The Science of Web Handling
Imagine investigating a crime
committed by invisible perpetrators. Even witnesses would be unable to
identify the culprits. Your case would have to be based on what could be
seen at the crime scene and on circumstantial evidence. Troubleshooting
web handling problems is like that. The most important web handling
variables are stress and strain, and even with today's technology, there
are no practical methods for observing them in a production environment.
The only evidence of them, with the exception of gross averages, such as
MD stress, is in consequences such as wrinkles or misregistration. Good
web handling troubleshooters have to learn to look at a web and visualize
the invisible details of stress and strain to diagnose the problems.
So, how does one learn the art of seeing the invisible?
Like anything else that has invisible
causes, it's easy to make up plausible, but completely wrong, theories
(myths) about how stress and strain produce problems. For example, before
1960 lots of web processors were completely confused about how misaligned
rollers caused webs to shift laterally (and often wrinkle). One of the
favorite myths was that "the web tracks to the tight side". In
the middle of the twentieth century this and other mysteries began to get
sorted out by small groups of researchers working in many different
For decades much of the best work
stayed in desk drawers at the companies where the work was done. But, in
the 1980s some enlightened engineers (friends of mine - Dr. John Shelton,
and Bruce Feiertag) recognized the need to coax this knowledge out into
the open, where it could be organized and extended to create a recognized
branch of process technology. This was something whose time had come,
because by 1986, working with Dr. Karl Reid at Oklahoma State University,
they had found enough like-minded people at major corporations to meet the
corporate sponsorship requirements for a federal program to create the Web
Handling Research Center (WHRC) at OSU. Beginning in 1991, the Center
began sponsoring bi-annual IWEB conferences where serious researchers
meet, present papers and discuss their latest work. The university has
also graduated a number of students who earned their PhDs with web
handling research projects conducted in the center's well-equipped lab.
The WHRC has been an outstanding success. In its nine volumes of conference proceedings you will find most of what we presently know about how to "see the invisible" correctly. In fact, long-term participation in the WHRC's work (plus deep familiarity with the contents of those nine volumes of proceedings) has become the de facto credential for web handling expertise - a qualification possessed by all of the leading web handling consultants.
The success of the WHRC is
demonstrated by the fact that, the Association
of Metallizers, Coaters and Laminators (AIMCAL) has begun offering
application-oriented conferences and training programs based on its work.
Four of the leading web handling consultants are now actively involved in