First of all – this is not a post, where I´m going to complain about guy´s who drive replica wheels on their car. To be honest, in the past I did but I realized, that punishing the people because of their wheels is not the right way. Everyone is free to buy stuff that he/she can effort or like.
Because of that, I´m going to use terms like “replica” or “kock-off” instead of “fake”, because in my opinion fake is a handicapped word.
Since I´m in the JDM sports car scene, there are people who like real or replica wheels. Some people argument, that the high priced wheels are representing quality and durability. The other reply that replica wheels are just the same and are cheaper, because the manufacturers are doing less advertising. Let´s find it out!
Are they right with that statement?
As some of you may know I´ve studied mechanical engineering with main focus on automotive engineering. During my degree I´ve spent a lot of time analyzing typical automotive products like engine, exhaust and suspension parts. No worries the list is a bit longer, but hopefully in the future we will come back to this. 😉
During manufacturing engineering and construction lectures, I´ve found myself thinking about automotive products like wheels. I´ve took my time and tried to figure out how wheels are manufactured by Rays, Volk, Work, SSR, BBS and other high priced manufacturers with the ability to high quality.
I exactly remember that moment, when I went to my professor after manufacturing engineering lecture, where we spoke about casting and forging. In that lecture we spoke about the pros and cons in relation to casting products. Of course you have to know the application area of the products you develop, because they give you the information you need to know choosing the right production method. In any case we spoke about high performance wheels, which I´ve mentioned before. Luckily I had the chance to show him a production video made by Rays wheels.
After he saw this video he was highly impressed of the precision and the high quality. But he also told me, that you have to look after the cost. Most people today want to buy affordable products and because of that casting wheels are also okay. One of the differences are for example, that wheels which are forged can handle high stress like an impact without cracking. The reason why they do not crack, is the heat treatment during the forging process. Furthermore they are light, because of the inner atom structure of the material.
When you want to understand why casted wheels are cracking under stress, you need to know a little bit about material science. For that reason, I´ve concluded some facts about casted and forged blocks.
As you can see on figure 1, a casted and milled piece is compared to a single billet. But what does the lines mean? When you examine the pieces, you will find out, that forged materials can handle more stress. The reason why they can do this, can be shown as fiber courses. Compared to the casted & milled piece, the forged piece have the ability t follow the lines around the corner, so there won´t appear stress peaks. Furthermore the layers on the forged block are not able to slide on each other, which increase the shear forces you need to deform the block.
Figure 1: Fiber course of casted and milled compared to forged billet
When you take a closer look to figure 2, you will find even more advantages for forged materials, like the closer microstructure. The closer the structure is, the higher your material can resist and the higher is the coherence.
Figure 2: Microstructure of casted and forged materials
Both facts make it happen, that forged wheels do not crack, but deform their self under high stress like an impact.
Here you can see the difference:
But there is one thing, that makes me very angry and have to be mentioned
A fact is, that a lot of manufacturers are selling forged wheels, that are made of forged billet. But as you can think, those billet´s get milled and turned to get the final product. The result is, that they lose the ability to transport the stress through the material over the curved fiber courses.
But why using forged billets in that case?
I guess they like to show themselves like a high quality company. Of course those forged billets have the advantage to have a tighter microstructure, but they do not have a fiber course, because the product is milled and/or turned.
As a conclusion you can say, that all those advantages for the forge wheels, are the disadvantages for casting wheels. As I mentioned before, forged wheels can be made completely though the forging process, but also can be made by billets. Those billets get milled and/or turned to the final product, but lose their main advantages.
But what you definitely can claim, is that the casting process is way more affordable.
What are your thoughts? Let us know in the comments!
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