atomizer (liquid to powder)

[mmitpwdba]

Need some material suggestions for an atomizer that changes a liquid into a powder for the food industry.

Current material is a 400 series stainless heat treated to 55-60 Rc.

This is a multiple part assembly that is experiencing extremely abrasive wear.

Machinability is also a concern.

Any help would be greatly appreciated.

Thanks,

Jeff

 

[butelja]

Is this a nozzle in a spray dryer, or something else?

 

[mmitpwdba]

Yes, I believe it is called a nozzle.

It spins at approx. 4000 RPM

The liquid originally processed is now more of a slurry and is now causing severe wear to the original design.

Jeff

 

[mmitpwdba]

Further clarification...

The assembly is different sized vaned parts that fit together.

And it spins at 14,000 RPM's not 4000

Jeff

 

[TVP]

If you need a corrosion resistant/stainless steel with that type of hardness, there are only a couple of developmental alloys that are better than 440C stainless: one is called Cronidur 30 and the other is Ferrium CS61. Cronidur 30 is a patented composition of VSG in Germany (I do not believe they have a website), and it's only commercial use is in high-performance bearings (FAG and Barden). Check out this website for more info:

http://www.bardenbearings.co.uk/index.cfm?articleid=606

The other alloy, Ferrium CS61 is a patented composition developed by Questek Innovations in Evanston, IL, USA (

http://www.questek.com/

). It can develop an outstanding combination of strength, toughness, and corrosion resistance. Last I knew, this was only a developmental alloy, with no commercial producers currently making it.

Having said all of this, do you require the entire component to be 55-60 HRC? Have you considered using an alloy steel and then coating it (ceramic/metal co-deposition by HVOF, chromium plating, etc.)? Or using an alloy steel and using a diffusion process like salt bath nitriding (ferritic nitrocarburizing) or one of the nitriding processes (gas, liquid, plasma/ion). Any of these methods would produce a part with the necessary surface hardness, but the core hardness may not be the same. Perhaps if you provide some additional details on the performance requirements (forces, temperature, corrosion, etc.) the rest of us on the forum can offer appropriate suggestions.

 

[mmitpwdba]

The only other info. I can offer is that the end product is a powdered cheese.

It would seem that the slurry would not be that abrasive but it "chewed" through the original design quickly.

I thought one of the Nitronic grades may work. Yes/No?

Other web sites have mentioned carbide or titanium for possible base materials, but our customer is concerned about metal loss into the product.

I hope this was helpful.

Jeff

 

[TVP]

Perhaps I am not totally understanding the "abrasive" wear environment in your application. You are currently using a 400-series stainless steel heat treated to 55-60 HRC. This leads me to believe it is the alloy commonly known as 440C, as it is the most commonyl used grade with substantial carbon content for high hardness/hardenability. If this type of alloy is not providing adequate wear resistance, then I believe you have a serious problem, that may not be easily solved.

For instance, you mention the Nitronic types of stainless steel. These alloys are very good in certain types of wear applications, but without additional information (of the type I mentioned in my previous email), it is difficult to make a positive recommendation. First, they are not heat-treatable, so the hardness is only going to be in the range of 30 HRC, not 55-60 HRC. If high hardness is a requirement for this application, then I would not recommend the Nitronic stainless steels.

I cannot see how titanium would be suitable for this application, for the same reasons I just mentioned. The strength and wear resistance of titanium and its alloys will be roughly similar to high strength austenitic stainless steels like the Nitronics or 201/301. Cemented carbides (such as tungsten carbide in a cobalt matrix) may very well be better suited to this application, since they will have superior hardness and wear resistance. However, other things like fracture toughness, method of fabrication, etc. need to be considered.

