WELDING COUPLED AND POLYPROPYLENE BAGS
When it is necessary to weld bags of food in coupled or polypropylene, it is possible to orientate on welding machines with double welding bar specifically designed to weld this type of material.
Thanks to the double sealing bar, bags in coupled material and with bellows are easy to weld as the heat is diffused on both sides of the product.
These machines differ in the dimensions of the sealing bars, the type of welding (impulse or hot bar) and the fact that they can be placed on a bench or supported by an upright.
Type of bars: impulse or hot bar?
Impulse welders are characterized by the fact that the bars are generally cold and heat only when the impulse is given by the machine.
Thanks to these characteristics it is possible to realize very precise welding even with the mechanical or lever pedal models as the welding is managed by microns and timers.
These models make smooth welds with a width of 5 or 10 mm.
Hot-bar welders weld with two constantly hot bars; they are equipped with resistance, temperature controller.
Unlike impulse welders, the result of a hot-bar welding performed on a manual model depends very much on the skill of the operator as they are devoid of timers and he will decide the welding times; these welders can make knurled welding from 12 to 14 mm.
The impulse and hot bar welders are available in the following models:
- Clamp sealers: very practical and light welders that allow you to weld even large bags without having to move them.
- Lever-operated bench: practical, easy-to-move welders with reduced dimensions allow to weld envelopes with high thickness, in coupled and with bellows thanks to the double 10 mm sealing bar. The operator must then hold the bag with one hand and activate the lever with the other; the operation can be uncomfortable and impractical if you need to weld many bags during the day.
- With mechanical pedal: more professional welding machines than the previous model, they are available in the version with reinforced upstand (max load capacity of 20 kg). The welding with mechanical pedal drive could be less precise because the pressure is decided by the operator and not electronically.Despite the presence of the upstand with support surface this type of welding machine is not recommended if you need to make a large number of welding during the day because the mechanical pedal requires more effort on the part of the operator compared to models with electric pedal.
- With electric pedal: the electric pedal welders can be either benched or vertical with reinforced upstand. The presence of the support surface allows the operator to have both hands free to position and support the bag during welding. The electric pedal ensures uniform results and allows many welding to be carried out effortlessly by the operator.
Marking of the bags
The previous welders do not have a marker for lot and expiry so if you need to add this information, you must take into account the purchase of a separate marker or evaluate the purchase of a continuous welding machine.
The continuous welding machines are faster than the welding machines listed above because they are equipped with a driving belt for the transport of the bags. The welding takes place during the dragging and, at the end of it, a marker is placed which carries out the marking.