Titanium Alloys CNC Machining, Reviewed Before Production

Commercially Pure And Alpha

Grades 1–4 are commercially pure alpha titanium; oxygen raises strength while reducing formability.

Ti-5Al-2.5Sn is alpha titanium: aluminum strengthens it, weldability is good, and heat treatment gives little strengthening.

Near-Alpha And Alpha-Beta

Near-alpha alloys use aluminum plus tin or zirconium for elevated-temperature strength and creep resistance.

Ti-6Al-4V, Grade 5, is alpha-beta: aluminum stabilizes alpha and vanadium beta; it responds to heat treatment and suits high-strength structural parts.

Beta Titanium Alloys

Beta alloys retain more body-centered-cubic beta phase through molybdenum, vanadium, chromium, or iron additions.

Beta grades offer highest heat-treatable strength and useful cold formability, but weld procedure qualification remains material- and section-dependent.

Specify The Complete Callout

ASTM B348 covers bar and billet; ASTM B265 covers plate and sheet. State AMS, ASTM, EN, or customer specification revision, condition, dimensions, permissible substitutions, and certificate level.

Grade 23 is not interchangeable with Grade 5 when low-interstitial chemistry or application controls apply. Identify heat treatment before machining and whether post-machining stress relief is required.

Match Form To Geometry

Bar favors turned shafts, pins, and rotational parts; plate favors prismatic cavities and inserts. Tube can reduce bored-out waste, while wire suits EDM stock or formed products rather than bulk machining.

Forgings and near-net preforms can preserve directional grain flow and reduce chip volume, but require verified allowance, datum access, and machining envelope.

Form Selection Comparison

Material availability changes with grade, diameter, thickness, and certification demand. Confirm mill lead time and actual stock size before freezing a costed route.

Select The Surface Route

Three common routes are as-machined, bead-blasted, and polished. Each can change appearance, handling, and mating behavior, so call out the applicable faces and surface-texture requirement.

Critical bores, datums, threads, and sealing faces need masking or a defined post-finish operation when fit is affected.

Mark For Traceability

Laser marking can identify part number, revision, lot, or serial number without treating the mark as decoration. Define content, location, character height, contrast expectation, and prohibited surfaces on the drawing.

Anodic color may aid visual identification, but its suitability requires validation against corrosion, cleanliness, fit, and application-specific regulatory requirements.

Protect Finished Parts

Protective packaging should prevent metal-to-metal contact, abrasion, and mix-ups during shipment. Request individual separation for cosmetic or critical surfaces and link labels to the purchase-order revision and inspection records.

Cleaning or passivation requests should name the governing specification, residue limits, and verification evidence required for the application.

Access And Rigidity

Three-axis reach, tool overhang, and workholding stiffness should be reviewed together; deep pockets and long slender walls can deflect during cutting. Specify minimum wall thickness only after the part geometry, stock condition, and fixture approach are assessed.

Internal radii should suit available cutter diameters, while inaccessible corners may require EDM or a design change. Critical mating faces need a datum scheme that supports both machining setup and measurement.

Heat, Chips, And Edges

Continuous engagement can concentrate heat at the cutting edge, so toolpath strategy, coolant delivery, and chip evacuation belong in the manufacturing review. Thin webs and asymmetric stock removal deserve attention because released stress can move the part.

Threads, cross-holes, sharp intersections, and small slots require explicit deburr requirements. State whether edge breaks are permitted, their size range, and any surfaces where burrs cannot remain.

Inspection Evidence

100% inspection is not automatically necessary; the drawing should identify critical dimensions, datums, surface-roughness limits, and reporting requirements. Request the inspection method and sampling plan before release, especially for features measured after unclamping.

First-article records should link measured results to the current drawing revision and material documentation required by the order. For distortion-sensitive parts, discuss inspection state, support method, and any post-machining stress-relief sequence early.

• Current drawing revision and ballooned report
• Material and heat-treatment documentation, when specified
• Dimensional results tied to declared datums
• Surface-finish and thread verification method

Verify Material Evidence

One heat or lot number should link incoming stock to the part traveler and final records.

Two documents matter at minimum: the material certificate and the revision-controlled purchase specification.

• Confirm grade, product form, and heat-treatment condition.
• Define required traceability before cutting stock.

Test The Process Route

Three questions expose useful scope: can tools reach critical features, is EDM necessary, and is grinding stock defined?

One DFM response should identify datum conflicts, thin-wall risk, workholding, and inspection access before release.

• Request comparable geometry, not generic capability lists.
• Review CNC, EDM, grinding, and fitting as one route.

Control Approval And Delivery

First-article approval should state ballooned dimensions, measurement methods, acceptance criteria, and approved revision.

Each shipment needs protected packaging, visible part identification, and documents matched to the purchase order.

• Set report format and sampling plan.
• Agree change notification and lead-time milestones.
• Confirm packaging for surface-sensitive features.

Specify Material Completely

Grade 5 alone is incomplete: require the applicable ASTM or AMS standard, mill form, condition, and heat-treatment state.

Grade 23 is not interchangeable with Grade 5: chemistry limits, application requirements, and documentation can differ. Provide approved material substitutions and required traceability.

Match Tolerances To Function

0.01 mm on every dimension can add grinding, inspection, and cost without improving assembly performance. Identify CTQ dimensions, datums, mating interfaces, and allowable geometric variation.

Ra values and cosmetic expectations need definition before routing. State surface roughness, finish direction, edge-break limits, and areas where tooling marks are unacceptable.

Align Interfaces And Evidence

Two dissimilar metals in a wet assembly can create galvanic-corrosion risk. Supply mating materials, environment, isolation method, fastening load, and coating restrictions.

Day 1 is the correct time to request certificates and reports. Compare quotations only after confirming equivalent material evidence, machining route, inspection scope, quantity, packaging, and delivery terms.

Release The Technical Package

Two files should travel together: a dimensioned 2D drawing and the matching native or neutral 3D CAD model. Identify material grade, product form, governing specification, heat treatment, and any acceptable equivalent.

Each revision should carry a unique revision identifier and release date. Mark datums, threads, edge breaks, surface finish, and features that cannot be changed without written approval.

Define Critical Requirements

Three requirement groups deserve explicit callouts: critical-to-quality dimensions, functional surfaces, and inspection method. State the allowable tolerance, datum reference, surface condition, and whether a report is required.

For titanium alloys, distinguish cosmetic finish from contact, sealing, or fatigue-relevant surfaces. Include mating-part information where fit or tolerance stack depends on it.

Close The First-Article Loop

Before ordering, request DFM feedback covering tool access, workholding, machining allowance, EDM or grinding needs, and inspection approach. Align the quotation with those assumptions, quantity, supplied material condition, and delivery milestone.

After first-article approval, freeze the drawing revision, CAD model, material evidence, and acceptance record. Route every later change through written revision control before repeat production.