The concern about metal loss into the product seems odd considering that the current application is being "chewed" up, although having bits of carbide floating around in a cheese food product doesn't sound very appealing. Considering the lack of details you have provided, I would investigate one of the following options:

1. Alloy steel instead of 400 series stainless, heat treated to appropriate range (I don't know what this would be), which is subsequently nitrided. The nitrided layer would provide a certain amount of hardness and corrosion protection, which may or may not be adequate for your application. Timken Latrobe is the maker of the standard grade known as Nitralloy. You can obtain more information from their website:

http://www.timken.com/products/specialtysteel/engineering/engineer.asp

2. Apparently I am not as current in my high hardness stainless steels as I should be. While looking at Timken Latrobe's website site, I noticed several grades under the section "knife steels" which they claim to be superior to 440C. You may want to check out Sandvik as well-- they make stainless and alloy steels for high wear applications (knives, saws, cutting tools, etc.). Sandvik's website is

http://www.steel.sandvik.com/.

3. Consider using tool steel instead of stainless steel, and then treat the surface for corrosion protection. Hard chromium plating may be an option, similar to chrome plating of tool steel plastic injection molds. Places to look for more information would be Timken Latrobe, Carpenter (

http://www.cartech.com),

and Crucible (

http://www.crusteel.co.uk/home.html).

There are many other high hardness, high wear resistance coatings to consider like titanium nitride (TiN), titanium carbonitride (TiCN), etc. One place to look for more information on these types of coatings is Balzers Inc.:

http://www.bus.balzers.com/pages/about.html

These are standard combinations of base material (tool steel, carbide, etc.) and coating (TiN, TiCN, etc.) used for cutting tools (Sandvik, Valenite, Iscar, etc.).

Good luck with your project.

 

[butelja]

Thinking along a totally different line of reasoning, would it be possible to rubber coat the impeller assembly? Rubber lining is used often in slurry pumps handling abrasive products.

 

[bruv]

Have you had a look to see if one of the Stellite alloys might be useful??

 

[CdotS]

It seems you have quite a lot of materials to test and see what works or does nto work. Before you go through this trial and error, you should establish the mechanism/s of failure of the current material. There may be a significant role of corroiosn by your new product (slurry/cheese). Contact a professional metallurgist who can do failure analysis and material selection for you.

 

[KnifeKnut]

Take a look at Crucible's Crucible Particle Metalurgy steels. Very high wear resistance in a stainless steel.
CPM90V CPM60V and CPM30V

http://www.crucibleservice.com/datash.cfm

Also Have you looked at the various conventional stainless Cutlery Steels?
Most of these are based on 440C with higher alloy content, although they give up some corrosion resistance.

 

[mmitpwdba]

We ended up using the CPM90V in our prototype, although, corrosion resistance is a concern. Our customer is currently evaluating it in service.

The original material appears to be a 15-5 or custom 450.
Again abrasive wear was the major concern.

Has anyone had any experience with Carpenter's Custom 465?
The 465 has the corrosion resistance and higher hardness.
But I'm not sure if it would out perform the 90V in wear.

Thanks!

 

[JimMetalsCeramics]

Ceramics and cemented WC have been used for this application. They provide long wear life.

 

[arunmrao]

For a lead or tin atomizer the crucible as well as nozzle segment was made in stainless steel grade 309 or 310. If yiur operating temperatures are higher and wear is rate controlling phenomenon,you could try ceramic nozzles or zircon containing nozzles similar to those used in continuous casting machines.

 

[metman]

Hi purity Alumina (Aluminum Oxide = Al2O3) has a hardness of 9 on the Moh's scale and has a compressive strength of 300,000 psi. Although it has limited resistance to impact loading, this does not appear to be a concern in your application.

Jesus is THE life,
Leonard

 

[bogdy]

Y need some information about the technollogy concerning ellaboration of Al-Li alloys,like parameters of metall casting in controlled atmosphere of argon, handling of components like powder or bars of commercially pure alluminium and powder or metallic lithium.Y want to scetch a installation for ellaboration of different kind of these alloys, for didactical use .

 

[oxilume]

Plasma spray your parts with WC, AlO, or SiC. Or make the part of high temperature Polyurethane.

see:

http://www.elastech.com

Todd

http://www.oxilume.com