Page 47 - Glass Machinery Plants & Accessories no. 3-2019

A NNEALING ous ‘plastic’ stages

LEHR CYCLE
and characterised
Glass is described as a
cosities.
These
mineral product obtained by a by different vis-
melting process that cools down define the charac-
without crystallisation and finally teristic points of
takes a solid state. This definition glass annealing,
provides the basis of the anneal- such as working,
ing process. softening, anneal-
Every glass type (soda lime, ing and strain
borosilicate, etc.) is characterised points and annealing
by a different batch composi- range (the tempera-
tion and consequently, a differ- tures between soften-
ent temperature-dependent vis- ing, annealing and strain
cosity and expansion coefficient. points). Through knowledge
During melting, the batch passes of the annealing range, tempera-
continuously from a solid to a liq- ture limits for each stage have
uid state. At forming it is brought been established.
back to a solid, passing the vari- With innovative glass machin-

glass machinery plants & accessories 3/2019
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