×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Visible defect size in ceramic

Visible defect size in ceramic

Visible defect size in ceramic

(OP)
I'm not sure if this is the correct forum but none of the others seem to be right, so here goes:

We buy in a ceramic cutting blade. The inspection criterion for the edge that we have agreed with the manufacturer is that there should be no visible defects along the cutting edge when viewed at 15X magnification. OK, so this is somewhat subjective but it works satisfactorily and we have no complaints.

For entirely different reasons we would now like to quantify the size of any defects that are not visible at 15X magnification.

Question: What would be the largest defect (i.e. a notch)that could be present but remain invisible at 15X mag. Assuming 20/20 vision and a quality 15X microscope.
Grain size of the ceramic is 0.5 micron diameter.

RE: Visible defect size in ceramic

The human eye has a resolution of approximately 0.2 mm to 0.5 mm.  At a magnification M = 15, the resolvable object size would be 13 µm to 33 µm.

Regards,

Cory

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Visible defect size in ceramic

We use a similar system for tungsten carbide.  What a person can “see” also depends on training.    A person can “see” things that are too small to actually see by picking up on a discontinuity in light on an edge for example.  

We typically use 30x as a standard and specify by three dimensions.  

The simplest way is to insert a reference object in a digital photo or use a calibrated set up.   

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com

RE: Visible defect size in ceramic

I posted a simple version of what we use.   

http://cs4u.org/Basicsawtiporderingwithquality.pdf

In all honesty I have been in too many meetings where everyone had their own micrometer (or other instrument) and everyone was trying to figure out if the parts were in spec or not.   I think that trying to go with a crack you can see could cause problems.  

In addition I think the materials you are working with are most likely sintered and incidental edge roughness caused before sintering is entirely different than edge roughness cased after sintering.  

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com

RE: Visible defect size in ceramic

Very impressive, Tom.  

There is a minor typo in the 3rd item in the Chips and Cracks.  External is misspelled as "extrenal."

TTFN

FAQ731-376: Eng-Tips.com Forum Policies


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources