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Continued from page 45
detected. The fish-eyes that are actually
detrimental, i.e. those which protrude significantly
above the film surface, are far fewer in number
than the measured and displayed fish-eye count.
Because of the difficulty of picking out these
“projecting” fish-eyes from the rest, the total fisheye
count is generally recognised as an index for
the level of fish-eyes. The principal advantages of
these systems are objective, reproducible
inspection of surface quality and the possibility of
reacting immediately to changes in the fish-eye
level.
The systems are integrated in the company's
internal network. With each roll change, the
inspection data for the particular roll are
automatically stored on an internal server by roll
number and production data.
Application Examples
An example of the successful use of fibre-optic
lighting by Orbita is the inspection of black and
white surface protection films for stainless steel
in transmitted light. Each fish-eye causes an
optical dint in the stainless steel. This
phenomenon is intensified by a thermoforming
process. Because of its high opacity, the film is
very difficult to inspect in transmitted light but
double-sided inspection in reflected light is very
costly and technically complex to achieve.
news & views
Staff Update
Evie has grown
considerably since her first
photo début in RheoTalk
(January - April 07 issue).
She turned 6 months on April 15 and is nearly
full grown at just under 17 kg in weight, which is
still a long way from Mal's weight of 43 kgs. Mal
celebrated his 11th birthday on March 19 and is
biennial 07-08
Inspection systems with a camera are used in the
blown film lines. Only a section of the films are
inspected with resolutions up to 100μm. This
statistically monitoring is sufficient to guarantee
fish-eye-free film quality.
The cast film lines for self-adhesive film with
widths of up to 2,600mm are 100% inspected. In
this case, a very high resolution is achieved to
detect even the smallest defect. The 100%
inspection also enables optimum setting of both
the extruder and the die.
In the adhesive coating zone, Orbita also monitors
the complete web. Here a wide variety of defects
in the film are detected as defects of adhesive
application. In this way, the coating process is
optimised and absolute quality control achieved.
Conclusion
The use of online inspection systems for surface
inspection of PE films has proved successful in
practice and permitted faster, more efficient
detection of surface defects in recent years. As a
result, it has been possible to reduce the number
of rejects and complaints. With these systems, it
is possible to meet continually increasing product
quality requirements, while ensuring efficient
production.
finding that keeping up with a young Border
Collie is challenging. Mal has the strength to play
for a long time - but Evie certainly has the turn of
speed when needed.
Being at work for them is part of their daily
routine - as soon as the car keys are picked up
they are at the door and ready to leave - this is
regardless of whether it is time to come to work
or time to leave. A trip in the car anywhere is
always a happy outing for them both.
About the Authors
Dipl-Phys. Gerd Finn, born 1943, is Quality
Control Manager at Orbita-Film GmbH, Weißandt-
Gölzau
Dipl-Oec. Oliver Hissmann, born in 1970, is Sales
Manager at OCS Optical Control Systems, Witten
Poli-Film Group
As a subsidiary of the globally active Poli-Film
Group, Orbita-Film GmbH is a leading German
manufacture of polyethylene films. Films ranging
in thickness from 7 to 500μm are produced in
widths from 50 - 18mm at this manufacturing
facility, which has a built area covering 51,000m 2
and total area of 210,000m 2 . The company's site
at Weißandt-Gölzau is home not only to Orbita-
Film but also to its sister companies Orbita-Cast
and Poli-Coat, which offer a similarly wide range
of products. The films are used in the packaging,
construction, agricultural and horticultural sectors
as well as in industry and the retails trade.
At Orbita-Film, some 50 blown film machines are
installed in total. At Orbita-Cast (stretch film
producer) and Poli-Coat (manufacturer of surface
protection films), the products are extruded using
the cast film method. www.orbita-film.de
A full copy of the paper is available on
request by quoting OCS005
46 www.rheologysolutions.com