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paint color on engineering drawings 2

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Charles1111

Mechanical
Dec 4, 2019
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This could be an easy question, but I was wondering what the proper way to handle paint on drawings. Not the thickness or dimensions, but the actual paint color and how ordering a different paint color is handled. Currently, we don't put the paint on the drawing and order the part from our sister facility and specify the color in the order. This causes confusion at times and we receive an unpainted part.
We've discussed putting the actual color on the drawing, but if a different color is needed, we'd have to create a new part number and drawing. Also discussed putting the paint scheme on the assembly drawing, but that means the individual parts couldn't be ordered painted if we needed a spare, and could cross some of the same issues in ordering parts unfinished by accident.
 
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Do you refer to the dash number in other docs or just the root number? we have work instructions, or assembly drawings that refer back to the part drawing.
Apparently there was an AS9100 audit finding that we didn't have the paint color on the drawing or more likely, that we didn't have a part number assigned to the color... which I'm assuming a dash number is basically it's own part number.
 
To avoid color mismatches we specify the brand and color number, like "Sherwin-Williams #123456", and sometimes includes the preparation specs and primer specs too.
 
At my company we refer to an internal paint spec in the notes on the drawing ("Paint per Paint Spec 1234") that covers paint type, surface prep, etc. and do not put the color on the drawings to allow the same drawing number to cover multiple colors. As part of the PO we include a paint color form that indicates the color. As far as I know we haven't had problems since removing the color from the drawing and just specifying paint type on it. As far as specifying the color, we refer to the appropriate RAL number to avoid mismatching, although a very slight mismatch won't matter in our case.
 
For parts that come in different colored versions we will use a dash number to indicate color. The different manufacture and part #s for paint or pantone colors for injection molded parts will be included in a table on the drawing. We will usually release the drawing and part files as "12345-X" where X is the dash number that is determined by the color. This way we use the same generic drawing and part files for all the colors. We will also refer to the generic -X part in assembly drawings or work instructions. The only thing that refers to a specific -1 part would be the BOM for that color configuration and the associated PO.
 
Charles1111,

What do you want to accomplish?

If I am ordering widget power supply brackets, and the colour matters, then the engineering documentation must reflect it.

Your manufacturing process is to fabricate the part, then paint it. If there is only one colour you require, then you have one set of documentation, and you can get everything done by one vendor. If you require different colours (Look up the famous wisecrack by Henry Ford.[smile]), you need to separate the fabrication drawings and paint drawings. Your document tree looks something like this...

[ul]
[li]123-456 WIDGET POWER SUPPLY BRACKET WITH SILKSCREEN
[ul]
[li]123-458 WIDGET POWER SUPPLY BRACKET PAINT
[ul]
[li]123-459 WIDGET POWER SUPPLY BRACKET SUBSTRATE[/li]
[/ul]
[/li]
[/ul]
[/li]
[li]123-457 WIDGET POWER SUPPLY BRACKET ARTWORK[/li]
[/ul]

I added silkscreen artwork to make things more confusing. This document tree generates part numbers for the unpainted bracket, for the bracket with paint, and for the bracket with your sexy corporate logo on it. You have the option of generating a separate document tree for a bracket that is a different colour, and/or that perhaps has a Walmart logo.

If you want to call up colour, there is Fed STD-595B. You can look up RAL colour numbers. If you search a bit, you should find a better link than this[ ]one.

A general drafting standard is that you should not not tell the vendor how to paint your part. You should specify the colour, and how you are going to test it for ruggedness. You can always write out a separate paint specification document, and call it up when required.

--
JHG
 
We have faced the same basic expectation: "just put it on the drawing so that nobody misses it". Which sounds nice but editing drawings gets painfully costly when it's a non-engineering matter. Somethings these things get decided and managed outside of the Engineering department which amplifies the waste inherent in that solution.

So I would put a note on the drawing that states: "Refer to purchase order for paint requirements". Then I only touch the drawings once to put it behind me and I can drive various paint options on the ERP side of things.
 
It depends on the type of business one is involved in.

If it is build to order then referring to the order for the color makes sense; for example if the order can include custom colors, for which the business won't keep responsibility.

If it is build to inventory, then tying the color to a unique part number is necessary. For example I was able to order a replacement outside mirror assembly for a car that came pre-painted in a matching color. Similarly the work for the defense industry where replacement parts had to be stocked decades in advance of need and holding raw parts for JIT paint was not going to work.

 
For quick prototype shop prints/sketches I usually just call out most details in a note. For production parts I follow standard print practice. Paint being a material, it has a specific p/n and print detailing color, thickness, and other details of the paint layer itself, simply use that p/n in the assembly BOM. Surface prep is handled by calling out the appropriate corporate quality/cleanliness standard on the assembly print that also has the paint p/n callout. If its not on the purchase-level assembly print it shouldn't be on the part, paint included.
 
Charles1111,
You have a lot of folks offering advice, some good and some (maybe) not so good!
I will offer my own. I started in the Engineering Field 1n 1954 and during the following years I heard lots of people use the term "KISS". This meant "Keep It Simple Stupid". When I apply this advice in your case here I would keep it simple by having a single "Project Painting Specification". A Project Paint Spec would have all the information for "a specific" Project in one document. And when a change is required to a color or any other factor you only have to look in one place to make that change. Only a reference to the Paint Spec needs to be included on all applicable documents but it is a simple note pointing to one place.


Remember, Paint and Paint application will be different for different environments (example: Paint/Paint application in Saudi Arabia would be far different from Paint/Paint application in Alaska USA).


Sometimes its possible to do all the right things and still get bad results
 
geesamand said:
"Refer to purchase order for paint requirements".

What happens if the part requires masking?

Note how in the scheme I show above, I have the option of ordering and stocking 100 unpainted substrates. I can send 50 pieces out to the shop to be painted as per my drawing above. If one customer insists on hot pink, I can generate a new drawing, calling up the same substrate, and send five pieces out to the paint shop. These require different part numbers, and a different assembly tree. Several parts in the assembly may require the correct colour of paint. Note pennpiper's remarks, and once again, that famous crack by Henry Ford.

Interestingly, the original Model[ ]T Fords were painted green.

--
JHG
 
drawoh said:
What happens if the part requires masking?

You can still detail the drawing with masking details. (At my company, we paint only raw castings and fabrications, I didn't think about that).

My suggestion is to merely add a note referring the reader to the proper source for the exact paint. In my company's ERP system that's the item master which shows up on the Purchase Order. Then we can handle the various paint system options (no paint being one option) in the ERP data and spend less time revising drawings.

I prefer my proposal when the paint changes often and the mechanical design changes little. Then Engineering does not need to make new drawings for paint sake alone and all paint options can be driven by one drawing. If your workflow already requires job-specific drawings for every component, this is not an advantage.
 
In the architectural world we use RAL numbers. Its better than Sherwin Williams #1234 bc every fabricator wants to use a different paint manufacturer or chemistry.
 
Whenever I have a scenario like this I just add a chart to the drawing outlining part number and finish etc.

I work in the Subcontract CNC Turning industry but should be applicable in your line of work too 👍.

Link
 
There are many standards for color. The commercial world uses Pantone. You have to buy into that program to get the color chips, which are usually given to you with the nominal color and a light and dark chip for the range. When viewed in a standardized light booth you can then view if the color is correct. You refer to the color by the Pantone number. A simpler and cheaper version is in use by the government. That standard is AMS-STD-595A. A fan deck of these colors from SAE is about $210. More information can be found at SAE Colors
 
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