Aerospace Sourcing
Process houses

Aerospace Work for Finishing, Heat Treat, NDT and Cleaning Shops

Process houses are where aerospace parts most often fail an audit, so buyers and primes control them tightly. To win this work, a plating, anodize, heat treat, NDT or precision cleaning shop usually needs Nadcap accreditation or prime approval for each process, and certs that state the exact specification, revision, type and class performed.

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Why special processes get extra scrutiny

A special process is one where the result cannot be fully verified by inspecting the finished part. You cannot measure a heat treat's microstructure with calipers, or see a cleaning residue that will ignite in oxygen. Buyers therefore control the process itself: the equipment, the chemistry, the people and the records. That is why a machine shop's customer often tells it which anodizer or heat treater it may use.

For a process house this cuts both ways. Approvals take time and money, but once you hold them, every machine shop and fabricator serving those primes needs you. On the Space Coast, where launch and spacecraft work generate a steady flow of machined and welded hardware, approved processors are a bottleneck buyers regularly ask us to solve.

Nadcap: accreditation by process category

Nadcap is the industry managed accreditation program for special processes, administered by the Performance Review Institute and run by subscriber primes across aviation, space and defense. It accredits by process, not by company, so a shop holds a separate accreditation for each commodity it performs. Process categories include:

  • Chemical Processing (plating, anodize, conversion coating, passivation, chemical cleaning)
  • Heat Treating
  • Nondestructive Testing
  • Welding
  • Coatings
  • Materials Testing
  • Composites, Elastomer Seals and Additive Manufacturing

Not every customer requires Nadcap, and some primes approve processors through their own audits. But many make it a prerequisite for flight hardware. Our Nadcap accreditation page covers the audit process, cost and timeline.

Finishing: anodize, plating, conversion coating and passivation

Finishing callouts on aerospace drawings name a specification, a type and a class, and the cert has to match all three. Common examples:

  • MIL-PRF-8625 anodic coatings for aluminum (still often written as MIL-A-8625): Type I chromic acid, Type II sulfuric acid, and Type III hardcoat, with Class 1 undyed and Class 2 dyed. Type III is used for wear resistance and electrical insulation.
  • AMS 2700 passivation of corrosion resistant steels, which removes free iron and other contaminants from stainless surfaces, by nitric or citric methods depending on the material. ASTM A967 is a related industry standard.
  • Chemical conversion coating, cadmium and nickel plating, and other platings called out by AMS or military specifications.

The usual failure is not the chemistry. It is a cert that says "anodized per MIL-A-8625" without the type, class or revision, which leaves the machine shop unable to complete Form 2 of its first article report. Write certs that a quality engineer can check line by line against the drawing.

Heat treating and pyrometry

Aerospace heat treating runs to SAE specifications, such as the AMS 2759 family for steel parts, with separate detail specifications for low alloy, martensitic stainless, precipitation hardening and carburizing grades. Underneath all of them sits AMS 2750, the pyrometry specification that governs thermocouples, instruments, system accuracy tests and temperature uniformity surveys. Furnace class and instrumentation type set how often surveys and tests must be run.

Pyrometry is a frequent source of Nadcap heat treating findings. Since revision F, AMS 2750 requires that calibration, system accuracy test and temperature uniformity survey providers be accredited to ISO/IEC 17025, and that purchased thermocouples carry accredited calibrations. If you use outside pyrometry services, check their accreditation scope before your next audit.

Nondestructive testing

NDT shops in aerospace typically perform penetrant, magnetic particle, ultrasonic, radiographic and eddy current inspection to the methods and acceptance criteria in the customer's specifications. Personnel are qualified and certified under NAS 410, which requires training, experience and examination at each level, with a Level 3 responsible for the employer's NDT program. The employer, not an outside body, runs the certification program, so your written practice has to stand up to audit. The European counterpart is EN 4179.

NDT work on the Space Coast includes weld inspection on ground support equipment and pressure systems as well as inspection of machined and forged flight parts.

Precision cleaning and oxygen cleaning

This is the process most specific to the Space Coast. Launch vehicles and pads run on liquid oxygen, fuels and high pressure gases, and every component that touches those fluids has to be cleaned to a defined level, verified, and sealed against recontamination. Contamination in an oxygen system can ignite through particle impact or other mechanisms.

