Passivation is a non-electrolytic process typically using nitric or citric acid which removes free iron from a stainless steel surface. This forms an inert, protective oxide layer that in turn renders the stainless steel more rust-resistant due to lack of iron to react with atmosphere. During machining manufacturing processes, stainless steel parts may have imperfections […]
Why are two rinses often recommended after passivation?
When parts are passivated with citric or nitric acid, the parts themselves, as well as the basket they are in, carry some of the acid into the rinse tank. This “drag out” means that the rinse solution has to be constantly replaced or will simply become more and more acidic over time. The biggest issue […]
What’s the difference in passivation and electropolishing?
As a non-electrolytic process, passivation uses solutions like citric and nitric acids instead of an electrical current used in electropolishing to create a inert oxide layer / film and remove free iron and foreign matter from metal surfaces. Electropolishing, a non-mechanical interactive process, can be used on objects with complex geometries. The electropolishing process uses a combination […]
What’s involved in the passivation validation process?
Within the medical device world there is a need to validate the passivation process. But what does that mean, and how does that work? Validation is the process of insuring that the passivation process you use will reproduce repeatable and predictable results every time a batch of parts is run through the process. By validating the process […]
What is the best method of passivation?
Have you ever noticed that many day-to-day things seem to get divided into two opposing camps? Things like asking what’s the best computer quickly become the PC versus Mac debate. Phones? iPhone versus Android. So, passivation? Yup, nitric versus citric. There are real advantages to each nitric and citric passivation, but that is a topic for other […]
Why are automated systems easier to process validate than manual equipment?
Process control and stability are critical aspects to regulated medical device and aerospace processes. It is important to ensure that a process has input and output variable limits which are defined and fully tested during process design, Equipment Qualification (IQ), Operational Qualification (OQ) and Process Qualification (PQ) validation testing. Setting up a proper DOE (Design […]
What’s the difference between nitric and citric passivation?
Both nitric acid and citric acid are effective in passivating many grades of stainless steel, and both methods are described in the industry standards ASTM A967 and AMS 2700. Citric acid passivation offers the following key differences. Compared to nitric acid passivation, citric acid passivation is: Newer More environmentally friendly Safer. In the past, some manufacturers avoided […]