CNC Titanium Parts Purchase Guide

A reliable CNC titanium order starts with a controlled definition of the part—not with “precision,” “aerospace grade,” “medical grade” or a machine list. The buyer and supplier need the same authority, revision, material, geometry, process, inspection, evidence and change-control basis.

1. Freeze Product-Definition Authority and Revision

List every controlling file and document: 3D model, 2D drawing, specification, purchase order, quality clause and approved deviation. State file names, revision levels, units and the precedence rule. If the model and drawing conflict, stop and resolve the conflict in writing.

“Model controls” does not automatically define tolerances, surface texture, threads, special characteristics or inspection reporting. “Drawing controls” does not excuse an unresolved mismatch with the supplied model.

2. Define Function, Service and Supply Scope

Describe what the component must do and where it interfaces with the assembly. Identify loads, temperature, media, pressure or vacuum, motion, electrical or thermal duty, sealing, wear, cleaning, maintenance and expected life only where they affect the part requirements.

• Mark functional surfaces, mating parts, assembly datums and no-touch areas.
• Define whether the order covers raw material, machining, secondary processes, cleaning, assembly, inspection, packing and documentation.
• Identify customer-supplied material, tooling, gauges or special instructions.
• Separate supplier review from the buyer's design and regulatory approval responsibility.

3. Control Titanium Grade, UNS, Raw Form and Condition

Specify the exact Grade or alloy, UNS when needed, governing material specification and revision, starting-material form and ordered condition. A commercial Grade name alone may not define product form, condition, test requirements or certificate content.

These references govern raw material within their scopes. They do not define the finished machined part, its GD&T, threads, surface, cleanliness or customer approval.

4. State the Standards Map and Contract Revision

Identify the standard used for each requirement and state the revision that the contract invokes. ASME Y14.5 establishes a dimensioning and tolerancing language for engineering drawings, models and related documents. ISO 1101 defines the symbol language and interpretation rules for geometrical specification. Select the system that the product definition requires; do not combine rules without an explicit, reviewed basis.

5. Build a Functional Datum Scheme and GD&T Plan

Datums should connect the part to its function, assembly and inspection setup. Mark datum features, order of precedence, basic dimensions, material-condition modifiers and feature-control frames clearly. Avoid using GD&T symbols as decoration or to compensate for an unstable datum strategy.

• Identify the surfaces or axes that locate the part in the assembly.
• Check that datum features are accessible and physically simulatable.
• Define profiles, position, runout, flatness, perpendicularity or other controls only where they express functional intent.
• Align the inspection plan with the governing standard, datum setup and reporting expectation.

6. Separate Design Tolerance from Manufacturing Capability

A tolerance is a product requirement. A process-capability claim is evidence about a process under stated conditions. Do not turn a supplier's best-case number into a blanket tolerance for every feature, material state, size and quantity.

If capability evidence is required, define the characteristic, part family, process state, sample size, statistic and acceptance rule. “Can hold ±0.005 mm” without this context is not a reliable purchasing statement.

7. Define Threads, Holes, Fits and Assembly Interfaces

Threads require the system and standard, nominal size, pitch, class or tolerance, handedness, full-thread depth, runout, lead-in, gauge method and any insert, locking or anti-galling requirement. For holes, define diameter, depth, positional control, countersink/counterbore, breakthrough, burr and inspection method.

• State the mating-part or fit requirement for shafts, pins, sleeves and bores.
• Identify sealing surfaces, O-ring grooves, valve seats and pressure boundaries.
• Define reference temperature or fit basis when it matters.
• Specify thread or plug/ring gauge requirements and report scope rather than “thread OK.”

8. Specify Surface Texture, Edge Condition and Cleanliness

Surface finish should identify the parameter, limit, direction/lay when relevant, evaluation method and applicable surface. A single “Ra” value does not describe every functional surface or defect limit.

9. Review Process Route, Setups, Workholding and Distortion

The route may include sawing, rough machining, stress management, turning, milling, drilling, threading, finish machining, deburring, cleaning and inspection. The supplier should review the actual geometry and quantity before confirming route and feasibility.

• Thin walls, deep pockets, slender shafts and large material removal may require staged machining and distortion control.
• Datum transfer between setups can affect positional relationships and runout.
• Workholding marks and clamp areas should be agreed when cosmetic or functional surfaces are involved.
• Five-axis or multi-axis equipment can reduce setups for some parts, but machine configuration alone does not prove finished-part capability.

10. Control Heat Treatment, Coating and Other External Processes

For every internal or subcontracted special or secondary process, name the specification, revision, approved-source requirement, lot link, certificate, test, change-control route and nonconformity responsibility.

11. Match Inspection to the Characteristic

Create an inspection plan that lists each critical characteristic, method, equipment, datum setup, sampling or 100% extent, acceptance rule and report format. A CMM may be appropriate for many dimensional and geometric characteristics, but not automatically for surface texture, thread form, internal defects, chemistry or every inaccessible feature.

First article and production release

• Define whether first article inspection is required, on which part and route, and in what report format.
• State whether ballooned drawings, raw data, capability studies, gauge R&R or retained samples are required.
• Define revalidation triggers after revision, source, material, program, tooling, fixture, machine, special-process or location changes.
• Distinguish first-article approval from ongoing lot acceptance.

