Powder coating should occur on all aluminum parts (6061 and 5052) that have been manufactured in our shop.
There are 3 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.
Whenever a Aluminum part is done being manufactured and getting ready for powder coating the first step is to scrub it.
Scrubbing makes the part as smooth as possible and gets rid of any imperfections so the powder coat can stick as well as possible.
To scrub take a green scouring pad and start scrubbing hard back and forth on the part in ONE direction( Make sure to put a good amount of pressure because other whys it won't really get into the aluminum.
You can also take an orbital sander and put a circular pad on it and do the same process. (Its much quicker)
Whenever you are done scrubbing washing your part can help make sure its clean and let the acetone scrub go way quicker.
( If really backed up with parts not completely necessary to wash before Acetone)
For small parts just take a bunch of them and go into the marketing room sink and just give them a good rinse for about 30 sec each while scrubbing with a paper towel.
For large parts ask Ms. Rhea to let you through the Ag. room to use the hose out back. On the large parts make sure to wash and clean each side. Should take longer at like 4-5 min.
Make sure to dry your part thoroughly before Acetone scrubbing
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 shop towels to strip off the oxide. Fold the shop towels a couple times and thenput your hand with the towel onto the opeening of the acetone can and pour a little out. ( Just a quick tip to 90° and back)
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 and after scrubbing |
Watch the following video in full (15 min):
Safety Reminders
To diffuse any current in the system, touch the tip of the gun 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 Powder Coat Pro 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 twisting the voltage knob to a lower voltage ~10. This is used for hard-to-get-to places such as holes, and corners. You should do your low voltage spots first.
The high voltage setting can be turned on by twisting the voltage knob to a higher voltage ~40. 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.
When powder coat is applied too much, it often appears similar to the first 2 images below, a dimpled texture, or a dripping texture. This is caused when the coating of powder is too thick, and when it goes into the oven to cure, the powder melts and starts either dripping or creating a dimple texture due to uneven curing. The 3rd image is a example of a use case of low voltage, where the inside of the corner does not fully coat, so low voltage is needed.
(CWFishing is the source of the image, click on the image for a link to the source)
Once finished with your parts, or when you need to change colors, ensure you clean the booth and your gun.
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)
The Dwyer Mk.II is a device mounted on the side of the powder coating hood used to measure airflow from the powder booth vent.
Ensure that when the hood is on, the red gage fluid reads 0 inches of water column. If not, using the bottom left knob adjust until it reads 0. If it is unable to change, find a mentor for assistance.
Special still in progress