Titanium Wire EDM for Aerospace and Medical Parts

Titanium erodes slowly on a wire EDM, noticeably slower than steel and far slower than aluminum, and that machine time is the main cost driver. The cause is titanium's thermal behavior: it has very low thermal conductivity (about 7 W/m-K for Ti-6Al-4V), so spark energy does not dissipate efficiently, and the erosion process per spark is less productive than on steel. Practically, a titanium cut can take 30-50% longer than the same thickness in steel. On top of the slow cut, fatigue-critical titanium parts usually require fine skim passes plus removal of the oxygen-enriched recast layer by chemical milling or etching, which adds secondary processing cost. Expect titanium wire EDM to run $130 to $250+ per shop hour, with per-part costs well above steel for equivalent geometry. The cost is justified when titanium's strength-to-weight or biocompatibility is required and the geometry is too intricate, thin, or hardened to mill economically. If the part is open and millable, get a milling quote first; titanium milling is also expensive but may still beat slow EDM on simple shapes.

Titanium is intensely reactive to oxygen at the temperatures EDM sparks generate, so the recast layer left on an EDM'd titanium surface is not just remelted metal, it is an oxygen-enriched, embrittled skin similar to the alpha case from machining titanium in air. This layer is hard, brittle, and prone to micro-cracking, and it significantly reduces fatigue life. For any titanium part that sees cyclic stress, aerospace structure, rotating components, and load-bearing implants, this layer should be removed. The standard process is to minimize it with fine skim passes (getting the recast down toward 0.0005 inch or less), then strip the embrittled surface by chemical milling, etching, or a light mechanical finish. Many aerospace specs mandate recast and alpha-layer removal on titanium EDM surfaces, often with NADCAP documentation. For a non-cyclically-loaded part like a static bracket or a fixture, the layer is usually acceptable as-is. The key is to state your fatigue and surface-integrity requirements when quoting so the shop routes the necessary skim passes and post-processing.

In the spark gap, Grade 23 and Grade 5 cut almost identically; both are Ti-6Al-4V and erode at similar rates with similar parameters. The difference is chemistry and what it implies for post-processing. Grade 23 is the ELI (extra low interstitials) version with tightly controlled low oxygen and iron, which gives it superior fracture toughness and ductility and makes it the preferred grade for surgical implants. Because Grade 23's whole value proposition is its clean, tough microstructure and biocompatibility, the oxygen-enriched recast layer EDM leaves behind is even more objectionable on it, you do not want to reintroduce an embrittled, oxygen-rich surface onto a high-purity implant alloy. So while the cut itself is the same, Grade 23 implant work almost always specifies fine skim passes and full recast/alpha-layer removal by chemical milling, plus passivation and ISO 13485 documentation. Grade 2, by contrast, is softer commercially pure titanium that erodes a bit more easily and is used where corrosion resistance and formability outrank strength. Always specify the exact grade and any surface-integrity requirement when you quote.

Yes, and that is one of the strongest reasons to choose EDM for titanium. Because wire EDM applies no cutting force, it produces thin walls, narrow slots, fine webs, and intricate profiles that would deflect, chatter, gall, or work-harden under a milling cutter or drill in titanium, which is exactly the kind of damage titanium is notorious for during conventional machining. Wire EDM routinely cuts titanium slots as narrow as the wire plus spark gap (roughly 0.008-0.012 inch with standard 0.010 inch wire, narrower with fine wire) and walls well under 0.010 inch. Tolerances of +/-0.0001 to +/-0.0002 inch are achievable with skim passes. This makes EDM the go-to for titanium aerospace brackets with delicate features, fluidic and instrument components, and intricate implant geometry. The tradeoffs remain the slow cut speed and the need to manage the oxygen-enriched recast layer on fatigue-critical surfaces. But for geometry that titanium milling simply cannot produce without distorting or destroying the feature, wire EDM is the answer.