Titanium Grade 5 (Ti-6Al-4V) delivers 895-950 MPa tensile strength and about 828 MPa yield at a density of 4.43 g/cm³ — a strength-to-weight ratio that aluminium and stainless steel cannot match. SkillsProto holds ±0.005 mm on critical dimensions and ±0.05 mm as general tolerance, ships CNC titanium parts in 3-7 working days with a 48-hour expedite option, and accepts MOQ 1. A first article inspection report ships with every order, CMM data is available on request, and quotes with DFM feedback return within 24 working hours.
Grade 5 vs Grade 2 vs other titanium grades
Grade 5 is an alpha-beta alloy: 6% aluminium and 4% vanadium stabilise the two phases and push strength to roughly 2.7x that of commercially pure Grade 2. Grade 2 wins on corrosion resistance, formability and price. Grade 23 (Ti-6Al-4V ELI) sits in the same alloy family with tighter limits on interstitial elements and is normally specified for implants and cryogenic service rather than general engineering.
| Property | Grade 2 (commercially pure) | Grade 5 (Ti-6Al-4V) |
|---|---|---|
| Tensile strength | ~345 MPa | 895-950 MPa |
| Yield strength | Well below Grade 5, roughly 2.4x lower | ~828 MPa |
| Density | ~4.5 g/cm³ class | 4.43 g/cm³ |
| Hardness | Softer, lower Brinell | ~334 HB |
| Thermal conductivity | Low | ~6.7 W/m·K |
| Corrosion resistance | Excellent | Very good |
| Formability | Good | Limited, usually machined |
| Relative part cost | Lower | Higher, 5-10x the machining cost of aluminium |
| Typical applications | Chemical plant, marine hardware, heat exchangers | Aerospace brackets, motorsport, medical instruments, robotics joints |
Pick Grade 2 when the environment is the problem and the loads are modest. Pick Grade 5 when the part has to carry load at minimum weight, above roughly 300 °C, or inside the human body. SkillsProto machines both grades on the same equipment and will flag a downgrade to Grade 2 in the DFM feedback when the load case allows it.
Tolerances SkillsProto holds on titanium
| Feature type | Standard capability | Tight-tolerance capability |
|---|---|---|
| Linear dimensions | ±0.05 mm | ±0.005 mm |
| Bore diameters | ±0.02 mm | ±0.008 mm |
| Flatness | 0.05 mm / 100 mm | 0.02 mm / 100 mm |
| Positional tolerance of hole patterns | ±0.05 mm | ±0.01 mm |
| Surface roughness, as milled | Ra 1.6-3.2 µm | Ra 0.8 µm with finish passes |
Titanium is dimensionally stable once heat is controlled, so ±0.005 mm is repeatable on critical fits. SkillsProto applies it selectively: tight numbers on bores, datums and sealing faces, ±0.05 mm everywhere else, so the part does not pay for accuracy it does not need. Every first order ships with a first article inspection report; CMM measurement can be requested for hole patterns, flatness and profile callouts. DDP delivery to the UK, EU and US takes 3-5 days after the parts leave the machine shop.
Why titanium costs more
| Cost driver | Aluminium baseline | Grade 5 titanium | How SkillsProto limits it |
|---|---|---|---|
| Raw stock | 1x | Higher per kg, and buy-to-fly ratios are worse on plate stock | Near-net blanks and nested layouts |
| Machining cost | 1x | 5-10x | High-efficiency roughing, 5-axis single-setup finishing |
| Cycle time | 1x | Typically 2-4x longer | Constant radial engagement toolpaths, no dwell |
| Tool consumption | 1x | Several times higher, edges fail fast above 400 °C | Sharp dedicated inserts, scheduled replacement |
| Scrap risk | Low | High — a failed finish pass scraps expensive stock | Proven roughing allowance, in-process verification |
Thermal conductivity is the root cause. At ~6.7 W/m·K, Grade 5 moves heat away from the cut roughly four times slower than aluminium, so heat stays in the chip and in the tool edge instead of leaving with the workpiece. Slower cutting speeds, more passes and more tools follow directly from that physics, and the 5-10x machining cost is the result. Volume does not fix it: at 500 pieces the per-part price falls, but titanium still costs multiples of aluminium per part.
Machining approach
- Cutting speeds for Grade 5 typically run 30-60 m/min with carbide tooling, against 300-600 m/min for aluminium.
- Sharp, polished, positive-rake inserts only; a worn edge work-hardens the surface and destroys the next pass.
- Radial engagement kept at 10-20% of cutter diameter with constant-load toolpaths so the tool never rubs.
- Through-tool high-pressure coolant at the cutting edge, not flood from the side — heat and chip evacuation are the whole problem.
- Climb milling and peck drilling; deep holes are pecked to keep chips out of the flutes and temperatures down.