  • KSC-C-123 is Kennedy Space Center's specification for surface cleanliness of GSE fluid systems. It covers cleanliness levels, cleaning, verification test methods, handling and packaging.
  • ASTM G93 is the guide for selecting cleaning methods and apparatus for materials and equipment used in oxygen enriched environments. It covers chemical, solvent and aqueous processes but leaves the cleanliness level itself to the user's specification.
  • IEST-STD-CC1246, which grew out of MIL-STD-1246, defines product cleanliness levels for particles and nonvolatile residue and is widely used in contracts.

Buyers will ask what levels you can certify to, how you verify them (particle counts, nonvolatile residue analysis), what size parts and tubing lengths your cleanroom and tanks handle, and how you bag and cap cleaned parts. Commercial launch companies may also hold their own cleaning specifications.

Typical process requests from Space Coast programs

Most special process work on the Space Coast arrives attached to a machined or welded part that is already on a schedule. Requests we expect to see most often include:

  • Type II and Type III anodize on aluminum brackets, housings and fixtures for ground equipment and spacecraft structures.
  • Passivation of stainless fittings, tubing and manifolds before precision cleaning for oxygen or propellant service.
  • Solution treat and age of 17-4PH and other precipitation hardening steels, and stress relief of welded GSE frames.
  • Penetrant and radiographic inspection of welds on pressure system assemblies and lifting equipment.
  • Precision cleaning, verification and bagging of valves, regulators, flex hoses and tubing runs for launch pad systems.

Turnaround matters as much as approvals here. A processor that can quote a firm lead time and hold it is worth a lot to a buyer working toward a launch window.

What to put on a process house capability sheet

  • Each process, with the specifications, types and classes you perform.
  • Nadcap accreditations by commodity, with expiry, and any prime approvals.
  • Tank sizes, furnace work zones and classes, cleanroom class and largest part envelope.
  • NDT methods and the number of qualified Level 2 and Level 3 personnel.
  • Typical turnaround and whether you offer expedite.
  • A sample cert showing how you list spec, revision, type and class.

Join as a process supplier, free

Sign up at /suppliers/ to receive RFQs as a supplier. Buyers send us jobs that need finishing, heat treat, NDT and precision cleaning, and we route the special process step to a processor whose approvals match the flow-down, then check the cert before the parts move on. You sign a flow-down NDA before seeing customer data. We review every signup and contact you when work fits; we do not promise a set number of RFQs. See also machine shops, test labs, and the supplier hub.

Questions

Does my plating or heat treat shop need Nadcap?

It depends on your customers. Nadcap accredits special processes by category, including Chemical Processing, Heat Treating, NDT, Welding and Coatings, and many aerospace primes require it for processors working on flight hardware. Other customers approve processors through their own audits, and some ground equipment work requires neither. If you want to serve the machine shops and fabricators that supply primes, Nadcap in your main process usually widens the pool considerably.

What is AMS 2750 and why does it matter?

AMS 2750 is the SAE pyrometry specification used for aerospace thermal processing. It covers thermocouples, instruments, system accuracy tests and temperature uniformity surveys, and sets test frequencies by furnace class and instrumentation type. It is a common source of Nadcap heat treating findings. Since revision F, it also requires pyrometry calibration and survey providers to be accredited to ISO/IEC 17025.

What goes on an aerospace process cert?

At a minimum: the customer, purchase order and part number, quantity, the specification and its revision, the type, class or method performed, any test results the spec requires, the date and lot or batch, and an authorized signature. If the drawing calls for MIL-PRF-8625 Type II Class 1, the cert must say exactly that. Vague certs force the customer to stop and ask, and can hold up their first article inspection.

What standards apply to oxygen cleaning on the Space Coast?

At Kennedy Space Center, KSC-C-123 sets cleanliness levels, cleaning, verification, handling and packaging for GSE fluid system surfaces. ASTM G93 is the guide for choosing cleaning methods for equipment in oxygen enriched service. IEST-STD-CC1246 defines particle and nonvolatile residue cleanliness levels often written into contracts. Commercial launch providers may impose their own specifications, which take priority where they apply.

Who certifies NDT technicians for aerospace?

The employer does. Under NAS 410, each employer writes and runs a certification program that combines classroom training, on the job experience and examinations, with a Level 3 responsible for the program. The Aerospace Industries Association maintains the standard but does not run training or exams. EN 4179 is the European equivalent. Customers and Nadcap auditors review your written practice and personnel records.

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