Anyone ever heard this? A guy at my work said that he had a set of wheels blasted and painted and the sandblasting ruined them because it stress relieved them… Anyone else ever hear of this? Personally, i think that the wheels were bad before he blasted them, and that it wasn’t until he tried to balance them that he found that they were out…
lafengas would know… he told me that when i wanted to do my stock stook wheels abck in the day that sandblasting will “weaken the wheels”
Never heard that one before… I could see blasting causing metal to distort on body panels and thinner metals, never head it about wheels though :shrug:
Interesting. Never heard that before. Subscribing to see answer from someone who knows.
Where they cast or forged wheels?
Are they steel, aluminum, magnesium, etc?
There are a couple ways to stress relieve metal that has been FORGED, EXTRUDED, WELDED, or some other high heat/deformation combination. Bead blasting and long term heating at low temperatures, below the alloy’s ‘critical’ range (above this temp is called Normalizing or Annealing) are common ways to stabilize structures.
Stress relieving can cause warping on light gauge material … heavier structural metal such as wheels won’t (for disclaimer purposes… “shouldn’t”) warp.
Maybe he assuming the sandblasting warped them.
Did he heat the wheels to strip them or did he use any harsh chemicals, etc?
What about powdercoating weakening rims? is this only true if the heat used to cure the powdercoat is too high of a temperature. I am interested in learning more about this…
Jeller
I don’t think powdercoat would have a big affect because the temps are not high enough for long enough.
The 24 hours of Daytona would probably be worse.
The original quality of the wheel would be another factor.
i may have them anodized instead of powdercoated, but that still leaves the blasting question… i was going to do them in the hand blaster, but i am reading that media such as walnut shells may be a better option… anyone know a blasting shop?
Clear anodize?
Hard anodize?
black.
Keep in mind that that the coloring is organic and it will fade.
It will also be affected by soaps with ANY acid in them.
We blast with Baking Soda that will not harm the rim at all. Soda blasting is what the Military uses for depainting of the wheels on their planes.
powdercoat!
who is we? and how much?
good to know, thanks!
It should not warp a wheel unless there is a manufacturing flaw in the wheel, which than i would rather fuck them up while blasting them than be driving on it and have it crack
sandblasting can be pretty harsh, i know it’s apples and oranges, but i have seen 3/8 stainless steel plate warped by a blaster…
sandblasting can realign surface grain structures and will cause VERY non-uniform heat concentrations.
[QUOTE=newman]who is we? and how much?
We as in the place I work.
Let’s rule out powdercoating as having anything to do with weakening rims. We know it’s not the powdercoat itself, it’s the temperature the metal is heated to. You can find exact critical temperatures for every rim alloy, both aluminum and steel.
I’ll try breaking it down.
What Process “SOFTENS” the metal? The Answer is Annealing. You can’t say ‘weaker’ because softer doesn’t mean weaker. For instance, hardened steels are very hard, but brittle. You can break them with impact.
In order to determine the Annealing temperature you need to look at it’s TTT Diagram (Transformation, Time, and Temperature) to determine the Critical temperature. At this point, you’re looking at the metal under a microscope and seeing how the actual grain structure is affected.
Once you find the Critical temperature of the specific alloy, it should be heated about 100°F (rule of thumb) above the critical point for a period of time (in hours). This changes the grain structure of the metal (to what’s called an austenitic structure) Once this critical temperature reached for a period of time, it is then air cooled to slowly bring it down to room temperature. That’s the ‘generic’ annealing process.
Now…to put things in prespective. Carbon steels with a low carbon content ( less then .12% carbon, i.e. tool steels) their critical temperature is 1600°F to 1700°F. The higher the carbon content, the lower the critical point… as low as 1400°F for the lowest critical point temperature.
I don’t know the specifics for aluminum off-hand. What you would do is find an aluminum alloy, find it’s TTT diagram and find the critical temperature. I believe the annealing range for aluminum is about 700°F - 1200°F
Powdercoating oven is typically 300°F - 500°F