Tempering Oxide Scale Flaking Issue
Tempering Oxide Scale Flaking Issue
(OP)
I'm having an issue where our desired oxide scale is flaking off in our process leaving the product with a spotty oxide scale coating at the finish. Here is some information on our process:
We start by taking the drawn wire and cleaning it in an inline tank to remove drawing lubes and other surface contaminants, then we use an induction heating unit to bring the wire up to temp more quickly, then it runs through a muffle tube furnace with a wet nitrogen/propane atmosphere, followed by an oil quench, then a cold kettle lead bath, water rinse and oil spray before the take up. We are having an issue with one product that is a chrome silicon vanadium composite. The scale is flaking off between the oil quench and the take up after being formed in the muffle furnace. This issue seems to be even worse after a start up from a PM. Any ideas on things to look at that could be causing this to flake off? If you need any specifics please let me know.
We start by taking the drawn wire and cleaning it in an inline tank to remove drawing lubes and other surface contaminants, then we use an induction heating unit to bring the wire up to temp more quickly, then it runs through a muffle tube furnace with a wet nitrogen/propane atmosphere, followed by an oil quench, then a cold kettle lead bath, water rinse and oil spray before the take up. We are having an issue with one product that is a chrome silicon vanadium composite. The scale is flaking off between the oil quench and the take up after being formed in the muffle furnace. This issue seems to be even worse after a start up from a PM. Any ideas on things to look at that could be causing this to flake off? If you need any specifics please let me know.





RE: Tempering Oxide Scale Flaking Issue
rp
RE: Tempering Oxide Scale Flaking Issue
Thanks again
RE: Tempering Oxide Scale Flaking Issue
If they are solvent cleaning they may be diluting the oils, greases, etc. A caustic solution will saponify the oils and greases so there can be 100% removal. A commercially prepared caustic solution will also have additives to aid rinsing.
There are two cultural issues that often come into play in this kind of situation. 1. The practice of using solvents as cleaners has a much better reputation now than it deserves. Most of the really good solvents are now either illegal or so highly regulated that their use is impractical. 2. People play with baths.
A classic industry story has the night shift operator adjusting the pH up to improve performance and the following day shift operator adjusting pH down to improve performance. And so on.
Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
Good engineering starts with a Grainger Catalog.
RE: Tempering Oxide Scale Flaking Issue
At some point it becomes so thick that it is porous and fractures.
You need less moisture with this product.
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Plymouth Tube
RE: Tempering Oxide Scale Flaking Issue
We will also be looking into our cleaning bath solution and trying to make some changes there. I am not very familiar with what we are using in that part of the process, but I will be working with another process engineer on this.