Guide: High-performance machining of titanium alloys
Titanium alloys are indispensable in medical technology and aerospace due to their strength and corrosion resistance. Nevertheless, they are considered to be 10-15 times more difficult to machine than brass.
1. physical challenges
| The problem | Consequences | Solutions |
|---|---|---|
| Low thermal conductivity (only approx. 16% of steel) | 80% of the heat is concentrated at the cutting edge. | High pressure cooling (HPC) recommended; TiAlN-coated carbide. |
| Low modulus of elasticity (55% of steel) | "Springback" effect leads to dimensional deviations and flank wear. | Positive rake angles; high feed rate to reduce springback. |
| Chemical reactivity | Build-up cutting and wear of the tool; unstable process; poor surface quality. | Sharp cutting edges andTiAlN or AlTiSiN coating. |
| Work hardening | Notch wear; tool breakage during subsequent cuts. | Sharp cutting edges; Sufficient infeed (>0.10 mm if possible), no dwell times. |
| Long chips | Chip nests during internal turning or parting off | Chip breakers for internal turning tools and roughing cutters (e.g. Swiss-MicroTurn MTEP); ACP+, LFV, etc. for external turning; high-pressure cooling; trochoidal milling. |
2. recommendations according to machining type
Turning & external grooving
- Strategy: "Low speed, high feed". A thicker chip dissipates heat better.
- Parameters:Vc 40-90 m/min, f 0.08-0.20 mm/rev.
- Solution: Carbide K10-K20 with TiAlN coating (e.g. Tungaloy-NTK DM4).
Internal turning on Swiss-type automatic lathes
- Rigidity: Keep overhang from guide bush to a minimum (< 3 mm).
- Solution: Ifanger Swiss-MicroTurn cutting steels MTEP, MTEE, MTEC, MTKO and others with internal cooling (holder MTHA).
- Parameters: Vc 40 m/min, f 0.01-0.05 mm/rev.
CNC milling
- Strategy: Trochoidal milling paths
( Ae 5-15%) for constant temperature control. - Entry: Arc-shaped tool entry to avoid force peaks.
- Requirements: Internal cooling with 100-150 bar; corner radius; chip breaker; low cutting speed Vc
- Solution: Maykestag Speedcut 4.0 Titanium, specially developed for titanium alloys.
CNC drilling
- Challenge: "Drilling into rubber" effect and chip jam at depths >3xD.
- Solution: Ifanger Swiss-Drill ISDTA803 for drill holes 0.30<Ø<1.00 mm
- Parameters: Vc 12 m/min, f 0.007-0.015 mm/rev.
Professional tip: Use a pilot drill when drilling alloys from 6xD to guarantee process reliability and avoid drill breakage.
Knurling
- Process: Prefer cutting knurling (cut knurling) to reduce contact pressure forces by 40%.
- Solution: Ifanger Swiss-Knurl system with DVA-coated HSS wheels or carbide rollers (>60 HRC).
3. classification of titanium alloys
| Group | properties | Machinability index (steel=100%) |
|---|---|---|
| Alpha alloys (grades 1-4) | Pure titanium, not heat treatable, extremely corrosion resistant. | 35-46% |
| Alpha-beta alloys (e.g. grade 5) | Ti-6Al-4V: The "workhorse" of the industry (~50% market share). TiZr with a Zr content of 15%-20% also belongs to the alpha-beta family. | 18-28% |
| Alpha-Beta alloy Grade 23 "ELI" | Reduced =2 content, improved toughness for implants. | 18-28% |
| Beta alloys (e.g. Ti-10V-2Fe-3Al) | Highest strength (up to 1,400 MPa), extremely difficult to machine. | 15-20% |