Choosing an Aerospace Machine Shop

Selecting a machine shop for defense and aerospace work is not just about who has the right equipment. It is about finding a supplier whose quality system, process discipline, and documentation capability match the demands of regulated manufacturing—and whose capacity and communication style can support your program timeline without creating downstream risk.

This guide is written for engineers and procurement professionals who need to evaluate and qualify machine shops that sit inside a broader regulated workflow that may include additive manufacturing (AM) (e.g., powder bed fusion (PBF), DMLS/SLM), Hot Isostatic Pressing (HIP) or PM-HIP consolidation, CNC machining, and tightly defined inspection and certification packs.

Certifications that matter

Certifications are a starting point, not an endpoint. They tell you that a shop’s quality management system has been audited against a recognized standard, but they do not tell you whether the shop can actually run your part reliably. Still, in aerospace and defense, certain certifications are table-stakes requirements that you should verify before investing time in a deeper evaluation.

AS9100
AS9100 is the aerospace quality management system standard built on ISO 9001 with additional requirements for risk management, configuration control, product safety, and counterfeit parts prevention. For most defense and aerospace machining work, AS9100 registration is a baseline expectation. Verify the shop’s current registration status through OASIS (the Online Aerospace Supplier Information System) or equivalent database.

What AS9100 tells you: The shop has a documented quality system, performs internal audits, manages nonconformances, and maintains calibration and traceability programs. What it does not tell you: whether the shop can hold your tolerances, manage your alloy, or deliver on schedule.

NADCAP
NADCAP (National Aerospace and Defense Contractors Accreditation Program) accredits specific special processes: heat treatment, chemical processing (plating, anodizing, passivation), nondestructive testing (NDE), welding, shot peening, and others. If your part requires any of these processes, confirm whether the shop performs them in-house under NADCAP accreditation or subcontracts to an accredited processor.

ITAR registration
If the work involves defense articles or technical data controlled under the International Traffic in Arms Regulations (ITAR), the shop must be registered with the Directorate of Defense Trade Controls (DDTC). This is a legal requirement, not optional. Verify registration and confirm the shop’s procedures for controlling access to ITAR technical data (drawings, models, specs) in both physical and digital form.

DFARS compliance
Defense Federal Acquisition Regulation Supplement (DFARS) clauses can flow down through the supply chain and include requirements such as specialty metals restrictions, country-of-origin controls, and cybersecurity obligations (including CMMC where applicable). Confirm that the shop is willing to accept and comply with the specific DFARS clauses in your PO and that they have a documented process for verifying and flowing down these requirements to their own suppliers.

Other certifications to check (as applicable)

• ISO 13485 for medical device machining (if the shop serves dual markets).
• Customer-specific approvals (e.g., approved supplier lists for specific primes or programs).
• Facility clearances for classified work, if applicable.

Capacity and capability assessment

Certifications confirm that the quality system exists. Capacity and capability determine whether the shop can actually execute your work—on time, in tolerance, and with the right documentation.

Equipment and process capability

• Machine types and axes: Confirm 3-axis, 4-axis, and 5-axis CNC milling, turning, and mill-turn capability. For complex aerospace geometry—especially AM or PM-HIP preforms—multi-axis machining is often necessary to reduce setups and maintain positional accuracy across features.
• Workholding and fixturing: Ask whether the shop designs and fabricates custom fixtures in-house. For irregular AM geometry, standard vise-and-parallels approaches often fail; the shop needs experience with soft jaws, vacuum chucks, conformal fixtures, or sacrificial features for stable workholding.
• Probing and in-process verification: Does the shop use on-machine probing for datum pickup, in-process checks, and tool-length compensation? For tight-tolerance parts, in-process verification reduces scrap risk and supports SPC data collection.
• Programming and simulation: Modern aerospace machining often requires 5-axis toolpath programming with collision checking and simulation. Ask what CAM system(s) the shop uses and whether they can import your CAD model format directly.

Alloy experience

Not all machine shops handle all alloys equally. Titanium, Inconel, refractory metals (tungsten, molybdenum, tantalum), and hardened steels each require specific tooling, speeds/feeds, coolant strategies, and chip management approaches. Ask for examples of similar alloys and geometries the shop has machined successfully, and whether they have documented process parameters for your material.

