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There was recently a thread on rims where a few members, including myself brought up powder coating.
I am a huge fan of powder coating. The finish is tough as nails, and looks good too. And for folks like myself that think less is more when it comes to chrome, It is a good option.
Powder coating has become so popular in recent years that there are shops popping up everywhere. This can be really good for the consumer, but there is a down side too.
While there are a lot of shops that powder coat these days, there are relatively few that do it correctly. So I thought I would share my experience in this subject.
I was a maintenance manager at a trucking company that had 300 + vehicles on the road. We instituted a wheel refurbishing program where we would take our truck wheels, media blast them. Inspect them for cracks, bends, and wear in the lug areas.
If they failed in any of the above, they were destroyed and replaced. If they passed we would have them powder coated.
In our search for a shop that would do the coating we actually found a shop that did a turn key process where they took our wheels and did the entire job for us. Even better yet, they would bring the refurbished rims back with the tires of our choice mounted, and pick up the next batch to be done. They also brought back the rejects for us to dispose of so that we could verify that they were indeed bad rims.
This worked out great until one of our trucks that was running a route on a hot summer day in the hill country west of Austin sheared the wheel studs and lost a set a duals. Our first thought was that our shop people failed to torque the lugs, but on inspection, we saw somenting unusual.
The coating between the rims looked as if it had melted and was slung out by centrifugal force, and that is indeed what had happened.
We didn't know if this was just a case of bad product or what, so we called the shop and their supplier of coatings. The supplier sent a rep out to evaluate our issue, and before he arrived, we had another truck do the same thing!
When the rep arrived, he looked at the damaged wheels and tested the coating thickness and hardness. He verified what we suspected, that the coating had not been fully cured and the heat from excessive braking did indeed melt the coating between the duals creating a loose wheel situation. Once that happened, it was only a matter of time before the shifting wheels sheared off the studs.
At that point, the Dupont rep, my tire salesman, and myself visited the refurb shop.
The shop was set up where the wheels were prepped, they were preheated and hung on an overhead track where they were sprayed and sent into the oven for curing.
The track was constantly moving so this was a sort of assembly line process. The oven was a long narrow enclosure about 20 ft long with heating elements spaced evenly throughout it.
The Dupont rep and shop foreman verified that the temperature was correct and that the speed of the conveyor was such that the wheels did get the correct amount of oven time.
We then tested the finished wheels and 3 out of 4 failed! At that point, the process was shut down until the cause could be found. The Dupont rep took samples of the unused coating back for testing and the shop foreman proceeded with equipment checks where they found that three of the heating elements inside the oven were not functioning. That basically reduced the amount of curing time enough that the heavier wheels did not completely cure.
Once that was corrected. the process was started back up.
From that point on, we started testing wheels when we took delivery. We still had an occasional failure that got sent back, but the majority passed and went into use without any more drama.
In this case, the shop just experienced an equipment failure, but after that incident, when I decided to have items powder coated for my personal use, I started looking at different shops and asking questions. What I found is that many of these shops have no clue as to what they are doing. They just spray and bake. Most of them have the oven temperatures right, but will heat small and large parts at the same time and not allow the larger parts enough oven time to totally cure.
Now if you are having lawn chairs or even bike parts like luggage racks done, this is probably not an issue other than that partially cured coating is not going to be as hard as it should be.
Even parts like front wheels may never see an issue. Rear wheels may be a different story.
The bottom line is talk to a shop before hand and ask questions about their process. I also tell them before they start that I will be testing the finished product.
When it comes to masking. Always specify that any machined surface that mates to other parts needs to be masked off. This will not only ensure proper fit at reassembly, but would also prevent the failures we saw on our truck wheels in the event that the coating fails.
As far as testing goes, it is a very simple process. Go to Home Depot or Lowes and pick up a can of MEK solvent. Wet a Qtip and rub the coating rapidly 10 or 12 times. If the coating is properly cured, this will have no effect on the finish. If not, the coating will smear and it needs to be redone.
