Heat-shrink tunnels can effectively process labels, sleeves or bands that conform to container shapes, offering companies packaging benefits ranging from tamper-evidence to 360-degree coverage, from brilliant graphics to efficient product flow. By automating what could prove a time-consuming process of hand-shrinking bands via use of hot-air guns, these devices offer tremendous labor savings not to mention consistent product appearance.
But not all heat tunnels are the same. Various types offer differing benefits, and realizing the strengths of each type—convective heat, radiant heat and steam heat—will enable companies to pair their needs to the right machine.
Many factors should be considered, including: film type used, container material, product inside the container, environmental concerns, and product temperature at the time of sleeve application.
Weighing the options
Understanding the specifics of each type of heat-shrink tunnel can prove helpful in making correct decisions about which will partner well with a given application.
Convective tunnels utilize forced hot air to provide the heat energy required to complete the shrink process. The tunnel usually includes a fan of some type to force air through a heat source, resulting in a heated air stream. Many tunnels feature a recirculation system to pull the heated air back into the process, resulting in a more efficient tunnel. In some cases, industrial hot-air guns are used as the heat source and fan.
Infrared tunnels utilize radiant heat to provide the energy required to complete the shrink process. These tunnels utilize various energy sources from quartz panels, tubes and, in some cases, standard calrod-style heating elements with reflectors.
Steam tunnels use live steam to provide the energy required to complete the shrink process. Most, if not all, steam tunnels require that a separate steam source be used to provide the steam to the tunnel...