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AutoJet®
pre-polymer spray system
eliminates quality problems
and improves production efficiency
Application:
Foam cutting processes invariably result in a certain amount of
trim foam. In order to recycle the material, the trim foam is shredded
into small flakes and is then blown into a blender, where it is
sprayed with a pre-polymer in order to produce rebounded foam. After
this process, the trim foam can be pressed together in slab stock,
which can be cut and used again in applications such as sound insulation,
seating reinforcement and packaging material.
Problem:
The customer was experiencing quality problems in the recycling
process due to excessive overspray and poor spray patterns provided
by competitive spray guns. In addition, lack of proper heating control
resulted in variations in the temperature and viscosity of the pre-polymer.
These viscosity fluctuations further deteriorated the spray pattern
produced by the guns, causing quality problems in the end product.
Large, hardened pieces of unbounded pre-polymer were often found
in the foam, forcing the customer to scrap the product, which can
no longer be recycled.
 Solution
and Benefits: Two AutoJet VAU variable spray guns were used
in place of the competitive guns and immediately improved the quality
of the end product. Although this alone satisfied the customer,
additional benefits were achieved by installing a complete spray
control and monitoring system.
The
system featured the Model 2250 AutoJet Spray Controller, powered
by SprayLogicTM software. The controller monitors and automatically
regulates the temperature of the pre-polymer by means of a remote
controlled heater, ensuring the correct viscosity at the spray guns.
The
Model 2250 controller also monitors the pre-polymer pressure and
flow rate as well as the air flow to the VAU spray guns. The AutoJet
spray controller regulates the pre-polymer flow by regulating the
RPM of an existing pump group. A system integrity algorithm generates
an alarm when the nozzles are worn or clogged and when the air mixing
orifices are clogged. The ability to monitor and adjust the process
is key to the success of the application, because the spray process
is fully enclosed and cannot otherwise be monitored.
When
not spraying, the system automatically goes into continuous circulation
mode, a unique feature of the VAU, in order to keep the pre-polymer
at the proper temperature. The Model 2250 controller logs time and
material usage for each production batch, and also logs minimum
and maximum values for temperature, flow rates and pressures.
The
additional control and monitoring provided by the AutoJet spray
system has resulted in cost savings due to reduced use of expensive
pre-polymer. Further savings were realized through reduced cleaning,
maintenance and downtime. The system -- with a payback time of less
than one year -- has been so successful that future enhancements
to the system are already in the works.
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