WILWOOD BRINGS TYPE III MILITARY-SPEC HARD ANODIZING HOME
Street Trucks : Thank you, Michael and Phil, for taking time out of your busy schedules to give our readers better insight into Wilwood’s in-house hard-anodizing production. Can you please let our readers know who you are and your role with the company?
Phil Dunne : I’m a process engineer here at Wilwood, and I come from a long finishing background. I’ve worked on everything from consumer electronics to things that blow up for the military.
Michael Hamrick : I’ve been in the automotive aftermarket industry now for 25 years and have spent 16 of those years with Wilwood. When I started here, Wilwood catered mainly to racing-based parts, that has transformed more into the street-performance market now, but our roots are still in racing products.
Impressive! Glad to meet you both. For some of our readers who don’t know exactly what anodizing is, could you give us your definition?
Anodizing is all about abrasion resistance. Aluminum oxide is a really hard ceramic. When we apply electricity to it in the chemical bath, the aluminum oxide migrates up to the top surface and creates a buildup on the part. The thing that makes anodizing really unique to other finishes is that when it’s migrating through, it also builds up that same density, mirroring its growth on the outside, on the inside. It’s integral to the part, as opposed to a powder coat, which is just on top of the part, so adhesion is never an issue.
Can you explain where the Type III Mil-spec hard anodizing fits into this process?
The Type III really is a step above the Type II, which is usually offered in an assortment of pretty color finishes. Either one can be dyed black, but generally you’ll see Type II in red, blue or clear. The difference there is that when the aluminum oxide grows out, it grows out in a honeycomb shape.
So, when we’re looking at the Type III anodize, the diameter of the pores in the honeycomb are very small and tight, and you have a lot more material there. The Type II has much larger pores in that honeycomb, which is why you are able to get the dye into it.
Phil had a great way of explaining it with straws as an example that really hits home when thinking about the difference between the two. Could you go over that one more time, Phil?
Sure, think of a regular drinking straw and the slim, tall red bar straws. If I held a group of straws from Mcdonald’s in my hand tightly, and we looked at the top of them, they’d be about 2 inches tall, and the straws would have larger diameter holes; this would be the Type II anodize. Type III would look more like a group of the bar straws with much smaller diameters, and many more of these straws are able to take up the same space as the Mcdonald’s straws. It’s that extra material that gives Type III better abrasion resistance.
That makes a lot of sense. Is the Type III able to be dyed at all?
A natural gray color results in the Type III anodizing, because—going back to the straw comparison—the Type III straws are twice as tall as the Type II, so none of the light is making its way in there, allowing the aluminum to reflect out with that clear white look. If a custom color is desired for Type III calipers, we do offer a powder coat that would cover the anodize finish, leaving the customer with a nice cosmetic appearance on top of the Mil-spec abrasion resistance of the moving parts.
It’s good to know that there is an option to have the best of both worlds when ordering product. Wilwood has offered the Type III for some time now, right?
Wilwood has always offered Type II anodize on its brake calipers, but as far as the Type III hard anodize, most of the parts offered were exclusively for race applications. We’ve always had a strong network of