CNC Machining Service for Aerospace Industry

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  What matters before you send an RFQ
• 2
  How to score an aerospace CNC supplier
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  What tolerance numbers actually mean on an aerospace drawing
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  When 5-axis machining is the right call, and when it is not
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  Aerospace material grades and the machining issues they bring
• 6
  Certifications, inspection, and what a paper trail should contain
• 7
  Lead time, order size, and confidentiality terms to check
• 8
  How to qualify a supplier in six steps

A shop that advertises ±0.005 mm is not promising that every feature lands there. The number describes what the process can hold on a well-supported feature with a rigid setup and a stable material. A thin wall, a deep pocket, or a long cantilever will move more than that no matter who cuts it. Send the drawing and ask which features the shop considers critical. The answer tells you whether they read it or just priced it.

Aerospace work usually concentrates tolerance on hole-to-hole relationships rather than on individual dimensions. True position, perpendicularity, and concentricity drive the fixture design more than any single size callout. If the shop quotes before discussing datum structure, expect a first article that needs rework. A useful DFM note will flag which datums are hard to reach in one setup and suggest an alternate scheme.

Surface finish interacts with tolerance in ways that are easy to miss. A bore held to ±0.005 mm with a Ra 3.2 μm finish will not seal the way the same bore with Ra 0.8 μm will. The finish range used here is Ra 0.2–0.8 μm for fine work, Ra 0.8–1.6 μm for general high-quality surfaces, and Ra 1.6–3.2 μm as machined. Match the callout to the function, not to habit.

Material choice changes the achievable tolerance as much as the machine does. Aluminum 6061 and 7075 cut cleanly and hold size well. Titanium Ti-6Al-4V and Inconel move under heat and work-harden at the cut, so the shop needs slower passes, more coolant, and often a stress-relief step between roughing and finishing. Ask how they handle that sequence.

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  Send the full drawingA STEP file alone hides datums, finish callouts, and notes that change the price.
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  Name the critical featuresThree or four dimensions matter more than the rest. Say which ones.
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  Ask about setup countEach re-fixture adds stack-up error, especially on thin-wall parts.

Five-axis work earns its cost when a part has features on multiple faces that must stay in relation to each other, or when the geometry has compound angles that would need custom fixturing on a 3-axis machine. A single 5-axis cycle removes the repositioning error between setups. On a bracket with four angled faces and a true-position callout across them, that difference is often the whole quality problem.

Five-axis also lets the shop use shorter, stiffer tools at an optimized angle. On superalloys like Inconel, that means less chatter, lower cutting forces, and longer tool life. The benefit is real but it is not free: cycle time is usually longer than a 3-axis roughing pass, and programming takes more engineering hours. For a simple prismatic plate with holes on one face, 3-axis is faster and cheaper and there is no quality gain from anything else.

The practical question is whether your part has a datum that crosses faces. If yes, ask for a 5-axis setup. If the part is flat, or if the tight features all sit on one face, 3-axis or 4-axis is the sensible choice. A supplier who pushes 5-axis on a flat plate is selling capability you do not need.

Capacity matters as much as capability. A shop with one 5-axis center cannot absorb a schedule slip. This plant runs 127 high-precision CNC machines, including 16 simultaneous 5-axis machining centers, 12 four-axis mills, 27 three-axis machines, and 16 mill-turn centers. That spread lets the shop match the machine to the part instead of forcing every job through the same spindle.

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  Use 5-axis for cross-face datumsCompound angles and true position spanning faces justify the setup.
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  Stay on 3-axis for flat platesOne-face features do not benefit from simultaneous motion.
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  Ask about spindle hoursCapability without open capacity adds weeks to your schedule.

Aluminum covers most airframe brackets, housings, and panels. The common grades are 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075, and ADC12 for castings. 7075 gives the best strength-to-weight but is less weldable and more prone to stress cracking at sharp internal corners. If a design has a tight internal radius in 7075, expect a tool-life and cracking conversation before the first cut.

