMLS/SLM for complex geometries (lattice structures, internal channels), low-volume production (1-20 pieces), and applications where material waste reduction and design freedom outweigh higher per-part cost.

Quick Answer

Choose CNC machining for parts requiring tight tolerances (±0.005 mm), larger sizes (up to 2000 mm), and cost-effective medium-to-high volume production. Choose DMLS/SLM for complex geometries impossible to machine (lattice structures, internal conformal channels), rapid prototypes (5-10 days), and applications where design freedom outweighs higher per-part cost.

Side-by-Side Comparison

Property CNC Machining DMLS / SLM
Process Type Subtractive (removes material) Additive (builds layer by layer)
Typical Tolerance ±0.005 mm (±0.0002“) ±0.1 mm (±0.004“)
Surface Finish (as-built) 0.4-1.6 µm Ra 6-10 µm Ra
Min Feature Size 0.5 mm 0.3-0.5 mm
Max Part Size 2000 x 1000 x 800 mm 250 x 250 x 300 mm
Geometry Freedom Limited by tool access Unlimited (lattices, internal channels)
Material Utilization 10-80% (chip waste) <5% waste (powder recycled)
Lead Time (prototype) 5-10 business days 5-10 business days
Setup Cost Moderate (fixturing) Low (build file only)

Mechanical Properties

Property CNC (Wrought Ti-6Al-4V) DMLS/SLM (as-built) DMLS/SLM + HIP
Ultimate Tensile 950 MPa 950-1050 MPa 950-1000 MPa
Yield Strength 880 MPa 850-950 MPa 850-900 MPa
Elongation 14% 8-12% 12-14%
Fatigue Strength ~500 MPa ~300-400 MPa ~450-500 MPa
Density 100% 99.5-99.9% 99.9+%

Cost Analysis

Volume CNC Machining DMLS / SLM
1-5 pieces $$ (setup cost dominant) $$ (no tooling)
10-50 pieces $$ $$$$
100+ pieces $ (amortized tooling) Not cost-effective
Material waste Significant (up to 70%) Minimal (<5%)

Lead Time Comparison

Stage CNC Machining DMLS / SLM
Setup/File Prep 1-2 days 1-2 days
Production (1-10 pcs) 5-10 days 5-7 days
Post-Processing Included Additional (support removal, HIP)
Total (simple part) 5-10 days 7-14 days

Choose CNC Machining When

  • Tight tolerances required (±0.005 mm or tighter)
  • Large part size (>250 mm in any dimension)
  • Simple to moderate geometry
  • Medium to high volumes (>20 pieces)
  • Critical surfaces need fine finish

Choose DMLS/SLM When

  • Complex internal geometries (cooling channels, lattices)
  • Weight reduction through topology optimization
  • Very low volumes (1-5 pieces) with complex design
  • Rapid iteration on design
  • Material waste is a cost driver

Selection Decision Framework

If tolerance < ±0.05 mm → CNC Machining
If internal channels or lattices → DMLS/SLM
If quantity > 20 → CNC Machining
If part size > 300 mm → CNC Machining
If design still iterating → DMLS/SLM
If surface finish < 1 µm Ra → CNC Machining
  • Knowledge: CNC Machining, Additive Manufacturing
  • Services: Titanium CNC Machining, Titanium Additive Manufacturing