Any Tips for Improving Mixer Blade Life? 2

[Cullet]

Hello,

My company uses high-shear mixers to batch ceramic slurries and have been having an issue with the mixers blades wearing away because of the abrasive nature of the powders. I am looking into methods to improve the life of these blades and was considering a Boron Nitride and/or Tungsten Carbide coating. The mixer blades are made of 304 SS and are typically worn away after 7-10 batching cycles. Has anyone had any experience with this issue and can offer a simple solution(s)?

Thanks,
Steve

 

[EdStainless]

Do they need to be SS?
If so then move to a PH stainless or 440 and look at coating.
There are two types of coatings; ones that are implanted or reacted with the alloy, or ones that are applied.
The real question is what is the failure mode when it starts to go away. For this reason I would prefer implanted or reacted treatments.
Things such as ion nitriding or TiC are part of the material and will eventually wear away but there is no layer to flake off.

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Plymouth Tube

 

[dgallup]

How are the made now? I suspect they are stamped or cold worked to get a complex shape. You will need a material that can accommodate the same process. 304 is quite soft unless it is highly cold worked. Lots of harder materials or hard coatings out there.

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[mfgenggear]

cullet

I think dgallup is on it.
why not coat the blade with chrome or nickel?


Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[EdStainless]

1. The 304 isn't strong enough to support a hard coating
2. When there is local failure you would undercut the coating and could result in flakes in the process.

PH stainless is commonly used for mixer blades. You form and weld annealed and then age harden.
If you want you can surface treat at the aging temp.

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Plymouth Tube

 

[mfgenggear]

ed

thanks for the correction.

Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[metengr]

Before you decide spend a little time reviewing the information below

http://www.hindawi.com/journals/ijce/2012/171838/

 

[tomwalz]

We can help with Carbide or Stellite Hardfacing.

We can also help with failure analysis. One way to start is to determine how it is wearing. Are there odd, exceptionally hard particles in the slurry (e.g. quartz in gypsum). Is the pH correct?

In any case hardfacing of any sort is of only marginal utility if the underlying material will wear away. Improve the underlying material to establish a performance base line then try hardfacing.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[dgallup]

Good find metengr

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[micalbrch]

What about hard rubber lining?

 

[Cullet]

Thanks for all of the feedback. We do not manufacture these mixer blades in-house but rather buy them from the manufacturer of the mixer. They look like circular saw blades with alternating teeth turned in opposite directions. You can see what they look like on the manufacturer's website at:

http://www.morehousecowles.com/products/parts/impellers-morehouse.html

The manufacuture only offers them in 304 and 316 SS but also offers a WC coated version. The failure mode is that the teeth start to wear down becoming thinner and losing their impact angle. The blades slowly convert from a shearing motion to a cutting motion and the particle size of the slurry is affected. If pictures of a worn down blade compared to a new blade would help, let me know and I'll post some.

Also, contamination from any erosion or flaked coatings could be an issue as we are dealing with electro-ceramics.

Regards,
Steve

 

[dgallup]

Since they offer a WC coated version that would be my first choice to try. You already have eroded 304 SS in your batch. The amount of WC would be miniscule compared to the 304.

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