A minority of glass tougheners operate what might be described as a continual flow
system, from glass break out, arrissing and toughening, which to the inexperienced
observer, may sound like a good system, because it reduces the volume of work in
progress. There are however, several problems with this system.
Glass cutting, arising and toughening, all work at different speeds according to
the sizes of glass being processed, so linking them all together, means working at
the speed of the slowest link in the chain. At the start of the optimised run, usually
a higher proportion of bigger pieces of glass will be coming off the cutting table.
These are quick to break out per square metre and are a lot quicker to aris. Towards
the end of the optimised run however, as average glass sizes get smaller, both break
out and arising take a lot longer per square metre of glass, so the toughening plant
ends up with only partial loads, which degrades quality and increases toughening
The sequence that glass emerges from break out, may have a mixture of very large
and very small sizes, which if loaded in that sequence on a toughening bed, will
produce numerous quality, or even safety problems.
A more recent and worrying trend is for certain equipment manufacturers to provide
the ability physically to link glass cutting, arising and toughening so that the
three processes can be carried out without human intervention. In our experience,
it is only relatively inexperienced glass companies who are turned on by this concept.
Older and wiser glass people see a multitude of problems with this marriage of technologies:
if one item of equipment is down, the whole manufacturing process is down; when
cutting and edge deleting Low E glass, the whole manufacturing process runs at approximately
half speed; when remaking the last few broken or rejected pieces of glass, the waste
in glass cutting can be catastrophic and the whole line is blocked from pressing
on with the next batch of work; as turnover grows, it is perhaps only one of these
processes that needs another capital purchase, which if physically linked, requires
extra capital purchases of both the other processes in addition to their requirements
for shop floor space. In short the wiser people will say “Too many eggs in one basket”,
or “I want the ability to mix and match my production resources in any ratios, without
any limitations, making it easier to catch up after any piece of equipment goes down”.
The only “advantage” of any automatically linked flow production system, is the attempted
elimination of glass handling. Inexperienced people tend to put too much emphasis
on this “advantage”, whereas glass handling with the correct slot racks, as used
in Trimloss, holds little fear for wiser souls. (See - Supporting Acts - Slot Racks).