Material sorting 1

[yates]

Several fastener specifications require 100 per cent metal identification on finished parts. This is to prevent material mixups during manufacturing, and is not a chemical composition check but simply a check for the right grade of material.
To my knowledge, the only possible method is by eddy current comparison with a known sample(X-ray fluorescence is out since the check has to be done on finished parts and a lot of finished parts are plated) Does anyone have any experience with such a beast ? Who makes the equipment ? It seems to me, a long time ago, that the precision casting business used 'magnatest' equipment.

 

[Goahead]

Sorting fasteners cannot replace correct procedures designed to keep lots identified and segregated.
XRF and hardness testing can be peformed on 100% of parts just before plating. If already plated, with adequate energy XRF will reveal the material under the plating.
Also Eddy Currents instruments will be influenced by plating.

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

 

[yates]

Goahead, I know that nothing replaces good material tracability and housekeeping. However the spec. does require 100% metal identification. XRF or hardness is not practical on large batches of small fasteners. We currently use eddy current for 100% hardness check (using hardness tested pieces to calibrate) after heat treat, when required by customer, and this is achieved by picking up slight variations in conductivity resulting from structure difference. It would therefore appear theoretically possible to sort alloy types by differentiating between structures, providing of course you have a known sample of the same part in different materials. My question is, does anyone have any practical experience of this ?

 

[EdStainless]

When we ET tubing we are flaw testing in the differential mode. We also run a channel in absolute that we use for 'type check'. If you run a piece of 304 in the annealed condition vs the cold worked condition you can tell. You can also distinguish 304 and 316.

If you were going to use this method I would think htat you would need to strip the plating from some (after calibration) to verify chemistry (XRF) and hardness.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[MOB1]

We used sorting machines which worked on the placement of a coil over a known material and a second coil over an unknown. If they were the same material the display on a CRO was different from that displayed if the material were different.
The machine was called a "DR FOERSTER" and their web site is:

http://www.foerstergroup.de

I would suggest that a NON DESTRUCTIVE TESTING equipment supplier could help.