How Does a Shrink Tunnel Work?

A shrink tunnel utilizes a conveyor and heat to maintain consistent temperatures within the tunnel chamber. Shrink tunnels are most often used for heat shrink packaging items, but can also be used for curing applications as well.

The three primary types of shrink tunnels are recirculating, infrared, and steam tunnels. The difference between each is how they produce heat. The description below is how recirculating shrink tunnels work. It provides images and descriptions of the primary working components.

1. Heater Bank

The heater bank is the main component for heating the shrink tunnel. The heater bank uses standard heating element coils that heat once the heater comes on. The heat produced is centralized around the heater coil. Recirculating the air helps to obtain an even heat distribution throughout the tunnel.

2. Blower Motors

Blower motors are what recirculate the heat from the heater bank. Proper blower motor settings help to ensure the product obtains even heating throughout the tunnel. If the blower motors are blowing too much air onto the product, the shrink film will burn. 

3. Conveyor

The shrink tunnel conveyor transports products from the tunnel entrance to the exit. The ability to adjust the conveyor speed enables users to control the product dwell time within the tunnel. Different products and materials require varied heat exposure. The ability to adjust the tunnel from a slow crawl up to several feet per minute helps to ensure a consistent shrink with any shrink material. 

4. Control Panel

A shrink tunnel control panel should offer two primary controls. Temperature controls and conveyor belt speed controls. With these two controls a shrink tunnel can be fine-tuned to offer the perfect heat exposure for most applications.

There are many other working parts on a shrink tunnel, but these four components help explain how a shrink tunnel works. With the proper settings, products should enter the shrink tunnel and come out the exit finished.