A sealer is a machine that seals containers filled with packaging materials. After the product is filled into the packaging container, the container must be sealed in order to preserve the product in a hermetically sealed manner, to maintain product quality and to avoid loss of the product. This operation is done on a sealing machine. The machine used to seal the container after packaging. There are many materials used to make packaging containers, such as paper, plastic, glass, ceramics, metal, composite materials, etc., and the shape and physical properties of packaging containers vary.

Flexible containers are bag-type containers made of paper, plastic film, composite film and other flexible materials. The sealing of such containers is mostly composed of an integrated machine with bag making and filling, and is seldom used separately. Due to different materials, the sealing device is also different. Mainly used for plastic cups, plastic boxes, plastic bottles filling, and the corresponding composite film sealing products production. Such as frozen, juice, milk, yogurt, drinks, fast food and other materials filling and sealing.

Can be used as filling materials for liquids and slurries of different viscosities, and also for packaging of containers of different shapes and capacities. Heat sealing bags are widely used in the fields of daily chemical products packaging, food and drug packaging. As the leakage is most likely to occur at the heat seal of the bag when the product is filled, and most of the damage to the bag in actual use also occurs at the heat seal part, choosing the right heat sealing material and heat sealing parameters can reduce the scrap rate of the production line and effectively improve the overall barrier performance of the package. Heat sealing is to heat the sealing material in a certain way, so that it reaches the state of viscous flow, and then pressurize it to make it stick. It is generally accomplished by hot press sealing device or hot press sealing machine.

Based on the heat sealing structure and heating method, the heat sealing method can be categorized into ordinary heat sealing method, melt sealing method, pulse sealing method, ultrasonic sealing method, high frequency heat sealing method and induction heat sealing method. Ultrasonic sealing and high-frequency heat sealing are more suitable for films that are easily deformed. The most commonly used heat sealing method is ordinary heat pressing. Commonly used heat pressing sealing methods include flat plate heat sealing, disk heat sealing, belt heat sealing and slip clip sealing. Flat plate heat seal is the most popular.