티타늄 CNC 가공: 2026 가이드 (Grade 2, Grade 5, ELI)

When titanium is worth the premium

Titanium costs 8–10× aluminium and machines 5× slower — so it's only the right choice when its specific properties are non-negotiable. The five legitimate reasons to spec titanium:

• Strength-to-weight — Ti-6Al-4V yields at 895 MPa with density 4.43 g/cm³. Aluminium 7075 yields at 503 MPa with density 2.81 g/cm³. Titanium wins on strength-per-volume; aluminium wins on weight when strength margin allows.
• Biocompatibility — Titanium oxide is inert to body fluids. The standard for orthopaedic implants, dental implants, surgical instruments contacting tissue.
• Saltwater corrosion — Genuinely immune. Used in marine fittings, desalination plants, offshore oil tools.
• High-temperature service — Useful service to 400–500°C without losing strength. Aerospace hot-section parts, jet engine components.
• Non-magnetic + low thermal expansion — MRI-safe medical devices, precision optical mounts, satellite hardware.

Grade comparison

Why titanium is genuinely hard to machine

Titanium has three properties that make it the hardest common engineering metal to cut:

• Low thermal conductivity — Heat from cutting can't flow into the chip and away. Instead, it concentrates at the cutting edge, accelerating tool wear.
• Reactive at high temperature — Titanium chemically reacts with most cutting tool materials at the cutting-zone temperatures. Specific tool grades + coatings are mandatory.
• Springs back during cutting — Low elastic modulus (110 GPa, half of steel) means the workpiece deflects under cutter pressure, then springs back, causing rubbing and work hardening.

Practical implications for the cost and lead time of titanium parts:

Achievable tolerances on titanium

For tighter than ±0.013 mm on titanium, JLYPT uses 5-axis cells with thermal-stable fixturing and CMM verification of every part. Aerospace work routinely achieves ±0.005 mm with careful programming. See our tolerances guide.

Finishes for titanium

• As-machined + deburr — bare titanium has natural oxide protection.
• Bead blasted — uniform matte; standard for aerospace cosmetic.
• Type II / Type III anodise — yes, titanium anodises! Different from aluminium (no aluminium oxide layer). Produces colour through optical interference: gold, blue, purple, green, no dye needed.
• Electropolished — for medical implants; smooth, biocompatible surface.
• Passivation — citric or nitric acid bath, removes embedded contaminants from machining (mandatory for medical).
• PVD coating — DLC or TiAlN for wear surfaces, knife blades, bearings.
• Plasma electrolytic oxidation (PEO) — thick ceramic coating for extreme wear; used in some aerospace applications.

Industry applications

• Aerospace — Structural brackets, landing gear, fuel system, hot-section blades. Ti-6Al-4V is the workhorse; Ti-6242 for hot work. See aerospace manufacturing.
• Medical implants — Hip and knee replacements, spinal cages, dental implants, bone screws. Ti-6Al-4V ELI required for permanent implants.
• Surgical instruments — Forceps, retractors, cautery tips. Often CP Grade 4 for cutting edges, Grade 5 for handles.
• Marine & offshore — Pump shafts, propeller shafts, desalination components. CP Grade 2 dominates.
• Motorsport — F1 connecting rods, suspension uprights, exhaust valves. Ti-6Al-4V for strength-to-weight.
• Bicycle frames — Premium road and mountain bikes use Ti-3Al-2.5V (Grade 9) tubing for ride feel.
• Chemical processing — Reactor internals, heat exchangers, valve bodies in chloride or acidic environments. CP Grade 2.
• Jewellery — Hypoallergenic for sensitive skin; anodising creates iridescent colours without dyes.

Real cost (and how to manage it)

Titanium parts are expensive — there's no way around it. Here's realistic pricing for a 50×50×25 mm aerospace bracket:

Design tips that save real money on titanium

1. Use CP Grade 2 when strength allows — 30% cheaper than Grade 5, easier to machine.
2. Larger internal corner radii (≥ 1.5 mm) — lets us use bigger end mills, reducing cycle time 20–30%.
3. Avoid pockets > 3× tool diameter deep — titanium chatters at depth, requires slow finishing.
4. Symmetric material removal — minimises distortion from residual stress.
5. Allow stress-relief cycles for thick plates — rough → age → finish prevents post-machining warpage.
6. Don't over-tolerance — ±0.025 mm default is fine for most features. ±0.005 mm doubles cost.
7. Specify standard bar stock — Ti-6Al-4V comes in 12.7, 19, 25.4, 38, 50.8 mm rounds; choose the smallest fit.
8. For implants: specify Grade 23 (ELI) explicitly with ASTM F136 reference.
9. For aerospace: specify AMS-grade material (AMS 4928 for Ti-6Al-4V annealed bar).
10. Plan inspection in the design — CMM probe access on critical features avoids tear-down.