QUICK FACTS
Renolit-Werke uses PV-WAVE to analyze sheet thickness and consistency
of plastics as they come off of the line to instantly determine
whether they meet the specified tolerances or need adjustments before
proceeding with production. It provides an efficient quality control
tool and has allowed the Company to develop a reasonably priced
manufacturing system that is also user-friendly.
THE PROBLEM
Plastic sheeting is used in a number of ways from coating furniture
to packaging foods, medicines and sanitation products. In Germany
at Renolit-Werke, one of the world’s leading plastic sheeting
manufacturers, the production process starts with a raw plastic
material in the form of a hot pulpy paste. This is drawn through
a "rolling train" called a Calendar. A sheet is then molded
into a desired size and moved on to a take-up device, which guides
the sheet through various embossing and temperature-regulating units.
Finally, when cooled to room temperature, this same sheet is reeled
onto a roll about six feet wide holding about 13,200 feet of plastic
(more than 2.5 miles). During the manufacturing process, a piece
of measuring equipment constantly traverses about the sheet, checking
its thickness uniformity.
"In the past, we were always disappointed that our thickness-measuring
equipment was capable of determining only three average values from
more than 100,000 per roll. In fact, it was a major 
aggravation
that these data were not displayed and could not be used to regulate
our calendars," said Bernd Schnur, head data-processing engineer
for Renolit-Werke. Schnur's manufacturing plant, located in Worms,
Germany is affiliated with the Renolit group of firms employing
more than 4,000 employees worldwide. In addition to various production
centers in Germany, Renolit also manages plants in Norway, Greece,
Spain and Canada.
THE SOLUTION
A provisional new quality-control system was installed on one of
Renolit-Werke’s Calendar machines. The new system revolutionized
the old by using PV-WAVE, a visual data analysis (VDA) solution
developed by Visual Numerics, to visualize thickness distribution
and production data over time (more commonly known as trending).
After testing was completed, data formats and values were exchanged
via a V.24 interface between the Calendar’s control system
and VAX®station.
"Visual data analysis lets us know immediately at what point
our product is beyond the specified tolerance," Schnur said.
"With PV-WAVE, the rolled-out sheet is graphically displayed
as a rectangle, and its thickness is represented by various color
strips."
RETURN ON INVESTMENT
Until recently, all quality testing had been done manually. VDA
allows the machine operator to know immediately, after 3,300 feet,
whether the end product will measure up to quality requirements
or if changes in a sheet’s parameters are needed.
"In earlier times, processed data were lost after fabricating
a roll. Today we store all thickness values, calendar settings and
job data so we can analyze the production process at a later time,"
Schnur explained.
"We also plan to modernize five other Calendars in Worms and
share visual data analysis with the other production plants. VDA
has helped to develop a reasonably priced manufacturing system that
is also user-friendly. This leads to better user acceptance, which
is one of our most important goals," said Schnur.
WORLD CLASS PRODUCTS, SERVICES,
AND SUPPORT
Visual Numerics has provided technical software
solutions for numerical analysis and visualization for over 30 years.
The company's software products help users understand complex data
from a variety of sources and build business-critical applications.
Visual Numerics offers two product lines: the IMSL® Numerical
Libraries for powerful mathematical and statistical analysis and
the PV-WAVE® visual data analysis development environment. Visual
Numerics also offers customized consulting services for applications
that involve mathematical, statistical, or visual data analysis
to meet today’s business analytical needs.
