Letter 8037

Cleaning of stainless steel - medical device implants 

+

Technical Inquiry:

A standard process is to use ultrasonics and subsequent acid pickling baths to remove the oxides/slag from 316L stainless steel in a post laser cutting operations. Laser cut parts leave a highly metallic slag and characterization shows pure metal, and various oxides of Cr, Ni, Mo, and Fe. Xray diffraction and SEM analysis also exhibits some glassy amorphous compounds. Hydroflouric (HF) acid is very effective in attacking the oxides but is a major political issue and the amorphous material requires high concentrations to remove.

I am looking for input from chemical manufacturers or consultants who can explain the possibilities of using complexed acids such as fluoboric or fluosilicic that are effective but less dangerous. I am looking to understand the mechanisms of these complexes as input into designed experimentation based on the character of the oxides. This input would be invaluable to the medical device industry as we try to simplify processing with major efforts towards removing sonics, electolytic, and highly aggressive acid pickling operations.

Thank you

Scott Larson
- St Paul, MN, USA

Hi,
I'm useing EP process for ss316 tubes.
The EP bath contains

• 40% H3PO4 (85%)
• 50% Glycerol
• 10% H20
  

I close the bath every evning after i finsh my work.

Its working very good so far, but how can i keep it stable?
how often should i change the bath?

Thanks,

Amir S.

Amir Shal
student - USA