|PAPER MAKING PROCESS|
|Paper Mills contain a number of processes with different purposes. These processes vary widely, depending on the paper mill and the type of paper product that is produced. Most paper mills can be divided into three groups of process.
1. Stock Preparation, to get the stock ready for paper machine to be made into paper
2. Paper Machine, Paper machine processes are divided into two areas
3. Finishing Operations, take the sheet from the reel and prepare it to be shipped to customers.
a. Wet end operations, remove water from the stock and form a sheet.
b. Dry end operations, to dry the sheet, coat it and smooth it, and wind it onto large reel
Stock preparation is the interface between the pulp mill or pulp warehouse and the paper machine.
The primary concern is to produce a uniform papermaking furnish to ensure stable paper machine operation and high standard of paper quality. It treats and modifies each furnished constituent as required, and then combine all the ingredients continuously and uniformly into paper making stock.
In the stock preparation process, baled pulp (or other fibrous raw material) is dispersed into water to form a slush or slurry. The extent of repulping can be just sufficient to enable the slurry to be pumped, or it can be adequate to totally separate and disperse all the fibers
Now it's time to make paper out of our pulp. That mainly means getting the water out of the wood-fiber soup, since this papermaking stock is about 99% water. The first area in which this takes place is called the wet end of the papermaking machine
First, papermakers spray the stock onto a long, wide screen, called a wire. Immediately, water begins to drain out the bottom of the wire. This water is collected so that it can be reused over and over again. Meanwhile, the pulp fibers are caught on the top side of the wire, and begin to bond together in a very thin mat. The fiber mat remaining on the wire is then squeezed between felt-covered press rollers to absorb more of the water.
Even when this wet end work is over, the pulpy stuff on the wire is still about 60% water. But now it's time for the dry end.
In the dry end, huge metal cylinders are heated by filling them with steam. The wet paper, which can be up to 30 feet wide, passes through these hot rollers - sometimes dozens of them, and often in three to five groups. Heating and drying the wet sheet seals the fibers closer and closer together, turning them gradually from pulp into paper.
When you look at a piece of paper, can you find any difference in thickness in that single sheet? Probably not, thanks to a part of the paper machine called the calender - big, heavy cast iron rollers that press the drying paper smooth and uniform in thickness.
Sometimes the paper is coated, often with fine clay, to make it glossier and easier to print on
A bit more drying, and then rolled onto a big spool or reel, the pulp - a miraculous mat of fibers from trees - has become paper and further converting process following it through cutters and sheeters transfer the paper to various size of rolls and sheets ready for a thousand uses.
After going through final finishing processes (sorting, wrapping, counting, cartoning, palletizing, labeling, etc.) and meets customer requirements, final products are ready for delivery.