MIL-PRF-8625 Anodizing Services for Aerospace and Defense Parts
Need MIL-PRF-8625 anodizing services, including Type III hard anodize? Aerospace Sourcing places your parts with a processor whose Nadcap scope or prime approval covers the exact type and spec, flows down masking, seal and thickness, and checks the lot cert before shipping. Send the drawing, the finish callout, quantity, alloy and temper.
Updated
How to choose MIL-PRF-8625 anodizing services
Pick the anodizer by what it is approved to do, not by what it says it can do. The right processor holds a quality system, a Nadcap chemical processing accreditation or a direct prime approval that names anodizing, and a scope that covers the type you are calling out, whether that is Type II sulfuric, Type III hard coat or a non-chromate Type IC or IIB.
A search for aerospace anodizing near me returns every shop with a tank line. Distance matters less than the approval, the line's capacity for your part size, and whether the shop can mask your geometry. A wrong processor costs a stripped lot, lost base metal and a schedule slip.
We serve buyers anywhere in the United States. We do not run tanks. We match each job to a processor whose approvals fit the drawing and your customer's flow-downs, and we manage it through delivery. The broader picture of heat treat, plating, peening and NDT is on our aerospace special processes page. This page covers anodize only, from the buyer's side of the desk.
Nadcap chemical processing: what AC7108 actually covers
Nadcap accreditation for anodizing is granted under the chemical processing criteria, AC7108, with anodizing audited to the AC7108/8 slash sheet. A certificate that says chemical processing is not enough on its own. Read the scope page.
Nadcap is administered by the Performance Review Institute. The chemical processing family is split into slash sheets, and a processor is audited only to the ones it selects. The sheets a buyer of anodize should recognize:
| Checklist | What it audits | Why an anodize buyer cares |
|---|---|---|
| AC7108 | Base criteria for chemical processing | Required for every chemical processing scope |
| AC7108/8 | Anodizing (not for metal bond) | The core approval for MIL-PRF-8625 work |
| AC7108/4 | Solution analysis and testing | Bath chemistry control behind every tank |
| AC7108/3 | Surface preparation prior to metal bond | Bonding prep is a separate approval from general anodize |
| AC7108/13 | Brush anodizing and plating | Touch-up and local repair are audited separately |
| AC7108/14 | Stripping of coatings | Covers the strip step used in rework |
Published scope certificates list AC7108/8 as anodizing not for metal bond, with AC7108/4 beside it, and the process lines underneath. A shop accredited for sulfuric anodize may not hold hard anodize. The certificates also state that current scope and expiration live on the Qualified Manufacturers List at eAuditNet. Check the live listing on the date your parts are processed, not a PDF the shop emailed last year.
Have a part like this?Send it in under a minute. A person replies within 1 business day.Customer approved processor lists
Many primes approve special process sources themselves, and their approval can be narrower than Nadcap. If your contract flows one of these lists down, the processor has to be on it for the specific specification.
Boeing's D1-4426, Approved Process Sources, is the most widely cited example. Boeing's Q020 purchase order clause requires sellers and their subcontracted process sources to use processors approved in D1-4426 where it applies, to flow that requirement down, and to keep a certificate for each D1-4426 process that names the processor and the processing dates. Other primes publish their own special process requirements in supplier quality documents, and the details differ, so read the clause your contract actually invokes rather than assuming it works like Boeing's.
What we check before a lot goes in the tank:
- The processor is approved for the prime's process specification, not just MIL-PRF-8625, when the prime's spec is the one on the drawing
- The approval is current and covers the type and class on your drawing
- Any prime specific requirement, such as a certificate format or record retention period, is on our purchase order to the processor
- If the part passes through a machine shop first, the machine shop knows it may not pick its own anodizer
Type II, Type III and what the callout must say
State the spec, type, class, seal and, for Type III, thickness. If the drawing is silent on type, revision F allows the processor to furnish any of Types I, IB, IC, II or IIB, and an unstated class lets them pick dyed or undyed. A short callout is how a buyer ends up with the wrong part.
| Field | Typical entry | Problem if missing |
|---|---|---|
| Spec and revision | MIL-PRF-8625F with amendment, or the AMS or prime spec your customer flows down | Processor works to an old or different document |
| Type | II, III, IC or IIB | Processor chooses for you |
| Class | 1 undyed or 2 dyed, with color | Color mismatch or unwanted dye |
| Seal | Sealed, unsealed, or a named seal chemistry | Type III left unsealed when you needed corrosion resistance, or sealed when you needed wear |
| Thickness | For Type III, a value and tolerance | Defaults to the spec nominal |
| Masking | A view or note naming surfaces | Threads and bores grow out of tolerance |
Two contract points sit inside the finish choice. Type I chromic anodize and dichromate seals involve hexavalent chromium, and on DoD deliverables DFARS 252.223-7008 limits hexavalent chromium in delivered items unless the contracting officer approves an exception, which is why Types IC and IIB exist as non-chromate alternatives. And for Class 2 work, revision F made color a lot acceptance criterion, so the color requirement has to be stated in a way the processor can check. The engineering trade is on our Type II vs Type III anodize page, and the full spec detail is in the anodizing reference.
