Up: Glassmaking
Sheet of Glass
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which is circular, and useless pieces of polished glass are made.
2. The whole of the glass covering the large table having an area of about
1,000 sq. ft. has to be ground down to the point of minimum thickness.
3. Additional handling causes accidents.
CONTINUOUS PROCESS.
At the same time that the Ford Motor Company devised their process of
continuous rolling from a tank, they introduced a new continuous method of
grinding and polishing, but this idea had already been anticipated and put
into operation at St. Helens. The invention was the conception of one of
our staff, Mr. F. B. Waldron, and in this process the rough glass, instead of
being mounted on circular rotatable tables, is laid on rectangular tables,
which are coupled together so as to give a continuous train which passes
forward under first grinders and then polishers. In the Pilkington process
the tables are slidingly supported on guides and so coupled together as to
give a continuous bed on which the glass can be laid regardless of the joints
between the tables. The continuous bed of tables moves steadily forward at
the rate of about 60 inches a minute. As the table moves forward the glass,
which is 100" wide, is lowered by means of a sucker on to the table and is
bedded down either with plaster or on wet cloth. The whole machine covers
a length of 680 feet.
In connection with the grinding process mention must
be made of the waste product that it creates. When the grinding sand has
done its work it has to be got rid of. It is contaminated by iron, plaster,
glass and emery, and has a degree of fineness which makes it unsuitable for
any purpose. Therefore, it has to be pumped away
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