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Thread: Shot Peening

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    Shot Peening

    Is there a reason why more custom builders are not offering a shot peened finish for their frames? I know IF offers it for their titanium, but why not Black Sheep, Moots, Eriksen, etc.? And couldn't it be a finish choice for steel as well? Unless it's an issue with cost, or there's a hidden risk associated with the process that I'm not familiar with, it seems strange that it wouldn't be a more popular option. I understand there are supposed to be structural/strengthening benefits as well, but on top of that I just think it looks great.

    Thanks!

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    To understand what shot-peening does, take a coat hanger and flex it back and forth until it breaks; before it breaks it will get stiffer (and hot) because the metal hardens from the work. To a point, an increase in hardness results in an increase in tensile strength, balanced out by a loss of ductility. Shot-peening causes the metal at the surface to flow a little bit, and that so the metal gets harder and stronger. Some metals will gain some corrosion resistance also but not enough to skip corrosion control for steel I wouldn't think. Aluminum, shot-peened and done with a clear matte or flat finish, would be a nice change from glossy paint, I think!

    Why bike manufacturers don't do it? No idea. The process is similar to sandblasting, the media is entirely re-usable, and it could easily be automated, so it is a matter of equipment cost and processing time. There is no reason you couldn't have the pieces you've got peened, but determining what size shot, what air pressure, where, and how long is a matter of experimenting to get the best results. It is very common in aerospace (my field of expertise) and would be a great value-added feature for the manufacturers if they can make it work economically. My 0.02. Jim

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    Thanks for the reply! I wouldn't expect any of the smaller builders to purchase the equipment, perhaps some larger ones could more easily afford it, but I would think that they could send frames out for shot-peening in the same way they are sent out for paint. That's why I don't understand why it's not more common.

    I've seen various types of metals shot-peened for architectural applications such as decorative wall paneling, so at the very least it offers another aesthetic for people that don't want their bikes painted.

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    in short......shot-peen relieves stress(and adds a kind of rough matte finish)........it's like a spa day for parts.....a little massage if you will.
    i too am in the aerospace industry and send out helicopter hydraulic pistons out for shot-peen after they come back from having the chrome striped, because of the stress that they went through in the strip prosses.

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    Folks at IF initially conceived of shot peening their Ti frames for aesthetics, then realized that they might also gain some structural benefit as well. I am going to guess that in the long run shot peening the average frame is going to yeild as much benefit as washing your car for better aerodynamics.

    Though I could be wrong.
    Quote Originally Posted by banks
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    Quote Originally Posted by IF52
    Folks at IF initially conceived of shot peening their Ti frames for aesthetics, then realized that they might also gain some structural benefit as well. I am going to guess that in the long run shot peening the average frame is going to yeild as much benefit as washing your car for better aerodynamics.

    Though I could be wrong.
    It depends on the material. Anything that will work-harden can benefit, and being that decent bikes are usually made of similar materials to modern aircraft (and cost about as much for parts ) similar engineering methods work. Now a department store bike frame made of low-alloy steel will look a little nicer, but it probably won't be any stronger. I don't have any reference material for which materials work-harden usefully, but there is always Google for that, right? Jim

  7. #7
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    Quote Originally Posted by IF52
    Folks at IF initially conceived of shot peening their Ti frames for aesthetics, then realized that they might also gain some structural benefit as well.
    I was the one who educated Mr. Matty Bracken about that as he had no clue when they had the first Ti frame @ Interbike.

    Look into the auto racing industry, shot peening is a big deal.
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.

  8. #8
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    Quote Originally Posted by banks
    I was the one who educated Mr. Matty Bracken about that as he had no clue when they had the first Ti frame @ Interbike.
    Nice.

    Quote Originally Posted by banks
    Look into the auto racing industry, shot peening is a big deal.
    Yeah, everything internal under stress like cranks and rods gets shot peened. But I think on a dollar per value basis on a bike you just won't see enough of a benefit. IF realized, or was informed rather, that there was a benefit to shot peening after the fact. Do they actually engineer their peening or is it more randon with the first goal being a unique look?
    Quote Originally Posted by banks
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    Quote Originally Posted by IF52
    the first goal being a unique look?
    yup.
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.

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    Sorry, but I still don't understand why IF seem to be the only guys offering it as a finish option... even if it is just for aesthetics.

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    I know my Eriksen has a bead blast which is not as abrasive as the IF bike, but wander if there is a similar effect. (Bead blasting and shot peening are similar but different, but not sure how different they would affect the frame's structure). Banks, you would know what I mean. Is what Kent does just cosmetic?

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    Quote Originally Posted by Treybiker
    I know my Eriksen has a bead blast which is not as abrasive as the IF bike, but wander if there is a similar effect. (Bead blasting and shot peening are similar but different, but not sure how different they would affect the frame's structure). Banks, you would know what I mean. Is what Kent does just cosmetic?
    For all intents & purposes the action is the same. The media and force makes the difference.

    Kents frames get glass bead blasted to clean up the frame, cosmetic. There isn't enough force nor is the media big enough to cold work the tubing.

    For Ti, I prefer the painstakingly dirty & long process of red-green-white Scotch Brite pads, for my finish.
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.

  13. #13
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    any point in having a "brushed" Ti frame shot peened ?

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    Quote Originally Posted by willyrick
    any point in having a "brushed" Ti frame shot peened ?

    It couldn't hurt, but paying IF to do that may be expensive.

    IMHO the brushed finish is the best as you can always touch it up.
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.

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