Stainless grades appear in fittings, fasteners, and fluid components. The list here includes 303, 304, 316, 316L, 420, 430, 431, 440C, and 17-4PH (SUS630). 303 machines easily but has lower corrosion resistance. 316L and 17-4PH are chosen for corrosion and strength, and both work-harden, so the shop must keep the tool engaged and avoid dwelling in the cut.

Steel grades such as 1018, 1045, 4130, 4140, 4340, A36, and tool steel cover structural and high-load parts. 4130 and 4340 are common in aerospace structures because they take heat treatment well, but they need a thermal step between roughing and finishing to avoid distortion after machining.

Titanium and nickel alloys are where the cost sits. TA1, TA2, TC4 (Ti-6Al-4V), Inconel, and magnesium AZ31B or AZ91D all demand slow speeds, high coolant pressure, and sharp tooling. These alloys also carry the highest risk of subsurface damage, so the finishing pass matters more than the roughing pass for fatigue life.

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  Match grade to function7075 for strength, 6061 for weldability and cost, 316L for corrosion.
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  Plan the heat treat step4130 and 4340 distort if finish machining runs before stress relief.
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  Watch titanium tool engagementDwelling in the cut work-hardens the surface and dulls the next pass.

Certification scope is a filter, not a score. ISO 9001:2015 covers a general quality management system and applies to almost any buyer. IATF 16949:2016 is the automotive standard and matters if your part feeds an automotive or EV program. ISO 13485:2016 is for medical devices. ISO 27001:2022 covers information security, which is relevant when you are sending controlled drawings. This plant holds all four.

The paperwork that ships with the part matters more day to day. Raw material certificates with heat lot numbers let you trace a failure back to a melt. In-process inspection records show where the feature was measured and with what instrument. A final inspection report confirms the part met the drawing before it left the building. Ask for these on the first order, not after a problem.

Inspection depth is the practical differentiator. A shop that inspects the first article and then spot-checks is not the same as one that inspects 100% before shipment. For safety-critical parts, the second model is the only defensible one. This plant runs raw material checks, in-process monitoring, final inspection, and 100% inspection before shipment, with reports on request.

One number worth asking about is qualification rate. A shop tracking 99.99% is telling you it measures first-pass yield and acts on the misses. If a supplier cannot state a number, that is also an answer.

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  Match cert to marketISO 9001 for general work, IATF 16949 for automotive, ISO 13485 for medical.
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  Request mill certs with heat lotsTraceability is impossible without the lot number on the certificate.
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  Confirm 100% inspectionSpot-checking is not enough for a safety-critical feature.

Lead time in aerospace work is usually driven by material availability rather than spindle time. Standard aluminum and stainless stock is often on the shelf. Titanium and nickel alloys may need to be ordered, and that adds days before the first chip. Ask what is in stock and what has to be purchased, then ask again about the material you actually specified.

This plant quotes and returns a free DFM analysis within 12 hours, can start production within 24 hours, and ships parts in 3–5 days. Historical late-delivery probability is below 2%. Those numbers only hold when the drawing is complete and the material is standard, so treat them as a planning baseline and confirm against your specific part.

Order size is often a hidden constraint. Some shops have a minimum that rules out a single prototype. This plant has no minimum order quantity, so the same supplier can run one prototype and a 10,000+ part production run. That continuity matters because the process knowledge from the prototype carries into the production tooling.

Confidentiality is a real term, not a formality. Uploads are kept secure and confidential, and an NDA is available on request. If your drawing package includes controlled data or export-restricted geometry, settle the NDA before you upload, not after.

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  Separate material lead time from machine timeExotic alloys often add more days than the cutting itself.
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  Check MOQ earlyA minimum order can kill a prototype program before it starts.
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  Sign the NDA firstSettle confidentiality before drawings are uploaded, not after.