PMEL Forum

Because our steel gage blocks are starting to show excessive wear (17 years old), we are considering replacing them with ceramic blocks. They seem to be a good replacement and are about $3000 cheaper for a set. Does anyone have experience with ceramic blocks? Please let me know your opinion about the pros and cons of them.

Thank you for your input!

Don't drop them they chip easily.

We have both, and I'm not an expert in that area.  But I think one of the advantages of the ceramics is the a little bit better temperature coefficients.  I think the material is a little harder, so abrasive wear and tear may be a little bit better, along with maybe less sensitivity to corrosion from skin oils.  But, of course, there is the chipping problem as mentioned.

Are you sure the ceramics aren't $3000 more?  A typical 81 piece Grade 0 Ceramic Set runs around $4800.00 while the same grade in steel is around $1600.00

Ceramics will last a lot longer and be more stable if taken care of.

I was refering to Chromium Carbide blocks, not steel. Sorry.

ceramic blocks are awesome and much easier to ring, easier to care for... but you will be sad if you drop them.  you can dent the steel ones too so you can't base a decision on mishandling. 

Quote from: bAdbOb on 04-10-2015 -- 07:41:29
I was refering to Chromium Carbide blocks, not steel. Sorry.

That makes sense.  I prefer the croblox myself.  I have a few sets that have lasted decades with only a few blocks having to be replaced.  You don't want to drop them either but they seem to have less downside than ceramics as far as chipping.

If your blocks are only used in a standards lab and are well cared for, all being equal, the ceramics at a cheaper price probably has more appeal.

back in the day the Air Force used to support the ceramic gage blocks. I believe the reason they stopped was due to the different coefficient of expansion rates of ceramic, steel, chrome-carbide. Even though they are pretty close, you always had to do the math. If, for example, you have steel blocks and the item you are calibrating is also steel, then there's no problem since they both expand at the same rate. Another thing to consider is that steel acclimates faster to changes in temperature; chrome-carbide being the worst. If you take these blocks outside a 68 deg room, be prepared to explain the longer "soak times" for chrome-carbide. They are awesome to have, just need to know the particulars about them.
To answer your question, see this link for comparisons between the blocks.
http://starrett-webber.com/GB63.html

One other question:
What is you opinion of square gage blocks vs Johansson blocks?

Thank you for your help!!!

Quote from: bAdbOb on 04-14-2015 -- 08:45:45
One other question:
What is you opinion of square gage blocks vs Johansson blocks?

Thank you for your help!!!

A Swedish machinist named Carl Johansson invented gage blocks in the 1890's.  I think you are asking about the comparison of rectangular blocks to square?

Square blocks are handy because they come with a hole in the center for tying the blocks together (especially useful for larger blocks) while rectangular blocks are easier to handle and are easier to layout.  I prefer rectangular for small blocks and square for larger blocks for this reason.