Powder coating should occur on all aluminum parts (6061 and 5052) that have been manufactured in our shop.
There are 2 things that we can do in the shop to clean an aluminum part:
When and why you should use these cleaning processes is detailed below.
The sooner a part gets powder coated after manufacturing, the better due to aluminum oxidation.
Aluminum has a very high affinity to oxygen. When a new aluminum surface is exposed in the presence of air, it quickly develops a thin, hard film of aluminum oxide. This aluminum oxidation is both good and bad - good in that it provides a layer of protection against corrosion, but bad in that that layer can also provide resistance to powder bonding.
For powder coating, if an aluminum oxidation layer has built up on the part, we need to strip off this layer from the part before coating.
To do so, we can scrub the part down with acetone using steel wool or a finishing pad to strip off the oxide. A few reminders when cleaning a part with acetone:
You should scrub your part with acetone when the part has been sitting around for a while |
Outgassing is the process of removing embedded or trapped gasses on the faces of your aluminum part. It sounds more complicated than it actually is - in reality, all we are doing is baking the part.
The reason outgassing is important is because most of our parts are coated with coolant due to machining the part on the router or the mill. This coolant or oil can get embedded into the part and add irregularities into your powder coat layer.
To outgas, we can place the part in the oven at 400 degrees and bake for 20 minutes before powder coating to release any gasses trapped in by the coolant that coated the part during manufacturing.
You should outgass your part when the part had been coated in coolant during manufacturing |
Watch the following video in full (15 min):
Safety Reminders
To diffuse any current in the system, touch the emitter rod to the grounding cable before and after working on a part. |
Getting a uniform layer of powder onto a part can be a little difficult. We have the Eastwood dual voltage gun, and therefore we have the ability to fine tune some settings to get a more perfect part.
The low voltage setting can be turned on by setting the switch to setting #1. This is used for hard-to-get-to places such as holes, and 90 degree corners. The diffuser is required when using the low voltage setting. You should do your low voltage spots first.
The high voltage setting can be turned on by setting the switch to setting #2. This should be your default setting when using the powder coat gun. You can take the diffuser off while using the high voltage setting if you prefer - this will get you a narrower cone of powder spray.
1. Some box tubing was just manufactured on the CNC mill and is covered with coolant. How should you clean your part before powder coating? (Choose all that apply)
2. A student just manually cut some axle stock on the band saw (no coolant was used). How should you clean your part before powder coating? (Choose all that apply)
3. The robot has been sitting in the shop all season, and we are about to attend an offseason event and want to make the robot look good. You disassemble the shooter, and want to powder coat the shooter side plates. How should you clean your part before powder coating? (Choose all that apply)
4. When cleaning up the powder coat oven, what should you NOT do? (Choose all that apply)
5. How long should you put your part in the oven for? (Choose all that apply)
6. What should you never do when powder coating? (Choose all that apply)
7. How much powder should you put in the powder container of the gun? (Choose all that apply)