Designing for Powder Coating
 

We have a new sponsor that is willing to do powder coating for us, so we're considering having our robot parts powder coated this season. For teams that have been doing this for years, what pointers can you give for designing a robot that is ready to be powder coated?

• Do you make dimensional allowances to account for the powder thickness?
• What kind of cleaning or surface prep is required before sending your parts out for coating? Do you mask off certain things?
• What kind of "clean up" is required after you get your powder coated parts back? Are bolt clearance holes OK or do they need to be reamed, tighter tolerance things like bearing pockets, etc?
• Any other words of wisdom?

Thanks.

Re: Designing for Powder Coating
 

Last year, 2220 had our chassis powdercoated by one of our sponsors. We certainly haven't been doing powdercoating for a long time (I'm hoping to see 254 get in on this thread), but there were a couple of things we learned:

For hole tolerances, if we dimensioned it as a clearance hole, it was completely fine (we just used the clearance hole setting in Creo for that hole size, you can look up whatever size that gives you to find drill bits for that size, otherwise if you're having a CNC sponsor do that for you they should be able to easily recognize it).

We didn't do any major surface prep because our sponsor handles ridiculous volumes of powdercoated parts, so they basically have the entire process from intake through application to baking automated.

For dimensional tolerances, powdercoats can vary in thickness, so talk to your sponsor-- depending on the application method, they can be 1 mil to 10 mil in thickness* (though in our experience it tended towards the lower end of that). Definitely talk to your sponsor about their recommendations.

*might be wrong on this, main point is that it varies

Re: Designing for Powder Coating
 

Re: Designing for Powder Coating
 

If you add or modify parts after the powder coating is done, they won't be powder coated.

We PC with black, so using black spray paint for added parts doesn't look to bad

Re: Designing for Powder Coating
 

Unless, like Team 11, you powder coat and bake the parts yourself.
Then you only see that if the part was thrown together or made on the road.

You do need to consider the hole sizes if you allow the powder to get into the holes.

Team 11 uses sand paper, grinds, sand blasts and masks parts as preparation.

Re: Designing for Powder Coating
 

We got it for the first time last year. We didn't do any preparation, it was a kind of a last minute thing. Unless your robot needs super tight tolerances, it wont make a difference. We had had to drill out a few holes for rivets because they were tight. But other than that, I don't think we did much else. We didn't weld, so we powdercoated literally everything with no tape or whatever to keep areas clear.

Re: Designing for Powder Coating
 

For teams that use a WCD chassis, do you make any specific allowances for the pockets in the siderail that the bearing blocks ride in?

Re: Designing for Powder Coating
 

We do. I absolutely hate having to file/sand off powder coat. So, we put in an allowance for it. More importantly, we make our axles a little longer too. I can never remember how much the allowance was, and every year, we have to look back at the previous year's robot or CAD model.

This is something we need to add to our internal Standard Operating Procedure.

Re: Designing for Powder Coating
 

Another thing to note if you are doing a light color (say fluorescent yellow) things like sharpie and the material call out printed on your parts will show through your powder.

Like 254 we anodize all tight tolerance parts.

For clean up we have found that rivet holes especially 1/8" have to be reamed. Masking parts typically makes for a cleaner look than sanding/filing off powder.

Re: Designing for Powder Coating
 

I believe we add .015 to the cutouts on our frame.

Re: Designing for Powder Coating
 

Our sponsor sandblasted it for us, so yeah just find a sponsor that would be willing to do that, or sandblast it yourself.

When we powder coated our arm, we had to cut off part of the underneath of the catapult arm, so as long as you get it clean cut and nice looking you won't need to powder coat it because we still got the Imagery award and Engineering Inspiration and Regional winner all in one Regional.

Re: Designing for Powder Coating
 

Has anybody weighed their chassis before and after powdercoating - how much weight should I expect it will add?

Re: Designing for Powder Coating
 

When I was dealing with powder coating, 1885, I would just drill the hole over again, the little powder coating that was in the hole would come right off.
You can also ask the person not to put any powder in the holes....that's probably the easiest thing.
But if you take a bolt and thread it through then it would probably come off itself.

Re: Designing for Powder Coating
 

Out of curiosity who is the sponsor? I am local and am wondering about getting some personal parts powder coated.

Keep in mind when powder coating you must use high heat masking tape. For masking holes I have found silicone tapered plugs work best.