Steel Sheetmetal Finishing Options 1

[EngYuj]

I am looking for the most cost effective way to apply an opaque, black finish on some steel sheetmetal parts. I am considering powder coating, paint or black oxide. Which one of these are most cost effective?

 

[MikeHalloran]

You didn't mention corrosion resistance. Is that important?


Mike Halloran
Pembroke Pines, FL, USA

 

[plasgears]

Black oxide has the benefit of batch treatment and corrosion resist. Commonly used on fasteners.

 

[MadMango]

Quantity and physical size of parts will also play a role in cost. In addition to corrosion resistance, some processes have other concerns, such as coating thickness and "hanger marks" with powder coating. More info will yield you better responses.

"Art without engineering is dreaming; Engineering without art is calculating."

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[CoryPad]

Cost will be affected greatly by details you have omitted. Examples include quantities, part size, and final part performance requirements.

In general, I think you will find that the relative cost will be black oxide < paint < powder coating. In general, I think you will find that performance is the opposite.

 

[EngYuj]

Thank you for all of the responses. The quantities of these parts should not exceed 1000. Some of these parts might serve as cosmetic parts, so both corrosion resistance as well as durability will be required. I was primarily looking for a quick cost vs. quality/performance comparison, which was nicely provided by CoryPad. Although, if there is anything else I should know before making my decision, please let me know. Thanks!

 

[mcgyvr]

Easiest is to just get your part quoted by your sheet metal vendor, then ask what if the finish was "xxx" or "yyy"
Keep in mind most sheet metal vendors have inhouse painting/powdercoating.. Not many have a black ox line so it would then need to get shipped to another vendor then to you..(don't forget about shipping costs as many companies do)

 

[EngYuj]

Thanks for the suggestion mcgyvr. I will do that.

 

[dvd]

Instead of making a contractor quote processes that you may have no intention of using just ask their opinion up-front. If you want information from someone, be direct. Contractors want your business, but they will build the price of these little fishing expeditions into the price you pay. If you order more of this same widget in the future you will end up paying over and over again for the information that they would have given you for free if you just asked.

 

[MintJulep]

What are the parts used for? What is the environment, service, handling, exposure to sun, snow, chemicals, etc.?

Black oxide provides essentially no corrosion protection.

Paint (with proper surface preparation and primer) can be pretty good corrosion protection. Unless it gets scratched or chipped down to the base metal, then it's useless.

Powdercoat is the same, except that it is harder to scratch or chip.

Paint and powdercoat will both add thickness to the finished part, so if things are designed for a tight fit you'll need to take that into consideration.

You could also do a zinc coating with a black chromate. There are probably some other coatings that are black.

Is aluminum an option for the base metal? That would open the options to include a black colored anodize.

 

[KENAT]

As others say, with the information provided it's difficult to give much of an answer.

Black Oxide would be bottom of my list based on what little info you provide but I admit I haven't used it much.

My understanding is that to get any significant corrosion prevention from black oxide parts they need to be oiled. The black oxide layer helps 'trap' the oil, which is what really provides the protection. Black oxide parts tend to look quite dull if memory serves, probably not good for many cosmetic applications but only you'd know for yours.

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[mfgenggear]

black top coat paint with primer sealer.

black oxide helps but will easily corrode unless oiled.
no added dimension.

 

[unclesyd]

Here are some low temperature black coatings for iron and steel from Birchwood Casey that you may want to consider. This was our machine shop's standard coating on parts going into the mill whee they were subject very high humidity. We used them both as processed and top coated as mentioned above

I would give them a call to discuss your application.

http://www.birchwoodcasey.com/trutemp/index.html

 

[KENAT]

http://www.swdinc.com/black_oxide.htm

has a reasonable write up on Black Oxide.

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[AdamPeszel]

I have seen black oxide rust in wet applications.

If you are going to an outside vendor to have your parts made, ask them what process they recommend. While one method may be cheaper, your vendor may prefer another and the first method would cost more for a third party to do.

 

[MintJulep]

If you are going to an outside vendor to have your parts made, ask them what process they recommend

They will recommend the processes that they have the capability of doing that gives them the highest margin.

If the OP could quantify the performance requirements for the coating we could probably give a better recommendation.