Paint Specification on Drawigs

[drawoh]

I want to call up paint on some engineering drawings. I have an RAL colour number. I want to call up a textured finish. I don't have any chemical or fire issues. I do want a fairly sturdy finish. I do not want to specify the paint material or process, as to do otherwise is poor drafting process.

Is there a way to specify how tough a paint finish is?

I am going to call my paint shop and ask about specifying textured finishes, but I would appreciate any remarks about this, too.

Thank you.

--
JHG

 

[CoryPad]

Tough, as in resistance to:

ultraviolet radiation
organic solvents
acids
bases
fuels
mechanical abrasion

Sure, you can write drawing notes covering these and other requirements, although usually another engineering document like a Materials Specification (or Product Specification or Performance Specification, etc.) is created with all of the requirements. This other document would be referenced on the drawing. There are many consensus standards from ISO, ASTM, etc. that cover this area.

 

[drawoh]

Corypad,

UV, abrasion, and getting the crap beat out of it. It is an electro optics device costing something over $100K. They will beat the crap out of it gently.

--
JHG

 

[TVP]

My suggestion, you need to create a separate specification that exactly defines what type of coating will be used and what the performance requirements, including testing, will be. A typical durable finish for steel components comprises a zinc phosphate layer followed by non-Cr seal, then 20-30 micrometers of epoxy (either electrocoat or spray), followed by 50-100 micrometers of polyurethane (typically spray). The PU has UV resistance, toughness, while epoxy provides resistance to corrosion, chemicals, etc.

 

[TomDOT]

Scrape adhesion: ASTM D 2197 (it's a how-to, you need to figure out a cutoff value)

Abrasion: ASTM D 4060 (Taber Abraser, again, it is a how-to, figure out a cutoff value)

UV Resistance: Accelerated UV testing, the one for paint is D 4587, generalist is G154 for the most common methods (fluorescent tubes instead of xenon or carbon arc)

Et cetera.

 

[WKTaylor]

Drawoh...

NOT being specific RE your finish requirements seems unwise: finishes are as much a part of an engineering definition as are the configuration, metals/heat-treatments, machining processes, etc.

Years ago a world-wise engineer counciled me as follows.

"You deserve to get what you ask for: but if You don’t ask for very much, don’t-expect to get very much.” -- Ron Nelson, Boeing Engineer

Regards, Wil Taylor

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