streetlegal

is hyrdroforming strong ? doesnt the wall thickness at the hydroformed area get reduced?

MattBeaty

Hydroforming is a strong process. Any process that forms metal, such as extrusion or using presses, would thin the metal. This is most likely taken into account when the part is designed. The real benefit of hydroforming that it can easily make complex shapes that would generally require several parts welded together to achieve.

trekkie820

Hydroforming is a cutting process, the wall thickness is not effected. The nice thing about it is that it doesn't use heat and the same thing that MattBeaty said.

dminor 

Actually it is not a cutting process at all; it is a forming process that uses liquid pressure to bend the material. It is used to press complex shapes in a single pass instead of going through a multi-step process with metal-to metal dies. There may be microscopic thinning at some bend/stretch points - - that's why you will see strengthening ribs formed in at strategic places, etc. Also keep in mind that many aluminum alloys do what is called "work-hardening" when they are formed. In other words, the metal actually changes in hardness in the bending process. Hydroformed parts often are stronger than if they were created from individual tubes.

trekkie820

Hmm, interesting. I always see them using that Flowjet machine on American Chopper and figured that it was the only water pressure metal working device. I just assumed (silly me) that my metal manufactuing class would cover such a thing. Thanks for the info!

dminor 

It is funny that they don't. It's becoming big stuff as more things (especially automotive) are going toward formed-sheet to save weight. Here is an excellent resource that I found about the whole process: AZoM.
Also, since you're a student of metals, you'll probably find Ron Fournier's Metal Fabricator's Handbook interesting. Even though it focuses on race car metal fabbing, it has a lot of good info on aluminum and tubing properties and fabrication. You can find it on Amazon here. I have a copy at home that I refer to frequently.

Brian

That's not hydroforming. And they generally use heated oil for the hydroforming process, not water.

iamlucky13

That's waterjet cutting, which does an extremely clean cut unless you start getting into really thick pieces.

MattBeaty

One of my friends dad owns a water jet machine. It really is amazing how fast it can cut a clean edge. Their machine can handle up to 6 inch thick steel! Here is a little trinket he made for me, it was only cut on a medium quality setting, but it gives you an indication of the cuts that can be made. The part is out of .500 aluminum. The finish quality looks very much like sand blasted metal, because the water alone can not cut the material, it acts as a carrier for garnet powder, which is the abrasive that actually cuts the material.

gurp13

When I was buying my Stumpjumper FSR, the mechanic that was helping me was saying that they hydroformed the frame on that model. Any idea if that's true? I went looking for info on the M4 alloy frame and found very little on the 'net.

skiahh

The frame of my 3/4 ton pickup is hydroformed. I'd say it's fairly strong....

As for water cutting, I have a tailhook from an EA-6B that I got cut in half lengthwise. These things stop a 45,000 # jet flying at 150 MPH in just a few hundred feet. Pretty amazing that water can cut it clean.

scrublover

hydroforming works well. some of the walls may be thinner, but that is part of the overall design. the extra stiffness of the final shape achieved (or whatever the designer is planning) makes up for it. as well as much hydroforming is done to increase the available surface area for a weld, so you end up with maybe a thinner tube, but a larger weld area spreading the loads out over a greater surface area.

just because a tube is thicker doesn't always mean it's stronger.

streetlegal

hydroforming uses either water or oil. its a process where water/oil is passed through the tube in the die at more than 25000 psi.