Dear yborice,
After a thorough search, I have located the proposed Israeli national
standards for residual stress in glass containers. These standards
ought to be representative of manufacturing norms in other highly
industrialized countries. I did not find any other national standards
published online. However, see further below for an ISO document that
you may find useful.
I should mention that the proposed Israeli standard cites the American
stress measurement standard ASTM C148-00, "Standard Test Methods for
Polariscopic Examination of Glass Containers".
These test methods describe the determination of relative
optical retardation associated with the state of anneal of
glass containers.
ANSI webstore: Standard Test Methods for Polariscopic Examination of
Glass Containers - ASTM C148-00
http://webstore.ansi.org/ansidocstore/product.asp?sku=ASTM+C148-00
As you may know, the temper of glass is a measure of the residual stress
after annealing, which is also referred to in the literature as residual
strain, thermal stress, and other such variations.
Temper -- The degree of residual stress in annealed glass as
measured using polarized light techniques.
SKS Bottle: Glass Glossary: Temper [page 8 of PDF document]
http://www.sks-bottle.com/Glass_Glossary.pdf
The proposed Israeli national standard uses the ASTM measuring methods
to derive a number called T_R, the Real Temper, and specifies that it
must not be higher than 4. The document includes, in section 2.4.2, a
table showing the relationship between the Apparent Temper, T_A, and the
analyzer rotation measurement obtained from polarimetric examination. In
section 2.4.1., T_R is obtained from T_A by the equation
T_R = T_A * 4.06 / T
in which T is the thickness in millimeters of the container's side wall
at its base. Note that in the idiosyncratic English of the Israeli
document, residual strain is termed "remaining effort". I have made
several amendments to clarify the text.
2.4 Remaining internal effort (temper number ^2)
[Herein] are examined the internal pressures that remain
in the container after the temper process, using one
of the two methods described in the document of the
American Society for Tests and Materials ASTM C 148,
with the changes detailed hereunder:
2.4.1 Polariscopic examination
For T_A values up to [and including] 3[,] T_A = T_R
For T_A values higher than 3 are calculated the
T_R values according to the formula:
T_R = (T_A * 4.06) / T
[Where]:
[T] -- Thickness of the side wall measured
[at] the base of the container (mm)
T_R -- Real Temper [Number] ^2
T_A -- Apparent Temper [Number] ^2
The T_R values [shall] not be higher than 4.
============================================
{^2 Temper Number: Number that expresses the remaining effort
in the tempered glass}
2.4.2 Polarimetric examination
In the polarimetric examination are obtained
values defined in the aforementioned document as
analyzer rotation. These values are [translated]
to T_A values as detailed in table 6 and [are
used to calculate] the T_R -- Real Temper as
detailed in paragraph 2.4.1 .
The T_R values [shall] not be higher than 4.
============================================
Table 6 -- Transition from analyzer rotation to
apparent temper
Analyzer rotation Apparent temper [number] (T_A)
----------------- ------------------------------
From 0.0 up to 7.2 1
From 7.3 up to 14.5 2
From 14.6 up to 21.7 3
From 21.8 up to 29.0 4
From 29.1 up to 36.2 5
From 36.3 up to 43.4 6
From 43.5 up to 50.7 7
From 50.8 up to 57.9 8
From 58.0 up to 65.1 9
From 65.2 up to 72.4 10
European Commission: Enterprise and Industry: Glass containers for food
and beverages; Amendment No. 1; Israeli standard IS 172 [Word document]
http://europa.eu.int/comm/enterprise/tbt/tbt_repository/ISR114_EN_1_1.DOC
I have furthermore located the ISO standard that I believe is most
pertinent to your situation. This standard is issued by TC 63, the
Technical Committee for Glass Containers, and is numbered ISO 9058:1992,
with the title "Glass containers -- Tolerances". I do not know whether the
prescribed manufacturing tolerances include a maximum residual stress,
but I bring this document to your attention in the hope that you will
have some use for it. If not, I trust the Israeli national standard will
suffice as a guideline.
International Organization for Standardization: ISO 9058:1992, Glass
containers -- Tolerances
http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=16627&scopelist=
International Organization for Standardization: Technical Committee TC
63, Glass containers
http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?COMMID=2106
It has been an interesting challenge to answer your question. If you have
any concerns about the accuracy or completeness of my research, please
advise me through a Clarification Request and allow me the opportunity
to fully meet your needs before you rate this answer.
Regards,
leapinglizard
Search strategy:
glass container maximum stress
://www.google.com/search?hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=glass+container+maximum+stress&btnG=Search
container annealing standard
://www.google.com/search?q=container+annealing+standard&hl=en&hs=wYy&lr=&client=firefox-a&rls=org.mozilla:en-US:official&start=10&sa=N
glass residual strain maximum standard
://www.google.com/search?q=glass+residual+strain+maximum+standard&hl=en&hs=5FJ&lr=&client=firefox-a&rls=org.mozilla:en-US:official&start=10&sa=N
glass bottle residual strain stress maximum standard
://www.google.com/search?q=glass+bottle+residual+strain+stress+maximum+standard&start=0&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.mozilla:en-US:official
glass container mechanical performance standard
://www.google.com/search?hs=Lhy&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=glass+container+mechanical+performance+standard&btnG=Search |
