Sintered Metal Machined Parts Rust Removal Methods

[Ron Rompen]

I have been assigned a project to:
i) elminate or minimize the amount of corroded parts we have
ii) develop an effective method of reworking lightly corroded parts.

Our parts are powdered metal which is then sintered and machined, washed and rinsed with an RP, and then shipped to the customer. During the recent heat waves in SW Ontario, we have had a lot of internal fallout for rust on the machined surfaces.

I have several ideas on how to reduce the amount of corrosion that occurs, but I am still developing ideas for reworking parts.

Does anyone else here have any experience or knowedge of the following processes (when used as a method for removing light surface rust)

1) CO2 (dry ice) blasting
2) Soda blasting
3) Ultrasonic cleaning

All 3 of these are possible methods that I am looking at, and I have a sales rep from a supplier visiting me next week. However, I already know how well he is going to say it works - I would like to hear from people who have actually USED the process, to see what they think.

Thanks

 

[Jen Kirley]

Re: Rust Removal Methods

What quantity/volume are you dealing with?

 

[normzone]

You might do some searches for the methods you reference, and others, at the Moto Guzzi forum. There are some tales there of successes and failures.

https://wildguzzi.com/forum/index.php?board=1.0

 

[Marc]

... During the recent heat waves in SW Ontario, we have had a lot of internal fallout for rust on the machined surfaces...

Somewhat Probably more a function of the humidity than heat. Aircraft_boneyard

Had a similar issue a number of years back when a switch was made to transportation by rail to Mexico. The company ended up scrapping one heck of a lot of parts and ($$$) individually wrapping each part in a rust inhibiting paper (I forget what the brand, etc. was).

 

[ncwalker]

There is a product called Naval Jelly that works miracles.

Of the others you listed, I would think soda washing would be the best.

 

[RCH2016]

I just recently saw a video of a new technology that uses a laser to remove rust. It seemed to work pretty quickly, but the tool was a little expensive.

 

[1010011010]

For prevention purposes you could consider using VCI (Volatile Corrosion Inhibitor) products, e.g. from Cortec Corp.

For overseas shipments and storage of up to 2 years in Shanghai (hot and humid summers by the sea) we use Cortec VpCI-369 to protect our machining parts. However, that stuff has an almost waxy consistency and needs to be cleaned off before use.

If you don't need the hardcore version, VCI papers and/or foils might help. They emit VCI particles that form a thin film on the surface of the part.

 

[Ron Rompen]

I just recently saw a video of a new technology that uses a laser to remove rust. It seemed to work pretty quickly, but the tool was a little expensive.

Yes, I watched that video as well - very impressive, but as you pointed out, also extremely expensive.

 

[Ron Rompen]

Thanks to everyone who has responded with suggestions. To share a little more information on our processes:

1) We do apply a Rust Inhibitor as the final process step prior to packaging. OEM requirements prevent us from using any kind of grease or similar product which would require removal prior to use.
2) Volume of parts currently rejected is not extremely high, however it is an added cost which we are trying to recoup.
3) Wrapping parts individually in VCI paper is also not acceptable to our customers (and the cost of doing so would be ~ $0.25/pc). We do line our returnable dunnage with VCI (either paper or plastic) but since the dunnage is not sealed airtight, it cannot be 100% effective.