The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Post passivation operations

We are a manufacturing machine shop that produces surgical tools and instrumentation. Currently we are producing a tool that has an outer sheath and inner shaft that has a tip welded on during the last operations and then glass blasted. Before the weld all parts were passivated separately. After the finial assembly the tool traps nitric acid between the sheath and shaft causing accelerated rusting. Are there any appropriate operations that can take place like glass blasting, after an initial passivation?

Thank you,

Kevin Dodd
Machine Shop - Round Rock, Texas, United States
2004

---

I'm trying to answer your question with more questions to help you find the answer yourself.

1) When you say you are passivating, doesn't that mean that you are neutralizing the parts with Na OH or a neutral soap after a Nitric wash as well?

2)Why can't you use a glue in between the sheath and shaft?

3)I can think of only your flux used during welding bringing in acid again which causes rusting. Is that possible?

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2004