Choosing the proper sealer for the job at hand is essential. Choose the wrong one and your packaging operations will grind to a halt.
What you're sealing and how many need to be done per day or per hour will be the determining factors in the sealer you eventually purchase.
The basic types of sealers are single impulse, double impulse and constant heat.
Single impulse units utilize a single piece of Ni-Chrome wire mounted either in the upper or lower jaw of the sealer to produce the desired seal. Single impulse units use either a round wire element or a flat wire element of various widths. Round wire elements are typically used for what is called cut and seal operations such as working with shrink film. Flat wire elements are available in widths from 1/8" to 3/8" with the 1/8" width being the most popular by far.
Double impulse sealers just what they sound like. These units have an element in both the upper and lower jaws of the machine. Double impulse sealers are normally used in the sealing of thick materials, usually up to 20 mil as well as sealing foil bags.
Constant heat sealers, as oppossed to impulse sealers are always on and ready to go. The units use an electrical resistance heater mounted either in or on the sealing bars. The sealing surface of these bars is typically designed to yeild a cross-hatch pattern in the seal but is also available in a horizontal line pattern as well. Temperature on these units is controlled by a thermostat and a thermalcouple is attached to one of the bars to turn power on and off to the heaters as needed to maintain temperature.
Now that you know the types of sealers out there, we can discuss the different designs. These include hand operated, foot operated and automatic models.
Hand operated units sit on top of a table or bench and are operated by lowering a hinged arm down onto the material being sealed with one hand while holding the material with the other hand.
Foot operated impulse sealers work in the exact same way, but are instead freestanding units that are mounted on a pedestal base and vertical tube. These sealers are activated by depressing a foot pedal mounted on the front of the unit. Being foot operated, this leaves both hands free to move the product in and out of the machine to increase production.
Automatic impulse sealers, like the hand operated units, are set on top of a table or workbench, but these units once the timers are set properly will operate automatically without any input from the operator. The timers will control when the jaw closes, how long the element wire is energized and then the cooling or congealing time before the jaw opens back up. This makes for the most consistant seals as it eliminates operator error. Most sealers of this type also have a manual override switch to make the unit cycle between timer settings if needed.
Once you have decided on the style of unit you will need - hand, foot or automatic, and then the amount of sealing power you need - single/double impulse or constant heat, you still have a couple of more things to decide on.
Depending on the impulse sealer you're considering and the material you're packaging, you may need to decide on the seal width you need to make. Typical choices are a thin, round wire seal and then the flat wire seals that come in 2mm, 5mm, and 10mm.
Impulse sealers are built around the size of the element wire to be used. This means that the transformer mounted inside the unit is specifically designed to power a certain element wire. The only interchangability is with the round wire and 2mm flat element wires.
For example, put a 10mm element wire in a unit powered for with a transformer for a 2mm element and virtually nothing will happen. Conversely, put a round wire element in a unit designed for a 10mm element and see just how fast that wire melts away!
Match the seal width to the job at hand. Round wire elements are normally used in shrink wrapping work or where a thin, narrow seal will suffice. 2mm wide seals are considered standard and are used to creat seals on most packaging. A 5mm seal width is used where a stronger seal is required for either package strength or seal integrity such as food product packaging. The extra wide 10mm seal is most commonly used in medical and dental product packaging where seal integrity is of the utmost importance.
The remaining choice, if you've decided to go with a hand operated impulse sealer is whether or not to opt for the unit with the built-in trimmer which will cutt off excess material to within 1/4" of the seal as it is being made. These sealers a sliding handle in the arm with a 2 sided blade attached to remove excess bag material. As the seal is being made, the operator slides the handle along its track and the cut is made.
Armed with this information you should now be able to make an informed decision and choose the correct machine for your application that will perform well and last a long time.
About the author - Steve Madsen is the owner of Pac-n-Seal - http://www.pacnseal.com, a Suffolk, Virginia based packing and shipping supply company that ships throughout the US and Canada. He has written numerous articles to help business owners with their packaging operations and participates on several internet forums answering questions and offering advice.