Corrugated box plant controls cut accuracy and

Industry:
Packaging
Application:
Cut Control
Corrugated box plant controls
cut accuracy and reduces scrap,
and realizes hugh monthly savings
Profile:
US manufacturer of corrugated
box products
Solution:
LaserSpeed® 4000
Results:
 Dramatic increase in accuracy
of board length
 $16,875 per month savings from
reduced scrap on product changeovers
or any time the line is down
 Decrease in maintenance
Corrugated box production
The manufacture of corrugated boxes is a complex process.
Corrugated box material or board is made by taking rolls of liner
or paperboard, called a web, and drawing them through gear-like
cylinders which shape the web into precise waves. Glue is applied to
the tips of the waves and pressed against a liner. Another liner may
be applied to the other side. The resulting board can be made with
different strengths depending on the thickness of the web source
materials.
Now that the corrugated board is made, it is further converted into
precise lengths which will then make up the final product. The
discrete lengths are made by a cutter. The knives of the cutter are
controlled by a cut signal. A variance in the signal will cause a variance in the cut. Corrugated box manufacturing lines run in different
configurations that depend on the age of the equipment, type, cost
of the material being made, and type of drive systems that are used
on the line and the knife.
The Challenges:
A US corrugated box manufacturer wanted to better control
the cutting process and reduce material waste at one of its
production plants. The precise control of the knives is
important as it determines the accuracy of the discrete
boards. The biggest issue or waste, however, happens when
the line goes down for any reason. For example, if the line
goes down during a product changeover.
When the line goes down, the line performs what is called a
“tail-out”. A tail-out occurs when the main board is sheered
anywhere from 50 feet to 100 feet before the knife (varies
from plant to plant). The board at this point is being pulled
through the knives by the pull roll that is part of the knife
system. The board is accelerating at this point by up to 2 to
3 times the main board line speed. This part of the board run
The Solution:
The corrugated box manufacturer implemented
Beta LaserMike’s LaserSpeed non-contact measurement
solution which consists of two (2) LS4000 encoders to measure
the actual board speed as it enters the knives. The LS4000
units project a unique pattern on the surface of the board.
As the board moves, light is scattered back to the units.
This information is translated into product speed. The speed
signals from the LS4000 units provide the control system with
precise pulse counts to control the cutting knives.
Critical Process Factors. The box plant had several process
considerations to take into account in order to select the
appropriate length and speed measurement solution. First,
the measurement system had to be extremely accurate in
order to better track and control the actual velocity of the
main board line speed versus the speed of the pull rolls during
normal production and tail-out situations. This would help to
avoid measurement errors due to slippage issues. Second, the
system needed to accurately measure and monitor the board
length as product progressed down the line to the knife
Control Cutting Process and Reduce Waste
is referred to as the tail. Hence the term tail-out was coined.
The problem with the tail-out lies in the fact that the speed
of the board tail varies because of slippage and “out-ofcalibration” pull rolls. The configuration of each of the knife
systems varies, but usually they have both a top and bottom
knife which requires two pull rolls controlling the speed.
Because of the tail-out problem, the box plant was scrapping
the entire tail. Figure how long the tail is and how many times
the line goes down a day, as well as the cost of the material,
and you can easily come up with the amount of loss due to
this problem.
LaserSpeed® 4000
system to ensure the desired product length was being
achieved repeatedly. Last, the plant required the measurement system to be more reliable than its current contact
mechanical encoders and pull roll drive encoders to minimize
downtime and maintenance issues due to mechanical failures,
recalibration, and service-related tasks.
Installation. The LS4000 units are mounted just before and
as close to the actual knife system as possible to minimize the
distance between the measurement system and knife. The
benefit of using the LS4000 units at this point is that the cuts
can be controlled very accurately during normal run or
tail-out mode. This accuracy helps eliminate scrap and
increases product quality. The scrap, or waste savings, that
the LS4000 units can achieve is determined by the distance
between the main board sheer and the knife system, and also
the amount of product changeovers per day and the percentage of scrap on each. Some plants throw away the whole
section of board from the tail-out.
The Results:
The corrugated box manufacturer realized several benefits
by implementing the LaserSpeed solution on its corrugated
board lines.
 Dramatic increase in accuracy of board length
 Huge savings from reduced scrap on product
changeovers or any time the line is down
Decrease in maintenance
A somewhat hidden cost in traditional contact measurement
systems, such as wheel tachometers, is due to maintenance.
Contact systems wear and have to be re-calibrated. The
LaserSpeed solution is non-contact and has no moving parts to
wear. LaserSpeed is also permanently calibrated which further
reduces maintenance.
Savings per day = Number of product changeovers x Distance
main sheer to knife x Percentage scrap x Cost of product
At the corrugated line, the distance from the main board
sheer to the board knife is 90 ft. The box plant had 100% scrap
at each tail-out. The plant performed an average of 25
changeovers a day. The average cost per foot was $0.25.
Savings per day = 25 x 90 x 1 x 0.25 = $562.50. That is $16,875
per month or $202,500 per year.
Calculating the savings from scrapped tail boards
 Number of product changeovers = XX per day
 Distance from main sheer to knife = XXX ft or m
 Percentage of scrap each tail-out = XX %
 Cost of product (average or actual) = XX $/ft or $/m
Beta LaserMike’s LaserSpeed non-contact encoder is the most accurate, reliable,
and cost-effective measurement solution for cut control and reducing waste.
To learn more, visit: www.laserspeedgauge.com
Beta LaserMike USA
8001 Technology Blvd.
Dayton, OH 45424 USA
Ph: +1 937 233 9935
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