- Pocket depth limited to about 3x cutter diameter in Grade 5 to control heat and deflection.
- Symmetric stock removal on thin features, with stress-relief roughing before the finish pass on flatness-critical plates.
- No dwell, no rubbing, no light finishing cuts that generate heat without cutting.
Surface finishes and post-processing
| Finish | Typical result | Added lead time |
|---|---|---|
| As-milled | Ra 1.6-3.2 µm | 0 days |
| Bead blast | Matte uniform surface, Ra 1.2-2.0 µm | +1 day |
| Vibratory finishing | Ra 0.8-1.6 µm with edge break | +1-2 days |
| Hand polish | Ra 0.2-0.4 µm | +2-3 days |
| Anodising | Colour set by voltage, typically 10-80 V | +2-3 days |
| Laser marking | Permanent part ID, no dimensional change | +1 day |
| Passivation and precision cleaning | Removes surface iron and cutting residue | +1 day |
Anodising on titanium is a colour process controlled by voltage rather than a thick protective layer, so it adds no measurable thickness to mating dimensions. SkillsProto confirms finish sequencing in the quote so that critical tolerances are measured before, not after, cosmetic work.
Design rules
- Keep walls at 0.8-1.0 mm or more; 0.5 mm is possible on small, well-supported features only.
- Internal corner radius of at least 0.8 mm, ideally 1.5 mm, so the cutter does not stall in the corner and overheat.
- Limit pocket depth to 3-4x the cutter diameter; deep cavities in titanium drive cycle time up fast.
- Hole depth up to 5x diameter for holes above 3 mm, 3x diameter below that.
- Specify cut threads rather than formed threads, with engagement of at least 1.5x diameter, M2 minimum.
- Call out ±0.005 mm only on functional features; the rest of the drawing at ±0.05 mm keeps the quote down.
- Split thin plates into a symmetric roughing and finishing sequence when flatness matters.
- Consolidate multi-face parts into one 5-axis setup: fewer setups means fewer datum shifts and lower cost.
When to choose an alternative
| If the part needs | Better choice |
|---|---|
| Stiffness per dollar below 150 °C | 7075-T6 aluminium, far cheaper per part |
| High strength plus corrosion at 300 °C plus, or magnetic neutrality | 17-4PH stainless steel |
| Biocompatibility, or strength-to-weight above 300 °C | Grade 5 titanium |
| One or two cosmetic prototypes before committing to metal | 3D printing or vacuum casting |
| Thin-walled enclosure at 100-500 pieces | Sheet metal fabrication |
Grade 5 earns its price when weight, temperature or biocompatibility is the binding constraint. When it is not, SkillsProto will say so in the DFM feedback and quote the cheaper route alongside it.
Frequently Asked Questions
How much does titanium Grade 5 CNC machining cost compared with aluminium?
Machining Grade 5 typically runs 5-10x the cost of machining the same geometry in aluminium. The driver is thermal conductivity: at ~6.7 W/m·K the alloy holds heat at the cutting edge, which forces lower speeds, more passes and more frequent tool changes. Raw stock costs more per kilogram as well. SkillsProto quotes both materials on request so the delta is visible before the decision is made.
What tolerances can SkillsProto hold on Ti-6Al-4V?
±0.005 mm on critical dimensions and ±0.05 mm as a general tolerance, with bores at ±0.02 mm standard and ±0.008 mm tight. Flatness is held to 0.05 mm per 100 mm as standard and 0.02 mm per 100 mm on request. A first article inspection report ships with the order and CMM data can be requested for hole patterns and profile callouts.
How fast can SkillsProto ship titanium CNC parts?
Standard lead time is 3-7 working days from drawing approval, with a 48-hour expedite option for urgent work. MOQ is 1 piece. DDP shipping to the UK, EU and US adds 3-5 days, and quotes with DFM feedback are returned within 24 working hours.
Should I choose Grade 5 or Grade 2 titanium?
Choose Grade 5 when the part carries load at minimum weight: 895-950 MPa tensile and ~828 MPa yield against roughly 345 MPa for Grade 2. Choose Grade 2 when corrosion is the main enemy, when the part must be formed rather than machined, or when the load case allows a cheaper, softer material. Grade 2 is also easier to machine and costs less per part.
Does titanium need post-machining treatment?
Not structurally. Grade 5 forms its own oxide layer and resists corrosion as machined. Passivation and precision cleaning are recommended for medical and food-contact parts and add about 1 day. Bead blasting, polishing, anodising and laser marking are cosmetic or identification steps and add 1-3 days depending on the sequence.
Can I order a single titanium prototype?
Yes. MOQ is 1 piece, and the 3-7 working day lead time applies to single-part orders. For one-off visual prototypes, 3D printing or vacuum casting is usually faster and cheaper; SkillsProto quotes the CNC part and the alternative together when the geometry allows it.
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