Masking callouts that processors can follow
Masking is where most anodize rework starts. A processor can only mask what the drawing shows, so put masked surfaces on a view, not in an email thread.
- Name each masked feature: threads, bearing bores, mating faces, electrical bonding and grounding points
- Say how the masked edge should be finished, for example whether chem film touch-up per MIL-DTL-5541 is acceptable on bare areas
- Show where rack or contact marks are allowed, since every anodized part has a contact point that stays bare
- For blind tapped holes, say whether they are plugged, masked or left to coat, because small and tapped holes can range from no film to full thickness
- On complex parts, ask for a masking plan or a marked up print back from the processor before the first lot
Hard coat grows each surface by roughly half its thickness, and thread pitch diameter by about four times that growth, so threads are usually masked or cut oversize. Engineering decides; we make sure the decision reaches the processor.
Verifying thickness, coating weight and seal
Ask for the verification the spec requires, reported against your lot. Types I through IIB are accepted by coating weight, and Type III is accepted by thickness, with coating weight allowed as a substitute at the procuring activity's option.
- Coating weight is measured on undyed, unsealed parts or panels by stripping the oxide and weighing the difference. It is a destructive test, which is why it is often run on panels processed with the lot.
- Type III thickness is the average of at least eight eddy current readings, with a metallographic cross section as the referee method in a dispute. Revision F names ASTM B244 and ASTM E376 for eddy current measurement, and the test report should say which was used.
- Seal performance on sealed coatings is tested by 336 hours of neutral salt spray to ASTM B117. Salt spray takes two weeks, so ask the processor how its current results cover your type and seal rather than expecting a fresh test on every lot.
One revision F change matters to buyers. It removed wording that some read as requiring the anodizer to verify part dimensions after coating, leaving a thickness measurement as the anodizer's job. If coated dimensions matter, order dimensional inspection after anodize as a separate step.
Lot testing and process control behind the cert
A good anodize cert is the end of a chain of controls you rarely see. Knowing what sits behind it tells you what to ask on a source audit.
Under revision F, the anodizer runs process control tests at least monthly, with no more than 35 days between tests, analyzes each tank at least every two weeks, and keeps bath records for at least a year after the order. Nadcap's AC7108/4 checklist audits that solution analysis and testing system. On the lot level, the cert should tie a specific job to those controls.
A complete lot cert from the processor shows:
- Processor name and address, and the Nadcap or prime approval that applies
- Spec, revision, type, class, color and seal
- Part number, revision, quantity and the processor's job or lot number
- Processing date, which matters for approvals that must be current at the time of processing
- Thickness or coating weight results and the method used
- A signed statement of conformance
The cert must also match the special process entries on your AS9102 first article.
Rework limits: stripping and re-anodizing
Treat stripping and re-anodizing as a controlled rework that needs your approval, not a routine fix. Anodic coatings grow from the aluminum itself, roughly half into the original surface and half outward, so every strip removes base metal that the next coat will not give back.
- Stripping is its own audited process. Nadcap has a separate checklist, AC7108/14, for stripping of coatings, and processor scope certificates list stripping as an internal rework process. A processor approved to anodize is not automatically approved to strip.
- The anodizing reference notes that Type III should not be applied to surfaces that will later need dimensional restoration by rework. On a close tolerance hard coat feature, one strip can consume the tolerance.
- Some prime and process specifications limit how many times a part may be stripped and recoated. Where your drawing or prime spec sets a limit, it governs. Where it does not, decide your own rule before the first nonconformance, not during it.
Our purchase orders to processors state that no lot may be stripped and reprocessed without written approval, and any rework shows up on the cert. If you have your own limit, we flow it down word for word.
Sequencing anodize with machining and heat treat
Anodize normally comes after final machining and after heat treatment. Heat would damage the coating, and any cut after anodize leaves bare aluminum that needs touch-up.
- Rough machining, then any stress relief the routing calls for.
- Solution heat treat and age to the final temper, for example under AMS 2770 for wrought aluminum, before the part sees the anodize line.
- Finish machining, including any pre-coat dimensions engineering set for Type III growth.
- Penetrant inspection where required, since a coating can bridge and hide a surface crack.
- Anodize, dye if Class 2, then seal or leave unsealed as specified.
- Lapping or honing of Type III to final size where the drawing allows it.
- Primer or paint, with the seal choice agreed with the paint system.
- Final inspection and marking by a method that does not damage the finish.
Put the alloy and temper on the request, because alloy changes hard coat results and castings bring color and porosity limits. When a part needs machining and anodize on one order, our aerospace CNC machining page explains how the outside process is carried inside one job.
What drives anodize lead time and cost
Anodize cost and lead time are set by setup and handling more than by tank time. We do not publish prices.