Inspection capability

• CMM (Coordinate Measuring Machine): Temperature-controlled inspection, probing access for complex features, and the ability to program and report against GD&T datums per the drawing. Ask about calibration status and whether CMM programs are revision-controlled.
• Surface metrology: Profilometers for Ra/Rz verification, optical inspection, and any specialized measurement for thin walls or lattice regions.
• NDE capability: If the part requires penetrant testing (PT), ultrasonic (UT), or other NDE after machining, confirm whether the shop performs it in-house or subcontracts. If subcontracted, verify the processor’s NADCAP status and how documentation flows back to the cert pack.

Capacity and scheduling

• Current load and lead time: Ask the shop for a realistic lead time estimate, not just a best-case number. Shops under heavy load may quote optimistic dates to win work, leading to schedule slips later.
• Dedicated vs shared capacity: For production runs, understand whether your work will be scheduled on dedicated machines or mixed in with other jobs. Dedicated capacity reduces variability; shared capacity can create scheduling conflicts.
• Scalability: If your program moves from prototype to production, can the shop scale? Do they have enough machines, operators, and inspection bandwidth to support increased volume without quality degradation?

Quality indicators beyond the certificate

The best way to assess a shop’s quality discipline is to look beyond the certificate and ask questions that reveal how they actually operate day-to-day.

Traveler and routing control
Ask to see a sample traveler (router). A well-controlled traveler shows each operation, the machine/program used, inspection hold points, and sign-offs at each step. It should be revision-controlled and traceable to the drawing revision. If the shop cannot produce a sample traveler quickly, their process control may be informal.

Tool management and change control
For precision aerospace work, tooling matters. Does the shop track tool life, manage tool changes based on wear data, and document which tool families are qualified for each material? Ad hoc tool management increases variability and scrap risk, especially in titanium and nickel alloys.

Nonconformance management
Ask how the shop handles nonconformances: Do they have a formal MRB (Material Review Board) process? How are deviations documented and dispositioned? Can they provide a corrective action example? A mature shop will have clear NCR (Nonconformance Report) and CAPA (Corrective and Preventive Action) processes under their AS9100 system.

First Article Inspection (FAI) capability
If your program requires AS9102-format FAI, confirm that the shop has experience producing complete FAI packages: ballooned drawings, measurement data for every characteristic, material cert references, and process documentation. Inexperienced shops often underestimate the effort and documentation rigor required for a compliant FAI.

Traceability discipline
For defense/aerospace parts, traceability from raw material to finished part must be unbroken. Ask how the shop maintains lot/serial identity through machining operations, especially when parts are batched, re-fixtured, or moved between machines. For AM parts entering the machining workflow, traceability should extend back to the build ID and powder lot.

Handling and packaging
Machined aerospace parts can be damaged by careless handling, poor inter-operation storage, or inadequate packaging for shipment. Ask about handling procedures for sensitive surfaces (anodized, peened, polished), how parts are protected between operations, and whether final packaging prevents mix-ups and handling damage.

5-axis vs 3-axis suitability

“Do you have 5-axis?” is a common question, but the better question is: does your part require 5-axis, and does the shop use it effectively?

When 5-axis matters:

• Complex contoured surfaces that cannot be reached in a single 3-axis setup without re-fixturing.
• Features on multiple faces or at compound angles that need to be machined in one setup to maintain positional accuracy.
• AM and PM-HIP preforms with irregular as-built or as-consolidated geometry that requires adaptive fixturing and multi-angle access.
• Thin-wall or low-rigidity parts where minimizing setups reduces deflection, distortion, and accumulated error.

When 3-axis is sufficient:

• Prismatic parts with features on a limited number of faces.
• Turned parts with simple milled features (mill-turn or 4-axis lathe may be adequate).
• Parts where tolerance is driven by a single datum and features do not span compound angles.

What to verify: Having a 5-axis machine is not the same as being proficient at 5-axis machining. Ask for examples of 5-axis work in similar materials, whether the shop programs and simulates 5-axis toolpaths in-house, and how they manage collision risk, tool access, and probing on complex setups.

Lead time and communication

Lead time is where many supplier relationships succeed or fail. In aerospace, schedule slips can cascade through assembly, test, and delivery milestones. A shop that communicates honestly about capacity and risks is more valuable than one that promises aggressive dates and misses them.

What to ask in an RFQ to get a truthful lead time

• Current shop load: Where is the shop in terms of capacity utilization? Are they quoting you into an already-full schedule?
• Material procurement: If the shop is sourcing material, what is the expected lead time for the specific alloy and form? For AM and PM-HIP preforms, who provides the preform and on what timeline?
• Outside processing: If heat treat, plating, NDE, or other steps are subcontracted, what is the lead time for each, and does the shop manage that scheduling?
• Programming and fixturing NRE: For first articles, how much time does programming, fixture design, and setup require? Is this included in the quoted lead time?
• Inspection and documentation: FAI, CMM reporting, and cert pack assembly can add days or weeks. Ensure these are included in the schedule, not treated as an afterthought.