I am a huge fan of powder coating. The finish is tough as nails, and looks good too. And for folks like myself that think less is more when it comes to chrome, It is a good option.
Powder coating has become so popular in recent years that there are shops popping up everywhere. This can be really good for the consumer, but there is a down side too.
While there are a lot of shops that powder coat these days, there are relatively few that do it correctly. So I thought I would share my experience in this subject.
I was a maintenance manager at a trucking company that had 300 + vehicles on the road. We instituted a wheel refurbishing program where we would take our truck wheels, media blast them. Inspect them for cracks, bends, and wear in the lug areas.
If they failed in any of the above, they were destroyed and replaced. If they passed we would have them powder coated.
In our search for a shop that would do the coating we actually found a shop that did a turn key process where they took our wheels and did the entire job for us. Even better yet, they would bring the refurbished rims back with the tires of our choice mounted, and pick up the next batch to be done. They also brought back the rejects for us to dispose of so that we could verify that they were indeed bad rims.
This worked out great until one of our trucks that was running a route on a hot summer day in the hill country west of Austin sheared the wheel studs and lost a set a duals. Our first thought was that our shop people failed to torque the lugs, but on inspection, we saw somenting unusual.
The coating between the rims looked as if it had melted and was slung out by centrifugal force, and that is indeed what had happened.
We didn't know if this was just a case of bad product or what, so we called the shop and their supplier of coatings. The supplier sent a rep out to evaluate our issue, and before he arrived, we had another truck do the same thing!
When the rep arrived, he looked at the damaged wheels and tested the coating thickness and hardness. He verified what we suspected, that the coating had not been fully cured and the heat from excessive braking did indeed melt the coating between the duals creating a loose wheel situation. Once that happened, it was only a matter of time before the shifting wheels sheared off the studs.
At that point, the Dupont rep, my tire salesman, and myself visited the refurb shop.
The shop was set up where the wheels were prepped, they were preheated and hung on an overhead track where they were sprayed and sent into the oven for curing.
The track was constantly moving so this was a sort of assembly line process. The oven was a long narrow enclosure about 20 ft long with heating elements spaced evenly throughout it.
The Dupont rep and shop foreman verified that the temperature was correct and that the speed of the conveyor was such that the wheels did get the correct amount of oven time.
We then tested the finished wheels and 3 out of 4 failed! At that point, the process was shut down until the cause could be found. The Dupont rep took samples of the unused coating back for testing and the shop foreman proceeded with equipment checks where they found that three of the heating elements inside the oven were not functioning. That basically reduced the amount of curing time enough that the heavier wheels did not completely cure.
Once that was corrected. the process was started back up.
From that point on, we started testing wheels when we took delivery. We still had an occasional failure that got sent back, but the majority passed and went into use without any more drama.
In this case, the shop just experienced an equipment failure, but after that incident, when I decided to have items powder coated for my personal use, I started looking at different shops and asking questions. What I found is that many of these shops have no clue as to what they are doing. They just spray and bake. Most of them have the oven temperatures right, but will heat small and large parts at the same time and not allow the larger parts enough oven time to totally cure.
Now if you are having lawn chairs or even bike parts like luggage racks done, this is probably not an issue other than that partially cured coating is not going to be as hard as it should be.
Even parts like front wheels may never see an issue. Rear wheels may be a different story.
The bottom line is talk to a shop before hand and ask questions about their process. I also tell them before they start that I will be testing the finished product.
When it comes to masking. Always specify that any machined surface that mates to other parts needs to be masked off. This will not only ensure proper fit at reassembly, but would also prevent the failures we saw on our truck wheels in the event that the coating fails.
As far as testing goes, it is a very simple process. Go to Home Depot or Lowes and pick up a can of MEK solvent. Wet a Qtip and rub the coating rapidly 10 or 12 times. If the coating is properly cured, this will have no effect on the finish. If not, the coating will smear and it needs to be redone.
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