Tanning is a notoriously
time-consuming and often wasteful process. The fresh hides received
by tanneries are of an extremely irregular shape and in order to
facilitate their processing, the leather manufacturer needs to trim
the hides at several stages during the tanning process. At each
trimming, scraps are discarded that have been treated to some extent
along with the rest of the hide, and as the trimming is carried
out further along in the processing cycle, scraps represent greater
and greater losses in terms of processing energy and materials.
Tanning efficiency would be substantially increased if all the trimming
could be done early on.
This project was aimed at demonstrating the
technical and economical feasibility of the early geometrisation
of calf and bovine hides, and at developing an industrial-scale
prototype machine for the automatic cutting.
Partners initially focused on the basic question of whether or not
it was even possible to carry out all of the trimming before processing.
Using specialised software, optimum algorithms for early geometrisation
were elaborated. From there, a prototype cutting machine had to
be built and trials carried out. All of these steps were completed
successfully and together demonstrated that animal hides could indeed
be trimmed completely with minimal error before any processing took
The focus then turned to the question of economic feasibility and
whether the process was sensible in terms of costs and benefits.
The answer was a resounding yes.
Economic and environmental performance
First, indirect gains were demonstrated through
the possibility of recycling the raw leather trimmings, which could
now be produced in larger and more complete sections. Prior to this
project, the treatment and disposal of scraps represented seven
to ten percent of leather manufacturing costs. Savings were demonstrated
in terms of reduced consumption of processing materials, as smaller
amounts of water, energy and chemicals are needed to produce the
same amount of leather. Processing chemicals currently represent
15 to 18 percent of leather manufacturing costs. The discharge of
toxic chemicals like chromium is thus also decreased. This entails
a cost reduction for tanneries, which pay upwards of 80 euro per
ton of discharged chromium-contaminated material.
Finally, efficiency was increased in terms of reduced time lost
during multiple trimming operations. Overall cost savings have been
estimated at 0.006-0.009 euro per square metre.
The project results have provided an enormous boost for the ongoing
development of automated processes in the leather tanning industry.
The new algorithms for early geometrisation provide the means for
obtaining the regularly shaped hides which are a prerequisite for
the automation of mechanical operations. In addition, working conditions
are greatly improved with the elimination of dangerous operations
like old-fashioned manual cutting with knives.
Partners have now suggested that even further savings could be realised
in disposal and transportation costs if the trimming of hides were
carried out at the slaughterhouse level.
French project partner Digital Control,
long known for its advanced waterjet cutting machines, is now successfully
marketing the Trimjet 150, a commercial version of the trimming
machine developed during this project. It comprises a leather conveyor
unit, visualisation and image processing unit, waterjet cutting
unit, high-pressure pump and control and supervision unit, with
an optional return belt allowing loading and unloading by a single
operator. The system is computer controlled with a suite of efficient
and user friendly applications providing contours, hole and defect
detection, image processing and leather hide area identification.
Simulation of the trimming operation and yield estimation can also
be performed. The applications are compatible with Window 95, Windows
98 and Windows NT operating systems.
As for the European leather industry, with an annual turnover of
nearly 10 billion euro, over 3,000 companies and some 50,000 people
directly employed in the sector, it has long demonstrated its competitiveness
on the global market. With ongoing modernisation initiatives such
as that shown in this Brite-Euram project, combined with investment
in training, environmental infrastructure and export promotion,
the industry looks set to face the future with continued confidence.