Communication expectations

• Single point of contact: Is there a dedicated project manager or account contact? Or will you be chasing updates through a general inbox?
• Milestone updates: Will the shop provide proactive updates at key milestones (material receipt, first-op complete, inspection, ship), or only respond when you ask?
• Risk escalation: How does the shop communicate problems? A good shop raises issues early (tool breakage, material nonconformance, schedule conflict) rather than absorbing risk and hoping it resolves.

Evaluating a shop for AM and PM-HIP post-processing

If the machine shop is receiving AM or PM-HIP preforms rather than starting from billet or bar, the evaluation should include additional criteria specific to these workflows.

Experience with as-built AM surfaces
AM preforms have rough, irregular surfaces with partially sintered particles. Machining these surfaces requires appropriate tooling, entry strategies, and awareness of where supports were attached. Ask whether the shop has machined PBF or EBM preforms before and how they handle datum pickup on non-machined (as-built) surfaces.

Datum transfer from AM to machined condition
Establishing datums on an AM preform is different from starting with a clean billet. The shop should understand how to use probing, best-fit alignment, or sacrificial features to transition from as-built geometry to the drawing datum scheme. This is especially critical for parts that were HIPed (which may have changed dimensions) before machining.

Machining stock awareness
AM and PM-HIP parts come with designed-in machining stock on critical surfaces. The shop should verify that sufficient stock exists before committing to the finish machining plan. If HIP or heat treatment caused unexpected distortion, the shop should communicate this early rather than discovering it during finishing.

Integration with upstream and downstream processes
A machine shop that understands its place in the AM workflow—after stress relief, support removal, HIP, and heat treatment, but before final NDE and certification—can plan more effectively and avoid creating problems for downstream inspection. Ask how the shop coordinates with the AM supplier and with any outside processors (NDE, coating, etc.) in the chain.

Documentation compatibility
The cert pack for an AM + HIP + machined part requires coordinated documentation from multiple process steps. The machine shop’s contribution (machining traveler, CMM report, any in-process NDE) must integrate cleanly with the upstream records (build log, powder cert, HIP record, heat treat record). Confirm that the shop understands the documentation requirements and can produce reports that reference the correct part serial, build ID, and drawing revision.

RFQ and supplier qualification checklist

Use this checklist when evaluating a new machine shop for aerospace and defense work:

Certifications and compliance

• AS9100 registered (verify via OASIS)?
• ITAR registered with DDTC?
• Willing to accept DFARS clauses per your PO?
• NADCAP-accredited for any in-house special processes?
• Approved on your (or your customer’s) supplier list?

Equipment and capability

• Machine types (3-axis, 5-axis, turning, mill-turn) appropriate for your part?
• Experience with your alloy (titanium, Inconel, refractory metals, aluminum, etc.)?
• Custom fixturing capability (in-house design and fabrication)?
• On-machine probing and in-process verification?
• CMM inspection with GD&T reporting capability?
• NDE capability (in-house or approved subcontractor)?

Quality and documentation

• Can produce AS9102 FAI packages?
• Controlled travelers/routers with operation sign-offs?
• Formal MRB/NCR/CAPA process?
• Material and process traceability from raw material to finished part?
• Cert pack assembly experience (CoC, material certs, special process certs, inspection reports)?

Capacity and communication

• Realistic lead time for your part complexity and lot size?
• Scalable capacity from prototype through production?
• Dedicated point of contact?
• Proactive milestone and risk communication?

AM/PM-HIP integration (if applicable)

• Experience machining AM or PM-HIP preforms?
• Datum transfer and probing strategy for irregular geometry?
• Machining stock verification before committing to finish passes?
• Documentation compatibility with upstream AM/HIP records?

Choosing the right machine shop is a supply chain decision with direct impact on part quality, schedule, and program risk. The shops that perform best in aerospace and defense are not necessarily the largest or most automated—they are the ones with disciplined quality systems, transparent communication, and the technical depth to handle the alloys, tolerances, and documentation your program demands.

Explore Our Capabilities

Learn more about how Metal Powder Supply supports aerospace and defense manufacturing:

• Additive Manufacturing
• CNC Machining & Finishing
• Titanium Powder

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