Materials Machining Guide
Titanium Grade 5 (Ti-6Al-4V) Machining Guide — Feeds, Speeds, Fire Safety, Tools
Titanium doesn't like heat. It doesn't like light chip loads. It doesn't like dull inserts. Get any of those wrong and you cook a tool or scrap a part — and titanium chips can literally catch fire. This guide covers the specifics for machining Grade 5 (Ti-6Al-4V) for aerospace, defense, subsea, and specialty oil & gas applications.
Why titanium is hard
Three properties conspire against easy titanium machining. Low thermal conductivity: heat generated at the cutting edge stays there. High chemical reactivity at elevated temperature: titanium welds to cutting tools. Low modulus (~half of steel): parts flex under lighter loads than expected, causing chatter and tolerance issues.
The strategy: aggressive chip load to keep heat leaving with the chip; sharp coated carbide (or PCD for high volume); flood coolant generously; rigid setups; and chip evacuation planning.
Tooling
| Operation | Insert geometry | Substrate/Coating | Notes |
|---|---|---|---|
| Turning — roughing | Positive rake, chip-breaking | AlTiN or TiCN carbide | Aggressive feed; fresh insert per predefined tool life |
| Turning — finishing | Sharp positive edge | Fine-grain AlTiN carbide | PCD viable for high-volume runs |
| Milling — roughing | High-feed positive insert | AlTiN carbide | Trochoidal path; light axial DOC, high feed |
| Milling — finishing | Solid carbide end mill, sharp | AlTiN or diamond-like | Climb-mill; light DOC |
| Drilling | Solid carbide, through-coolant | AlTiN | Peck cycles; flood + through-tool essential |
Feeds and speeds
| Operation | SFM | Feed | Notes |
|---|---|---|---|
| Turning — roughing | 150–250 | 0.008–0.015 IPR | Aggressive chip load |
| Turning — finishing | 200–350 | 0.004–0.008 IPR | Sharp fresh insert |
| Milling — roughing | 150–250 | 0.003–0.006 IPT | Trochoidal; controlled radial DOC |
| Milling — finishing | 200–350 | 0.002–0.005 IPT | Climb-mill |
| Drilling | 50–100 | 0.004–0.010 IPR | Through-tool coolant essential |
Chip fire risk — real, not theoretical
Titanium chips are pyrophoric. Fine chips packed in a chip pan can ignite spontaneously in the presence of moisture or by friction. Chip pans need to be emptied regularly, especially on machines running titanium heavy. Have a Class D fire extinguisher (metal fires) on-hand, not water or CO2.
Best prevention: keep chips flowing off the machine, don't accumulate. High-pressure coolant is a friend here — it moves chips as they form. Water-based coolant reduces fire risk; oil-based coolant can enable fire under some conditions.
Common mistakes
- Light chip loads ("gentle" cutting) — Guarantees rapid tool failure. Heat stays in the cut instead of leaving with the chip.
- Dull inserts — Tool welds to workpiece; part scrapped; possible fire. Replace before dulling.
- Flimsy fixtures — Titanium's low modulus + chatter = scrapped tolerance. Rigid setups mandatory.
- Chip accumulation — Fire risk. Empty chip pans daily; more often on high-volume runs.
- Water-only coolant on deep drilling — Poor lubricity for titanium; use proper cutting fluid formulated for titanium.
Frequently asked questions
Where can I get Titanium Grade 5 CNC machined in Texas?
B&R Productions in New Waverly, TX runs Titanium Grade 5 weekly. Direct number for RFQs and rig-down work: (936) 291-7827. Serving Houston, Conroe, Huntsville, The Woodlands, Dallas, San Antonio, Austin, and the Gulf Coast.
What tolerance can be held on Titanium Grade 5?
±0.0005" routine on critical features with sharp coated carbide, controlled feeds and speeds, and CMM verification. Tighter possible with the right fixture and setup discipline.
What SFM should I run on Ti-6Al-4V?
Turning: 150–250 SFM for roughing, 200–350 for finishing. Milling: similar range. Aggressive feed (0.008–0.015 IPR turning) is critical — light feeds cause tool failure faster than high SFM does.
Can titanium chips really catch fire?
Yes — pyrophoric. Fine chips packed in chip pans can spontaneously ignite. Best prevention: keep chips flowing off the machine. Have a Class D metal-fire extinguisher on hand; don't use water, CO2, or standard ABC extinguishers on titanium fires.
What tolerance can be held on titanium?
±0.0005" routine on critical features. Rigid fixture setup is essential — titanium's low modulus makes part deflection a real tolerance risk without proper support.
Are PCD tools worth it for titanium?
For high-volume Grade 5 work, yes — extended tool life amortizes the tool cost. For prototype or small-batch runs, coated carbide (AlTiN) is more cost-effective.
What's the difference between Grade 5 and Grade 23?
Grade 23 (Ti-6Al-4V ELI, Extra Low Interstitial) has tighter chemistry limits than Grade 5 — used for medical and cryogenic applications where impurity levels matter. Machinability is nearly identical.
Does titanium work-harden like Inconel?
Less severely, but yes — under low-feed cutting or dwelling. Same prevention applies: aggressive feed, sharp tools, no dwelling.