- Masking labor is often the largest variable on aerospace work
- Racking for large, heavy or odd shaped parts, and whether the line's tanks fit the part
- Lot size, since many processors set lot charges that make one piece expensive
- Type III is a separate process line, and fewer processors hold hard coat in their approved scope
- Approval scope, since fewer processors hold a given prime approval
- Testing such as coating weight panels
Our special process cost page goes deeper on pricing drivers across finishing work.
What to send with your anodizing request
Send enough for a processor to say yes or no on the first read. The list below is what decides which processors can take the job.
- Drawing at the current revision, with the finish note and any masking views
- Alloy, temper and product form, for example 7075-T7351 plate or A356 casting
- Spec, type, class, color, seal and Type III thickness
- Nadcap or prime approval requirement, with the clause or list name
- Quantity, lot size and whether parts arrive machined, heat treated and inspected
- Cert requirements and any first article needs
- Your rework rule and the drawing's export control status
- Need date
If the drawing is ITAR or CUI controlled, do not attach it to the web form. Our confidentiality page and controlled programs page explain how controlled data moves by a secure method to authorized U.S. persons.
How Aerospace Sourcing handles anodize work
We are a sourcing service, not an anodizer, and we hold no Nadcap accreditation ourselves. We route parts to processors that hold what the job requires.
- One quote, one lead time, one point of contact and one purchase order across every shop in the routing
- Mutual NDA before files are shared
- Specs, masking, seal, thickness, approval and rework rules flowed down to the processor
- The lot cert checked against the drawing and our order before parts ship
- A certificate of conformance with every order, plus the process certs you require
A person replies within one business day, and rush requests are prioritized.
Request anodizing
Send the drawing and finish callout through the special process request form. It is preset for special processes, so it asks for the spec, type, approval requirement and alloy up front, which are the details that decide which anodizers can quote your parts.
Send the job. A person replies within 1 business day.
Part, quantity and date are enough to start. Drawings and the mutual NDA follow by reply, and controlled programs never send technical data through this site.
We have it.
Reference . A person replies within 1 business day. Watch for our email from [email protected].
Questions
Does an anodizer need Nadcap to do MIL-PRF-8625 work?
Not always. MIL-PRF-8625 itself does not require Nadcap. The requirement comes from your drawing notes, your prime contractor's purchase order clauses or an approved process source list. Many flight hardware programs require Nadcap chemical processing accreditation covering anodizing under AC7108/8, a prime approval, or both. Commercial and some ground support work may only need an AS9100 or ISO 9001 shop. Read the clauses in your contract, then check the processor against them on the date of processing.
How do I check whether an anodizer's Nadcap accreditation is current?
Look the processor up on the Qualified Manufacturers List on eAuditNet, which Nadcap certificates name as the place where current scope and expiration are listed. A PDF certificate shows scope at the time of the audit, and the expiration moves with each audit cycle. Confirm the listing covers AC7108/8 and the specific process line you need, such as hard anodizing, and that it will still be current when your parts are processed.
Can anodized aerospace parts be stripped and re-anodized?
Often yes, but only as controlled rework with the buyer's approval. Because the coating grows from the aluminum, stripping removes base metal, and a close tolerance Type III surface may not survive even one cycle. Stripping is audited separately by Nadcap under AC7108/14. Some prime specifications limit how many times a part can be stripped. Put your rule on the purchase order before the first lot.
Should anodize be done before or after heat treat?
After. Aluminum parts are normally heat treated to final temper first, then finish machined, inspected and anodized. Heat applied after anodizing can damage the coating, and machining after anodizing exposes bare metal that then needs touch-up. If your routing includes stress relief between rough and finish machining, that also comes before anodize. When the drawing sets a different order, the drawing governs.
What should an anodize certificate include?
The processor's name and approval, spec and revision, type, class, color and seal, part number, revision, quantity and lot or job number, the date of processing, thickness or coating weight results with the measurement method, and a signed statement of conformance. For Boeing work under D1-4426, the cert must name the processor and processing dates for each approved process. Ask for one cert per process per lot.
Can you handle machining and anodizing on one order?
Yes. We can source the machining, heat treat, inspection and anodize as one job with one purchase order and one point of contact. We set the sequence from your drawing, flow the finish callout and approval requirements to the anodizer, and check each process cert before the parts ship with a certificate of conformance. Send the full drawing package through the quote form so the whole routing can be planned at once.
Related
Sources
- Performance Review Institute: Nadcap program overview
- Omnex: Nadcap AC7108 chemical processing course outline listing AC7108 slash sheets
- Nadcap chemical processing scope of accreditation example (CESA), listing AC7108/8, AC7108/4 and eAuditNet QML
- Boeing: Q020 D1-4426 Approved Process Source clause
- DLA ASSIST via ibiblio: MIL-A-8625F anodic coatings for aluminum and aluminum alloys
- DLA ASSIST via ibiblio: MIL-A-8625F Amendment 1
- Finishing and Coating: rollout of MIL-PRF-8625 revision F and implications for anodizers
- Acquisition.gov: DFARS 252.223-7008 prohibition of hexavalent chromium
- SAE: AMS 2469 hard anodic coating treatment of aluminum alloys
- Aluminum Anodizers Council: anodizing reference guide
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