De-stressing metal? machine shop service?

[locry]

i went to machine shop today that offers ceramic coating and other "hitech" services(or so they claim).
Anyway. one of their services is de-stressing engine blocks, heads, whatever, using a table of some sort which vibrates. They say they can read if a particular part is stressed or something and that they can relieve the stress... make sense? i think it has to do with resonance? i really don't know, anybody heard of this service/method?

[leathermang]

Never heard of it...and as Old Blacksmith very skeptical that any of our cast iron objects would need ' de stressing'...
On cast iron objects this is typically done before they are machined....by heating and cooling cycles and often by just curing with time...
Stresses do exist from uneven cooling... but by the time you have used it I do not believe any further service is needed.

[boneheaddoctor]

Destressing metal or castings is not a scam....thats why seasoned (used) engine blocks are preffered to new blocks.....New blocks will shift as the internal stresses are relived.

The usual destressing process is usualy heating them to a certain temp and holding that for a prescribed amount of time and slowly lowered back to abient temp....the process may take days.

I don't remember the specifics but it isn't snake oil or pseudoscience.

It must be done to cast iron which has been welded. to prevent new cracks from forming. But this applies to all types of metal.

[leathermang]

We are not talking about the original casting and destressing process... which more likely takes months ....
I am saying that there is no reason that I can see to take your old block or head to someone for this during a rebuild....

BHD... AND the qustion was about this particular type of ' destressing' the shop is selling.....have you heard of this being used or needed on an already USED block or head ?

[boneheaddoctor]

Originally Posted by leathermang

We are not talking about the original casting and destressing process... which more likely takes months ....
I am saying that there is no reason that I can see to take your old block or head to someone for this during a rebuild....

I agree with that.

[Brian Carlton]

Both of the aforementioned fellows are correct.

When metal is welded or machined there are stresses that build up during the process.

The "stress relieve" process involves heating the part up to a prescribed temperature and then letting it air cool. The piece is allowed to move and thereby relieve the stress.

To bother with "stress relieve" on an old block or head is ridiculous. The process that you have mentioned seems to be complete BS.

[Pete Burton]

like if you go to a shrink........you spend some money and they determine that you need to have stress relief. You can have that stress relieved if you are willing to relieve yourself of some money. How much money, oops I mean stress, do you want removed?

[boneheaddoctor]

Originally Posted by Pete Burton

like if you go to a shrink........you spend some money and they determine that you need to have stress relief. You can have that stress relieved if you are willing to relieve yourself of some money. How much money, oops I mean stress, do you want removed?

Isn't that the service escorts provide?

[leathermang]

" letting it air cool."

Often the item is covered in either sand or vermiculite... which can really stretch out the cooling process....

[Habanero]

When I was kid Dad amazed me by taking 2 pieces of the same metal, heating them up in the forge to the same temperature, then cooling one in a bucket of water and the other in a sand bath. Once cool, he would then proceed to put them in the vise and bend until breaking to show how much of a difference the cooling method made. Of course I was about 5 when he did that, so I didn't understand the chemistry involved, but I still remember it vividly.

[locry]

hmmmm,

so there is some truth to their process, but he didn't say anything about heating and cooling, just a super vibrating machine, possible?

Anyway, when i had my warped cylinderhead(603, no cracks) shaved at a different machine shop, they also filled in all the pitting by TIG welding new aluminum before the machining, now the surface looks like new. would this be a problem in the long run? (I DIDN"T mention this to the guy offering the de-stressing service btw)

[leathermang]

"so there is some truth to their process,"

NO... no one said that on an old block or head which has already been around for years in use powering an automobile that ANY other destressing process sounds like it is needed or worthy of being paid for...

[boneheaddoctor]

Originally Posted by leathermang

"so there is some truth to their process,"

NO... no one said that on an old block or head which has already been around for years in use powering an automobile that ANY other destressing process sounds like it is needed or worthy of being paid for...

Agreed again.....these people want to facilitate seperating you from your money....

[Wes Bender]

Habanero - You've got one smart Dad. Too bad more kids aren't exposed to lessons in physics such as that. My Dad was mechanically inclined and taught me a lot, but it was my high school physics teacher that taught me the most.

[boneheaddoctor]

Originally Posted by Wes Bender

Habanero - You've got one smart Dad. Too bad more kids aren't exposed to lessons in physics such as that. My Dad was mechanically inclined and taught me a lot, but it was my high school physics teacher that taught me the most.

My Father taught me to be as self sufficient as possible. He died of cancer at 65 in 1996.

Welding I learned in Highschool (took COllege Prep curriculum but took Metal Shop as an elective for 4 years)
Taught me to lay brick, do pluming..Work on a car at a very young age (was doing brake jobs at 11)
How to do house wiring. How to fix an oil fired furnace. BasiclyEverything you need to do if you own a house or drive a car.

THe lesson being is the more you know the less you need to spend on others and the harder for someone to screw you if you hire someone else to do the job.