Thickness Tolerance Standard Validity

[jasonduo]

I had several thickness issues with a recent import from a Chinese supplier. Asked them about the problem and they sent a picture (attached below) and said it is "international standard". Is what they claim true or is it something fabricated to avoid responsibility?

Context: We purchased a large CTcP plate order last month which contained three different sizes in question: 560x670 (0.25mm & 0.30mm) and 600x730 (0.30mm). Their thickness before processing does not have any issues, however, 600x730 plates (0.30mm) after processing are only ~0.26mm (+-0.005mm), which supplier claimed to be ~0.265mm, while 560x670 (0.25mm) dropped to ~0.22mm.

We had a history of thickness issue with another supplier, and while this situation is not as severe as the previous, it is still damaging since our customers' machines cannot hold them in place (their machines are old and some cannot be adjusted). The bigger picture in this situation is that the plates is not usable after processing, while Huaguang plates received no complaints of thickness by anyone.

 

[Alois Senefelder]

Hello jasonduo,

The Plates you received ARE within ISO Standard, the most used thickness is 0.30 (0.12 thou).

Question: WHY are the plates not usable after being processed ???????????????????????

Most modern Offset Presses accommodate 0.30mm Plates as standard!

I also suggest for your enlightenment! you find out how Anodized Aluminium Plates are manufactured.

Regards, Alois

 

[jasonduo]

Hello jasonduo,

The Plates you received ARE within ISO Standard, the most used thickness is 0.30 (0.12 thou).

Question: WHY are the plates not usable after being processed ???????????????????????

Most modern Offset Presses accommodate 0.30mm Plates as standard!

I also suggest for your enlightenment! you find out how Anodized Aluminium Plates are manufactured.

Regards, Alois

Hi Alois,

Thank you so much for responding to my question regarding the thickness standard.

I may have used wrong wordings which caused confusion raised in your question, so I would like to clarify that the plates are usable after processing, however when delivered to the customers, some responded that their machines cannot hold the plates in place for printing due to being thinner than what the machines are capable to hold. This would not happen to Huaguang's CTcP plates 100% despite sharing the same thickness and still retain most of the thickness after processing.

Any opinions on this strange phenomena?

Jason

 

[SteveSuffRIT]

ISO Standards are often the least common denominator, to meet the needs of the many/most.
ISO often uses language of "shall" and "should". Should is tighter than shall.
What specific ISO standard are they referring to?
I can't think of anything (exposure. processing, handling) that would change the caliper thickness of an aluminum metal plate!
A 0.30mm plate is about 0.012".
Their low end tolerance limit is 0.042mm which is 0.00165", or rounded up, 0.002".
In theory, that might not sound like a lot, but in practice, it may be significant.
Would you reset squeeze or impression pressure for this difference in blankets, packing, or paper?
Do you have a micrometer sensitive enough to detect this slight difference?
I wonder how many times printers have told customers that the color variation is within acceptable industry standards (SWOP, SNAP, GRACoL, G7, Fogra, ISO, FIRST)?

 

[Alois Senefelder]

Hello Jason,

Ask your customers - WHY are they unable to reset the Press Plate Clamps for the various Calipers of Plates ????

OR - don't they know how?

Regards, Alois

 

[gordo]

I can't think of anything (exposure. processing, handling) that would change the caliper thickness of an aluminum metal plate!

Temperature.

 

[SteveSuffRIT]

Yes, temperature does affect dimension (size) of metal.
However, the thermal expansion for aluminum is only 24 um/m/1'C.
0.001" (1 mil) = 0.0254um
So while the width (40") and length might change ever so slightly, the caliper thickness would be unmeasurable to 5 decimal places.
No mechanical micrometer would notice this, you would need an optical device (laser).