This presentation covers Poisson's ratio as an example of a hidden variable that plagues machine operations in the tanning industry. The presentation looks at the way in which the CRC solves production and drying issues to produce higher quality leathers.

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CRC
Innovation in drying and condition
for
ALCA 2017

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Background
• In ALCA 2015 the use of DMTA to monitor stiffness change shown
• In IULTCS 2015 the factors affecting drying in the CRC was shown
• In Munich 2017 the possibility of hidden variables was considered
• In this talk the focus will be on specific results and properties of current
CRC research

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Why CRC?
• Cell rotary conditioning is not a toggling method
• CRC is a consolidation of drying and conditioning that
saves the tanner time

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Advantage?
• Allows focus on leather tension:
• User Poisson’s ratio to its advantage.
• Asymmetric tension on hide during drying.
• Frame design uses load-based opening NOT fixed extension-based.
• Computer and robots adjust tension during drying to ensure optional set.
• Allows focus on control of leather moisture:
• Ensuring precision level of moisture.
• Cellular nature of machine eliminates weather conditions.
• Allows focus on leather type (cellular drying of leathers).
• Allows focus on minimizing human error.
• Allows production adaptability and competitiveness.

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Poisson’s ratio

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Leather tension control 1
• Tension drying achieves area gains (profit).
• As the asymmetric frames are split across the width the
tension causes tension across the backbone.

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Leather tension control 2
• Hides are not uniform width - a fixed tension on drying will result
in differing % set.
• The neck and the butt differ in width and do not like being
stretched to the same extent.
• Astringency of tannage and retannage cause differing rates of
drying and shrinkage (and tension) during drying.
• Previous research shows fat-liquor to change the drying rate
• Astringency of chemistry can cause major shrinkage changes

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Leather tension control 3
• Hides are not uniform width - a fixed tension on drying will result
in differing % set.
• The neck and the butt differ in width and do not like being
stretched to the same extent.
• Astringency of tannage and retannage cause differing rates of
drying and shrinkage (and tension) during drying.
• Previous research shows fat-liquor to change the drying rate
• Astringency of chemistry can cause major shrinkage changes

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• Operators do not always tightly toggle the neck - so the
frame will open more
• Sometime the structure of the leather allows more opening
in the butt (or vice versa)
• CRC automatically takes the leathers individual Poisson’s
ratio into account

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Leather tension control 4
• Hides are not uniform width - a fixed tension on drying will result
in differing % set.
• The neck and the butt differ in width and do not like being
stretched to the same extent.
• Astringency of tannage and retannage cause differing rates of
drying and shrinkage (and tension) during drying.
• Previous research shows fatliquor to change the drying rate
• Astringency of chemistry can cause major shrinkage changes

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CRCLab

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Leather moisture control
• Hidden variables,such as the effects of weather are not well
understood.
• First phase drying usually occurs from outside in.
• CRC achieves drying from inside out (sets butt area first).
• Tension optimization is achieved.
• Leather is conditioned in holding buffers.
• Cells have highly specific conditions for leathers to optimized area gain
and moisture level.

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Leather type
• The thickness of the leather pre-determines the drying conditions and
those conditions have to be set on the machine (on room)
• In CRC the cell conditions can be independent of the cells before and
after.
• Many outstanding chemistries have been achieved,they have been failed
by the drying method.
• The CRC lab is used to determine drying conditions for a specific leather.
• The incoming (recycled) air is controlled by computer to focus on changing
drying patterns.

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Drying

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Human error
• Drying operators tire during the day of toggling.
• Operators also place toggles according to what they think is necessary
for the leather.
• Placement of toggles is critical for area gain.
• CRC will compensate for poor placement and poor tension.
• Operators will need work breaks (especially during lunch).
• The CRC will condition after computer/robot controlled program is
complete,obfuscating human control over drying.

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Independent cells design

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Production advantage
• Research into chromium leather (and in particular chromium-free leathers) benefit
from no sammy-setting prior to drying.
• % set is customizable so area yield is increased.
• Recycled air systems,computer and robot control of drying means lower energy
costs.
• Carbon footprint is lower
• Elimination of over-drying and focus on customizable quality parameters during
drying results in higher cutting yield.
• Logistical production scheduling is possible as individual leather drying times
programmable.

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Conclusion
The CRC is a tool for the tanner to achieve increased:
• Area yield due to load-based split frames.
• Increased cutting area because of customizable quality control.
• Fewer drying machines and time.
• Lower energy cost and carbon footprint because of machine design.
• Less dependence on human inputs,because of machine
compensation.
• Easier production logistics because of cellular construction.

21. Adriano Peruzzi | adriano@istitaly.com
Karl Flowers | karl@authenticae.co.uk
Thanks
for the attention