Some people may interpret the references to Standards on engineering drawings incorrectly.
What the Main Frameworks Are
These are the main frameworks that cover industrial work in the UK. There are DEF STAN specifications for defence contracts. AMS (Aerospace Material Specifications) are used for civil and military aerospace. BS EN standards are how British and international standards are structured. There are NADCAP standards, but NADCAP is actually an industry-managed accreditation scheme that goes to suppliers’ facilities to verify that they are producing in accordance with these standards.
What a Drawing Reference Actually Tells You
So a typical reference would be AMS 2404 / 0.025 mm min which is electroless nickel coating with a minimum thickness of 0.025mm. This reference also identifies the required test methods that the supplier would be expected to carry out to verify the coating thickness. (Some references are written with a class or grade suffix e.g. 5A to identify the expected hardness, or the level of porosity, and any post treatment requirements).
Checking Whether a Supplier Is Approved
The Qualified Manufacturers List (QML) for NADCAP-controlled processes is freely available for public search. Approval under DEF STAN processes is typically certified by the supplier and the associated approval certificate needs to confirm approval for the specific process and base material being offered. Approval for one process does not automatically extend to other processes even offered by the same supplier.
What to Ask for in Writing
Surface treatments carried out to recognised standards should be issued with a Conformance Certificate, detailing the standard(s) covered, the batch number or job number, process details, test results etc. This should be retained with relevant records of inspections.
How Tolerances Interact with Dimensions
05 mm from the bore diameter of that tube. Thus dimensions on a drawing for surface treatment should indicate whether these are pre-coat or post-coat dimensions and the coating applicator must be advised of this before starting the job.
If you want Surface Treatments, www.poeton.co.uk/surface-treatments/ is a good place to start.
Now you know what you are reading on a drawing reference for surface treatment work, specifying surface treatment work and procuring surface treatment work becomes a lot easier.