specify x-ray class requirement on castings

[pparent]

We are designers of castings (investment, permanent mold) and we are looking for information to base our inspection criterias for the ASTM E155 and ASTM E192. Would buy handbook or specif. that would explain differences between grades and relation with allowable defect sizes etc...

Don't want to specify grade D everywhere neither grade A that nobody will be able to produce...


Thanks for the info,

PP

 

[metengr]

We are designers of castings (investment, permanent mold) and we are looking for information to base our inspection criterias for the ASTM E155 and ASTM E192.

What you need to do is to evaluate purchasing a set of reference radiographs from ASTM pertaining to the wall thickness range of your castings. These reference radiographs contain samples of various casting defects rated by severity levels. They do NOT provide acceptance criteria, that is left up to the purchaser of the castings.

 

[Goahead]

If you can analyse the stresses under normal operation you may be able to identify the zones of maximum stress.
Then you can specify that in those zones the defects be absent or minimal while elsewhere somewhat larger defects would still be acceptable.
If the parts are critical, all of them are x-rayed.
If not so critical only a percentage is tested, but then the process must be monitored to make sure it does not run away.

http://www.welding-advisers.com/

 

[arunmrao]

Ideally involve the casting manufacturer and an independent testing laboratory to draw the specs. If a component needs to be redesigned or modified please accept the suggestion and incorporate them. Based on your service conditions you can define the level and type of defects acceptable. The choice is never easy,but on a first instance specify level 2 defects as acceptable. Unless you go for aerospace or nuclear applications you might need to specify NSD(no significant defects) as acceptable. But be aware it is never too easy .

 

[horsetrainer]

pparent,

Specifying defect levels in castings is never easy with most instances involving some physical test such as leak testing or pressure testing. For example pump housing castings are pressure checked first at 100% until a level of comfort is obtained then dropped to some lower level there after. X-ray inspection is subjective and specific to individual x-ray units being used and the eyes of the inspector. We have seen parts that have little if any in the way of x-ray detectable defects leak. Sometimes physically breaking the casting (Aluminum) is a test used to see porosity, shrinkage, oxides for example (certainly not NDT however).

Mike

 

[arunmrao]

horsetrainer,
you touched a raw nerve of the foundryman. Yes ,a radiographically sound casting need not be hydraulically sound. The casting might start sweating when tested.Destructive testing is not always possible eg large castings.

 

[horsetrainer]

arunmrao,

I reckon that's why casting is still part art form.

 

[arunmrao]

A dying art for that matter. My generation may be the last to work in a foundry.

 

[deanc]

http://www.foundry.elkem.com/hits/i...u?readform&id=foundryeng&full=full&lo=konsern

Great site......Customer assistance....Tech Info.

 

[domettim]

I believe ASME if you are designing to that standard has details as to what is acceptable based on application and required design FS.

Great site Deanc. Arunmrao you are telling on your age now. There is still hope. One large university Virginia Tech is working on constructing a foundry for use in it's Material Science Department. Anyone interested in more information can contact me at ttrump@dom-met.com

 

[horsetrainer]

There are several universities doing the same. Even smaller universities such as Wright State University in Dayton Oh. that is working on flow modeling programs for both liquid and Semi Solid Casting that look quite promising. One thing though, you just can't see inside the die as the part is being cast.

domettim, I believe training and experieince is the key, there are hundreds of thousands of different parts to cast. all of them with different characteristics and specifications. It takes experienced people such as arunmrao to teach the rookies.

 

[tripleZ]

VT is setting up a foundry? I didn't think I had been away that long! There wouldn't currently be any research going on in the powder metallurgy field in Blacksburg by chance???

Not that I need to add another grad degree to my schedule...at least not yet. =) Thanks for the heads up Dommetim.