12. Link Traceability, Documents and Change Control

Define the traceability chain from raw-material heat or lot through cut blank, work order, process lots, inspection status, part marking, packing list and release documents. State whether one-to-one, batch or shipment-level traceability is required.

• Create a document index: material certificate, process certificates, dimensional report, FAI, NDE/test reports, deviation approvals and certificate of conformance.
• Require written approval before changing material source, raw form, route, qualified processor, program, critical tooling or inspection method where qualification depends on it.
• Define handling of nonconformance, rework, repair, concession, retest and replacement.
• Do not treat ISO 9001, AS9100 or ISO 13485 certification as automatic finished-part approval; system certification and product acceptance are different controls.

13. Protect Critical Features During Packing and Delivery

Packaging should prevent damage, contamination, corrosion from incompatible contact materials, thread impact, loss of identification and mixing of revisions or lots. Identify caps, separators, clean bags, desiccant, orientation or custom supports only where required by the part and route.

• Protect threads, sharp/fragile edges, sealing faces, thin walls and finished bores.
• Segregate part numbers, revisions, lots and inspection status.
• Align part label, inner package, outer package, packing list and document index.
• State Incoterm, named place, delivery date basis and responsibility for export packaging.

14. Normalize Cost and Quotation Scope

Cost can be driven by raw-material form and buy-to-fly ratio, quantity, setup count, tool access, cycle time, thin-wall or distortion control, critical tolerances, threads, surface, secondary processes, inspection, documents, packaging and logistics. A design-for-manufacture review can identify options, but savings should not be promised before the controlled design is reviewed.

• Compare the same revision, material, raw form, quantity and finished scope.
• Separate one-time programming/tooling/fixture/FAI cost from recurring unit price where useful.
• Record MOQ driver, quotation validity, schedule assumptions, exclusions and approved alternatives.
• Make deviations visible beside the quoted requirement; do not bury them in general notes.

15. Complete CNC Titanium Parts Purchase Guard

15.1 Product-definition control

• List drawing, model, specifications, purchase-order clauses and revisions.
• State the authority and precedence rule.
• Resolve all conflicts and open characteristics in writing.
• Freeze approved deviations with the order package.

15.2 Material and starting stock

• State Grade/alloy, UNS, material specification and revision.
• Define bar, plate, forging or customer-specific starting form and condition.
• Set heat/lot traceability and certificate content.
• Prohibit substitutions without written approval.

15.3 Datums, GD&T and dimensions

• State ASME Y14.5, ISO 1101 or the required product-definition system and revision.
• Confirm functional datums and inspection setup.
• Separate critical controls from general tolerances.
• Define basic dimensions, material-condition modifiers and profile boundaries clearly.

15.4 Threads, holes and interfaces

• Define system, size, pitch, class, handedness, depth and runout.
• Specify holes, counterbores/countersinks, fits, grooves and sealing surfaces.
• Name gauges, inspection methods and reporting requirements.
• State inserts, locking, lubrication or anti-galling requirements where applicable.

15.5 Surface, edges and cleanliness

• Map texture parameters and limits to the affected surfaces.
• Define edge breaks, burr criteria and no-touch/cosmetic areas.
• Specify cleaning, prohibited residues, handling and verification.
• Protect surfaces through secondary processing and packing.

15.6 Manufacturing and external-process boundary

• Review setups, workholding, datum transfer, heat and distortion risk.
• List heat treatment, coating, NDE, cleaning or other controlled processes.
• Define approved sources, specifications, certificates and change control.
• State whether repair or rework requires buyer approval.

15.7 Inspection and first article

• For each critical characteristic, state method, equipment, extent, acceptance and report.
• Define FAI scope, format, approval authority and revalidation triggers.
• Include gauge calibration and measurement-system requirements where necessary.
• Do not assume a CMM covers threads, surface, material or every inaccessible feature.

15.8 Traceability and release documents

• Link raw-material heat/lot, work order, process lots, part marking and shipment.
• Agree the document index before quotation.
• Identify shipment/lot/part level for each result.
• Reject generic or unrelated certificates as order evidence.

15.9 Commercial and schedule basis

• Normalize quantity, currency, Incoterm and named place.
• Separate one-time and recurring charges where useful.
• Record material, programming, tooling, inspection, document and transit assumptions.
• Define events that reset price or schedule.

15.10 Packing and post-delivery control

• Protect critical surfaces, threads, bores, thin walls and part identity.
• Prevent lot/revision mixing and incompatible contact.
• Define storage, shelf-life or cleanliness controls if applicable.
• Agree claim evidence, containment, replacement and corrective-action expectations.

Red flags before purchase order

16. RFQ and Pre-Order Checklist

17. CNC Titanium Parts Purchasing FAQ

Standards References

• ASME Y14.5 — Dimensioning and Tolerancing
• ISO 1101:2017 — Geometrical tolerancing
• ASTM B348/B348M — Titanium and titanium-alloy bars and billets
• ASTM B381 — Titanium and titanium-alloy forgings