Extrusion is the procedure used to create polyethylene film and bags. The production of plastic film begins with the melting and softening of tiny plastic pellets (called resin).
The bubble is made by forcing molten plastic through a circular die to create a long, continuous tube. After the bubble has been blown up to the necessary diameter, it is hauled vertically up a tower to cool before being flattened to its lie flat width. The rate at which the film is withdrawn from the die determines its final thickness. The quantity of air in the bubble determines how wide the film will be. In this way, the key to successful film production is high-quality machinery that guarantees a steady supply of raw materials. During the melting process, a different color film may be made by introducing resin pellets containing the desired pigment.
Flexographic printing, which involves platemaking, mounting, and printing, is the next procedure.
The first of the three platemaking techniques is plate creation using light-sensitive polymer. This is usually used by most of poly mailer manufacturers. The second approach involves a computer-guided laser etching the picture onto the printing plate. The third strategy calls for shaping the plate.
When a photograph is mounted, it is secured to a rigid surface so that the image is as clear as possible. An individual plate is created for each color that will be printed, and this plate is then mounted on a cylinder and fed into the printing machine. Flexographic plates include mounting markings to aid in proper alignment on the cylinder. The printing process cannot properly coordinate the various colors without these markers. When it comes to putting these plates on the printing cylinders, precision and specialized gear are essential.
The last step in flexographic printing, printing, results in a finished product that is both functional and aesthetically pleasing, the package. The procedure calls for making a 3D relief of the desired image out of rubber or polymer, which acts as the positive mirrored master. When inking a printing plate, ink is transported from the ink roll to the anilox roll, where surplus ink is eliminated, leaving only the raised image portions on the rubber or polymer plate. The last step in the process involves pressing the polyethylene film between the plate and the imprint cylinder to transfer the image.
A plethora of “inline” processes follow flexographic printing. Bags of varied lengths on rolls may be made using a bag manufacturing machine to seal and perforate the film. Bags may be detached and trimmed to size because of the film’s severability. Small bags may be produced at rates of up to 53,000 bags per hour because of the high cycle speeds of the machines. If the bag is very big, the output per hour may be as low as 2,000. Vent holes, punched through the film in a selection of patterns and sizes, may also be added.
Extrusion is the procedure used to create polyethylene film and bags. Flexographic printing, which involves platemaking, mounting, and printing, is the next procedure. The key to successful film production is high-quality machinery that guarantees a steady supply of raw materials. Flexographic printing involves making a 3D relief of the desired image out of rubber or polymer. Bags of varied lengths on rolls may be made using a bag manufacturing machine to seal and perforate the film.