Breakthroughs in PVC Welding and Cleaning Systems
the past few years the demand for vinyl windows has continued to remain high and
as a result the competition between the large (500 or more units per shift) PVC
window manufacturers has intensified. Significant pricing pressures have been
placed on each manufacturer by the major distributors they supply. As a result,
manufacturers have been looking for ways to decrease their production costs
simply to maintain their ever-decreasing profit margins.
production area of keen interest during the past two or three years has been the
production rates for welding and cleaning of the PVC window frames and sash.
to the intrinsic nature of the welding process, a specific time (30 to 40
seconds) is required to weld a frame or sash. Since the process time is fixed,
the only way to increase production rates is to have multiples of the welding
machines (requiring large capital expenditures, manpower and floor space) or to
develop ways to weld multiple frames or sashes simultaneously in one machine.
efforts to weld multiple frames during one weld cycle started many years ago.
However, it is only in the past year or so that we have been able to weld as
many as four main frames in one cycle successfully or six sash in
one cycle while holding the required size tolerances of
order to succeed, technical challenges involving fixturing designs, heater plate
configurations and welder structural design had to be overcome. As a result of
having met these technical challenges and having now increased welding
production rates by factors of two and three, the production
bottleneck became the next step in the manufacturing process, which is the
corner cleaning task.
order to keep up with the welder output it first became necessary to develop
twin-head cleaners which would clean two corners at a time. (The
original corner cleaning machines worked on only one corner at a time and it
could take well over a minute to complete just one frame or sash.) As the welder
volumes have increased even further in the past year, it has become necessary to
evaluate and develop four-head cleaners. These four-head cleaners
(all four corners cleaned simultaneously) have proven to be most successful in
sash applications where both corner cleaning and secondary sash processing (e.g.
tilt latch routing, weep slots, pivot bar holes, etc.) are required after
the same time that individual welding and cleaning machine capacities were
increasing, we were developing more automated welding and cleaning systems.
These would decrease manpower requirements, eliminate handling and increase the
quality of the product while taking advantage of the increased volumes made
possible in the advanced welding and cleaning machine designs.
of the unique welding and cleaning systems presently in operation is the Sigma
7000 System developed specifically for multi-level (up to three)
main frame welding/cleaning. This system includes a horizontal four-point welder
with automatic ejection of the welded frames on to a transfer system that
automatically loads the frames into a matching four-head NC corner cleaner. The
cleaner then ejects the completed frame that would be passed on to the next
manufacturing or assembly phase.
Sigma 7000 has the ability to produce one frame every 30 to 45 seconds and
requires just one operator.
latest development (presently in the design phase) is the Ultra 6000 welding and
cleaning system which is designed specifically for sash. It will
eliminate the welder ejection system and the intermediate buffer stations
required on the Sigma 7000 and replace them with an overhead “pick and
place” system. This will decrease significantly the time required to remove
the completed sash from the welder and decrease floor space by about 50 percent.
“pick and place” system will grab all four sash (or as many as have been
welded) simultaneously and remove them from the welder in one motion. The sash
will then be transferred over to the cleaner where the “picker” will act as
a magazine loader and place one sash at a time into this four-head cleaner. The
cleaner will eject the completed sash so it can be glazed. Once all four sash
have been “dropped” by the “picker,” it will return to the welder to
gather four more sash.
Ultra 6000 is expected to produce one sash every 20 to 30 seconds (including
secondary processing operations), and it will require one operator.
much effort has been spent on multi-level welding and multi-corner cleaning,
very little time has been spent evaluating the time it takes for the operator to
load parts into the welder.
the loading time (for as many as 24 parts when welding six sash per cycle)
becomes the largest single time factor in the overall process (i.e. load, weld,
present, the challenge is to develop a reliable system for magazine loading
multiple parts in less time than is required with manual loading … stay tuned
for further developments.
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