Ultrasonic welders

Bonnie Bates <bbates<-a t->ngc< . >chin< . >gc< . >ca> writes:

>We are currently researching the various types of ultrasonic welders on
>the market. What advice could you give us; pros, cons, and personal
>experiences would be most appreciated.

At the University of Michigan we have used for many years two
polyester welders that are not ultrasonic: the Monarch Economy and
the Crossweld, both made by Preservation Equipment, Ltd. Both
machines use a heating element to melt the polyester film together;
the Monarch at the edge of the film and the Crossweld on a line
across the interior of the film.

The "pro" for these machines is their comparative low cost. They do
weld polyester film for encapsulating documents. Beyond that,
however, I would call them temperamental at best. It requires a
light and skilled touch to weld consistently without overheating or
burning the polyester (our Monarch burns if you casually leave a
finger on the lever during a weld.) If a burn does occur, all work
must stop while you disassemble the machine and meticulously scrub
away all traces of melted plastic with fine steel wool, replace the
heating element, or both. To continue work without first cleaning
the machine only compounds the problem. The weld line produced by
the Crossweld is thicker and clumsier than that produced by the
Minter welder. With both machines it is difficult to squeeze out the
excess air from the encapsulation; documents are liable to slip
around inside the encapsulation and the pillow effect is markedly
noticeable in a stack of encapsulated documents. Both require
welding in stages for documents larger than about 20 inches,
although I believe larger machines of the Monarch style have now
become available. The Monarch edge welder I have found most useful
for producing polyester sleeves with a weld on one edge only.

Just this past summer we were at long last and gratefully able to
purchase a Minter welder, thanks to some help from a generous
private donor. I wish we had been able to go that route first.

Shannon Zachary
University of Michigan Library
837 Greene St.
Ann Arbor, MI 48104-1048
734-763-6980
Fax: 734-763-7886

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                  Conservation DistList Instance 11:53
                 Distributed: Friday, December 12, 1997
                       Message Id: cdl-11-53-003
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