Nondestructive testing of aluminum.

[Ulu]

Do you do it?

I’ve had a Trek aluminum BMX frame hanging over a pan now for some weeks, because I haven’t finished stripping the paint off.

Today, I saw this vid on easy Nondestructive testing of aluminum. He shows how to detect any cracks with a dye & developer.

(Caution: This guy is not child safe. Lots of Canadian vulgarity. )



Anyhow I didn’t know how to check that aluminum frame that I picked up, and it appears to have had some possibility of damage, so I’m going to try this method.

Or something similar.

(And remember to keep your grubby paws off the dump valve until you check the hose clamp.)

 

[Captain Awesome]

That method will only allow you to see cracks that have migrated all the way to the surface. The only experience I have with NDT for aluminum is ultrasonic and eddy current

In many cases the dreaded "creak" when ridden is a good auditory signal for starting issues. Hard to track down and isolate though

 

[Karate Chicken Industries]

In many cases the dreaded "creak" when ridden is a good auditory signal for starting issues. Hard to track down and isolate though

Creak to me means time for a new frame.

 

[MattiThundrrr]

I use auditory testing. The fingernail flick can help you assess a frame quickly. I check a few areas to hear that soda can "ping". If it's a full thud or a weird buzz/rattle, time for a closer look.

 

[Kevin B]

I remember reading in the early 70s in the old Car Craft magazine about racing engine machinists employing the Magnaflux method to inspect rods, pistons and etc.

 

[Ulu]

Well this bike was stripped when I got it so there was never a chance to ride it.

But the more I clean it the better it looks and all the welding looks primo.

When I get the frame stripped and the cups out I will definitely give it a good ring to see if it sounds solid or cracked.

 

[Ulu]

I remember reading in the early 70s in the old Car Craft magazine about racing engine machinists employing the Magnaflux method to inspect rods, pistons and etc.

Well the paint is not off yet completely, but I hung it with string, gave it a rap with a tap hammer, and it sounds really solid. I checked it in several places and it sounds good.

My only dilemma is, “will I have time to build a contest-worthy bicycle?”

 

[M0nster]

Looking for an NDT facility in USA to examine an aluminum frame. Thanks

That method will only allow you to see cracks that have migrated all the way to the surface. The only experience I have with NDT for aluminum is ultrasonic and eddy current

Need to get an aluminum frame inspected, looking for a US company that will do this. Contacted a local company, no response.

Any links/contact info for relevant company are appreciated.

 

[ingola]

I ride it pound the crap out it till breaks. When it snaps tested. All aluminum will get brittle over time unless they are visible I don't worry about it.

 

[Tallbikeman]

I went through a steel is real phase and looked at all the problems with aluminum and carbon fiber. I have broken two steel frames both made by Worksman. Both breaks were on the seat post tube. One was very poor brazing on the bottom bracket lug fitting for the seat post tube and the other was a complete break at the brazed on chain guard fitting. Neither break harmed me, the bikes just took to riding funny so I looked them over and found the breaks. I have friends that are over 200 lbs, much younger, riding both aluminum road and MTB frames of good quality early 2000's. These friends broke these frames pretty regularly. Mostly lower bearing area on the head tube and bottom bracket breaks. I don't know anyone that has broken a carbon fiber frame or fork because I don't ride with that crowd anymore. What I found out was that aluminum tends to fail quickly or even catastrophically. Carbon fiber like wise. Aluminum can be tested with the methods mentioned above. Carbon fiber can spall to the interior of the tubes and one would never know it. So they CAT scan frames to really know if there is any interior damage. I would approach both aluminum and carbon fiber warily. Carbon Fiber is a plastic and is damaged by sunlight. Over time the sun will gradually kill your resin holding the carbon fiber. UV paint really helps in this regard but if they get enough sun I'm sure they will probably end up much like an old fiberglass boat hull. All the foreign manufacturers of aluminum and carbon fiber bicycle frames and forks are set up in such a way that you cannot sue them for inferior or incompetently built frames and forks that have harmed you.

 

[Ulu]

Well I rode the assembled bicycle, and it is silent, so I will assume that it’s not cracked anywhere that I cannot see.

I’m not doing any hard-core riding here. We’re just going around the neighborhood for exercise and the pavement is very nice.

I have a feeling this will not be my last aluminum bicycle. I have been trying to put my wife into a new one, but she won’t give up the steel Nishiki.

 

[Tallbikeman]

My wife bought an older Trek hybrid aluminum frame bike from the early 2000's and it has been a very good bicycle. I went with her and looked the bike over real well because of their reputation for cracking before buying it. It has held up nicely for many thousands of miles.

 

[Ulu]

Mine had never been ridden by anybody over 12 years old, as far as I could tell. But it hadn’t been maintained either.

I think I got lucky because there is a spot in the bottom bracket where they had to machine away a lot. I think with anybody athletic & 160 lbs, it would’ve broken long ago.

 

[outskirtscustoms]

Not sure if it would work on a bicycle frame or not however racing teams back in the day used to use compressed air inside the frame any pressure drop would indicate a crack I don't know if you could seal the frame somehow with a few freeze plugs in the bottom bracket seat tube and steer tube then pump in some compressed air and see what happens.

 

[axeman88]

I worked briefly for a testing company as a summer job years ago.

The Magnaflux method relies on the fact that, in ferrous materials, any crack will result in opposite polarity faces on the two sides of the crack, if the material is magnetized. The parts to be tested were subjected to brief powerful current, then dipped in the magnaflux dye solution. The luminescent dye in the solution would be attracted to the magnetic poles on any cracks, then show up under ultraviolet light.

There was at that time, a spray that was supposed to do the same for aluminum parts, but I don't know how that worked, perhaps some surface tension mechanism?

Seems like one could use the same method used for finding faults in tires, ... cork up openings, pump in air and look for bubbles under water in a kiddie pool. Nobody said it would be easy.