Plastic bag – you can use them for groceries, shopping or taking out the trash. Chances are there’s a growing pile of them somewhere in your kitchen. With so many everyday uses, it’s easy to see how people can get carried away with plastic bags
The plastic bags we use every day are made from granules of linear Polyethylene resin that will be melted. They combined the linear polyethylene with another low-density one in the mixture. However, manufacturers changed to use Calcium carbonate masterbatch to decrease cost of resin but its quality is still stable. In case, they want to produce colorful plastic bags, producers can mix more black masterbatch, white/gray/brown/yellow masterbatch… as “colorant” as well. These materials are known as new fillers helping them improve price as well as quality products finally. The granules are perfectly blended into a homogenous materials.
After granules melt and the extruder which heats them to a temperature varying between 356 and 465 degrees. This machine produces a film of Polyethylene in a form of a tube. It is several hundred feet long has a minimum of thickness of two ten thousands of an inch and a circumference of twenty inches. The plastic tube gradually pulls down. The rollers then flatten out the plastic tube.
The polyethylene film is now easy to work. And now they cut the tube on two sides to obtain different rolls. The knife then cut the film to required width. The excess strip is salvaged in this too. Several hundred feet of film are produced and rolled up. This particular roll contains the required quantity of film when the roll is full, the film is cut. This roll moves forward and can be transported to another department . An empty roll begins to filled up automatically. A full roll weighs 348 pounds and can produce 35.000 bags.
The next step is printing on the bag. The alcohol-based ink circulates continuously to retain its viscosity. Impressions are made by inking rollers. They can apply another color on the banks. When printing is over, the plastic film is rolled up again, the roll is now fall and the cutting of bags can get started. They also arrange a machine to make sealer bonds the edges of the bag together with heat. The wheel picks up the bag and puts them on to spindles that can hold 250 each. Here they are making banks with the hermetic zipper
The zipper is made from a plastic pad that inserts into a slot. The zipper is made in advance and is unrolled progressively. The zipper strip is cut and heat bonded to the back at 356 degrees. In the other department of plant, they make plastic bags with handles printed bags circulate on these rollers. Te machine that welds the sides gives the bags the desired shape. Then, another machine with a punch cut the handle holes. Bags are heat sealed and cut at 302 degrees
In some other pattern of plastic bags, people can seal just one end of the bag and the machine make hole(s) so that it can let air out of the bag when it is being filled to allow them to be generously filled with items. At this stage, a stamper cut the handle holes. That makes people easy to take it out. Bags are cut to the required size and automatically sealing the other side of it. A plant can makes eight types of bag for an overall total of over one million a day.
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