I received a call from a customer in the textile industry. The customer was producing a fabric that ends up being used for furniture. The fabric varied in width between 4 feet (1.2 meters) and 6 feet (1.8 meters) wide. In one of the processes, the material went through an oven to be heated to 200 deg. F (93 deg. C). This would “set” a fire retarding chemical compound in the fabric. As the fabric web exited the oven, they needed to cool it to roughly 120 deg. F (49 deg. C) so it could be handled by the operators.
The customer tried their luck at designing a duct that was seven feet (2.1 meter) long by one foot wide (30.5 cm) by one foot tall (30.5 cm). At the bottom of the duct, they cut one inch wide (2.5 cm) slots along the length in an attempt to create a wide airflow across their material. The large metal box (ducting) was suspended across the fabric and oriented to blow air straight down onto the material. On the open end of the metal box, they mounted a fan to blow air inside with the intention that the slits in the duct work would direct the air from the fan onto the fabric.
Their idea worked to some small degree, but the cooling results were simply too little to continue with this kind of solution. Fortunately, the customer knew about EXAIR Corporation and they contacted us to see if we could help. Because they needed to provide additional time for the fabric to cool, they slowed their line speeds down to 20 yards/min (18 meters/min). It was obvious that they wanted to increase the throughput if they could.
In order to increase throughput, we needed to figure a way to increase the cooling rate. To increase the cooling rate, we can either use colder air or more air. Given the wide format of the material, the best decision for this application would be to blow more air across the target material. The Super Air Knife has a 40:1 amplification ratio. For every 1 part of compressed air, it will entrain and move 40 parts of ambient air to the target surface. The result is that a larger volume of air hitting the surface of the material. More volume hitting the target means we can cool it quicker. I suggested a model 110272, 72″ Super Air Knife Kit to span across the different width of fabrics. It can be mounted across the width of the material and set at a 45 degree angle to the material in a counter flow orientation. The reason for the angle and the counter-flow orientation are to enhance the cooling effect provided by the Super Air Knife. Orienting the Super Air Knife at a low angle allows for the flow coming from it to stay in contact with the material web for a much longer period of time.
By removing the fan with the duct work and installing the Super Air Knife, they found they could increase throughput to 30 yards / min. (9.2 meters / min). A 50% increase. The customer was thrilled about the significant increase as this was a real bottleneck in their production process.
If you have any cooling issues, you can rely on EXAIR to determine the best product. If you have any questions or would like to discuss any of your applications, you can contact the Application Engineers at EXAIR.
John Ball, Application Engineer