Vitrified CBN and Vitrified Diamond

[RamingtonStall]

Vitrified CBN and Vitrified Diamond Grinding wheels appear to be increasingly successful in O.D. and I.D. Cylindrical Grinding applications of Cutting Tools, Bearings, Automotive parts, Appliance Parts, etc.

What has been your experience with Vitrified CBN Grinding Wheels? Vitrified Diamond Grinding Wheels?

When it worked, what worked? Why?

When It failed, What Failed? Why do you think it failed?

Have you used Vitrified SuperAbrasive Wheels for other applications? Double Disk? Face Grinding? Creep Feed? etc.

 

[RamingtonStall]

As no responses to date, Try again:

Does anybody here know the difference between "Hot Pressed" Vitrified CBN and "Structured Porosity" Vitrified CBN?
Description? Applications? Where to use? Costs? Other differences? Methods of Using? Limitations of each?

Same Questions for Vitrified Diamond?

RamS
SAT SuperAbrasive Techniques, Inc.

http://www.IndustrialDiamondCBN.com

 

[HectorMontalvo]

Hi, in my short experience with grinding CBN wheels in centerless machines i can tell you this:

-It has longer life that common wheels.
-You can increase the dressing part in the double for blind materials.
-The dressing works much better and faster than in normal wheel, and for shapping into the wheel (using a rolling diamond dresser).
-The most of the times, this fail (i mean crash or explote) because of human mistakes, like excess in the pressing (more than 25 - 30 psi), don't use guards, etc.

 

[RamingtonStall]

HectorMontalvo (Industrial),

Were you using Resin Bond CBN Centerless Grinding Wheels or Vitrified CBN grinding wheels?

The early problems which I encountered with Resin Bond CBN Centerless grinding were in Dressing the wheel. We used various Dressing Sticks, Dressing Bars which could be thru-fed ground to dress the wheels, Grease with Aluminum Oxide in it to coat the wheel and then grinding a bar, etc. The key was always to avoid Glazing the Wheel. i.e. True gently and then Dress followed by more trueing and dressing, etc. until the wheel was ready to grind.

With the Open Structure Vitrified Bond CBN wheels, I have found that the Dressing operation can be eliminated.

RamS




SAT SuperAbrasive Techniques, Inc.

http://www.IndustrialDiamondCBN.com

 

[ceramax]

I have developed a new material that could be used for dressing the diamond wheel, better than Norton norbide stick. If you want a sample to evaluate, email to me at c_max_tech@yahoo.com.

 

[genagur]

Our company has developed and tested a technology for inducing variable and controllable pores into vitrified CBN wheels. We will have editorial article on our new technology in the Industrial Diamond Review magazine. Test results and technical papers are available. Write to me at gurinovich@abrazive.spb.ru

 

[Biffi]

People,
I have some experience in vitrified cbn grinding of niquel base alloys for automotive components. Usually this tool must work with mineral oil, (water based collant wear to fast the cbn grits - some studies in Brazil). Its is good to be applied in Ni alloys, and have advantage in steel grinding when compare with diamond. Some reseachs say that in high temperature, some carbon eletrons of the diamond migrate to steel structure which forms Fe carbides. It makes the grit fragile and wear too fast. The key point of vitrified CBN wheels is the dressing operation. The dressing ratio and speed have a great influence in the part roughness
Compare with conventional abrasives the CBN life time is 10-20 times bigger, and the production rate 3x high.
Also I have experience with CBN metal bond cut off disks and single layer CBN wheels.
If somebody needs more info let me known.
biffi

 

[RamingtonStall]

Biffi,
I would like to offer several comments concerning the wear of the crystals:
===============================================
1) Ref your comment: <<&quot;Some reseachs say that in high temperature, some carbon electrons of the diamond migrate to steel structure which forms Fe carbides. It makes the grit fragile and wear too fast.&quot;>>

RAMS COMMENT:
The chemical reaction of diamond when grinding steel does involve the migration of the carbon from the diamond crystal to the steel in the presence of the heat from grinding as you suggest. The Diamond Crystal then becomes progressively more and more polished or flat which increases the heat effects and leads to a death spiral for the diamond crystal.

====================================================
2) Ref your comment: <<&quot;The key point of vitrified CBN wheels is the dressing operation. The dressing ratio and speed have a great influence in the part roughness.
Compare with conventional abrasives the CBN life time is 10-20 times bigger, and the production rate 3x high.&quot;>>

RAMS COMMENT:

Yes. I agree with many Vitrified Bond systems this is true. Approximately 18 years ago, we did tests with the Noritake CBN Sharpener on 80/100 mesh CBN Vitrified Bond 200 concentration wheels and found that we could vary the surface finish from 40 micro-inch to 4 micro-inch simply by changing the depth of feed and traverse rate of the sharpener. The effectiveness of the sharpener made the obvious choice be 80/100 mesh CBN.

The Key point for Engineered Porosity Vitrified Superabrasive wheels is to minimize or even to eliminate the need for dressing the wheels. We typically use 170/200 mesh CBN5 and rarely go above 140 concentration to achieve the desired finishes without needing to micro-true the CBN crystal by the Trueing/Sharpening operation.

We are currently offering a Technology Package for making these types of Structured Porosity wheels with up to 50% AIR. Please contact me at RamS@Free-Market.net if you are interested in further discussions or would like to debate the point.

In the meantime, enjoy your beautiful weather in Brazil! We are now COLD up here in Ohio!

==================================================

Best regards,

RamingtonStall



SAT SuperAbrasive Techniques, Inc.

http://www.IndustrialDiamondCBN.com