Reel, paper machine

Until recently the printing processes have tended to be limited, i.e. flexographic, rotary letterpress (four colours), with gravure (occasionally). The labels are produced in accurate register on the backing paper—on reel-fed machines, printing, punching and removal of trim are carried out as a continuous operation (platens are also used.)... 

Paper stock (or furnish) may consist of a mixture of cellulose, filler (for example clay, titanium dioxide, calcium carbonate), rosin, alum and water brought together in predetermined proportions. The percent of fiber and other furnish materials suspended in the total volume and weight of water is commonly known as consistency . Control of furnish consistency in the stock preparation and papermaking area is a prime prerequisite of paper making. The Fourdrinier paper machine was developed for the specific purpose of converting this paper furnish into a finished reel of paper on a continuous basis. 

By tradition and technical feasibihty, coating and supercalendering for surface quality improvement have been off-hne processes. Today both are increasingly integrated into the paper machine. The final activities in paper and board production are shtting of the full width reels into smaller rolls at the winder followed by packaging the rolls for shipment... 

Broke is an important stock source and occurs on a continuous basis as trims from the wire as wet broke and from the winders as dry broke. It can also occasionally occur as reel slab-offs, in the finishing room or during breaks in the paper machine or coating equipment. Usually all broke is fed back to the process in the approach flow system. Broke treatment starts with slushing in different pulpers. These pulpers are installed under the machine and dimensioned according to the... 

The objective of the process on the paper machine is to produce a continuous paper web of the required quality, uniform in machine (MD) and cross machine (CD) directions. The process equipment consists of the approach flow system, the headbox and the wire section, the press section, the dryer section, often a size press, sometimes a coating station, a calender and a pope reeler. After the web has been reeled up this full width mother reel is cut into smaller rolls with widths and diameters according to the customers requirements. The rolls are then wrapped and made ready for shipment... 

In the 1990s demand increased dramatically. For example in LWC production coating has been changed from an off-Hne to an on-line process. This means, that paper grades with critical properties (very high smoothness and high density) have to be wound on the reel at high machine speeds. Furthermore the reel diameter has been increased from e. g. 2.8 m to more than 3.2 m for better efficiency of the paper machine. This required the development of new reel types. 

In reeling one main requirement is a large paper roll diameter, for two main reasons First to reduce paper loss. A certain loss at each reel is unavoidable, so less reels with larger diameters for the same production reduce the overall loss. Secondly, to allow one single winder to cope with the paper machine output This can be reached by reducing the nonproductive time for parent roll change in this noncontinuous process step. Today Jumbo rolls with diameters of up to 4.5 m are produced. 

Coating machines are separate machines in which a previously produced dry base paper is unwound, coated, dried, and then reeled again (Fig. 7.24). In contrast to coating appHcators placed on-hne in a paper machine (Section 6.8), they are usually called off-hne coaters or OMC (off-machine coaters). 

In a paper mill, one offline coater is usually associated with one paper machine. Sometimes, however, one OMC receives paper from different paper machines. In most cases, the off-line coater has the same width as the corresponding paper machine (except for the edge trim). Some coaters with half width are in operation, where the jumbo reels from the paper machine are split, and the two halves are coated separately. 

The objective of reel-slitting is to convert the large parent reels (machine reels, jumbo reels) from the paper machine into suitable size rolls which can be either sent directly to the end-user, e. g. a printer, or receive further mill-internal treatment such as sheeting. 

Some controls in the process are more complex than just PID control loops. One example is the wet end control which ensures uniform process conditions in the approach flow of the paper machine and in the forming section by maintaining constant consistencies, gas content, charge and other parameters. It involves e. g. special software tools (soft sensors) using wet end data instead of direct measurements to predict basis weight during start up of the machine, when the paper has not yet reached the reel or the quality measurements. Such, wet end controls not only reduce the start up time of the process, but also minimize the consumption of chemicals, i. e. only as much retention aid is used as is really needed to reach a required retention level in the forming section. 

In the following chapters some elements of a paper machine automation system are discussed in more detail. The focus is on QCS and information systems, as they are mainly responsible for the abihty of the mill to maximize quality tons on the reel. 

There are three main parts to all paper machines the forming section, the press section, and the dryer section. Other parts, such as coaters, size presses, calenders, and reels vary from machine to machine depending on the grade of paper being made. 

Other parts of the paper machine vary according to the end use of the paper. These include the size press, calender, reel, and supercalender. 

RE-USE OF BROKE AND WASTE PAPER. This is an extensive and complex area which can only be touched on here. (Broke is the term used for paper made on a machine which does not end up in the finished reel edge trims, waste at reel changes etc.). Examples of relevant factors are ... 

Reel-fed. Like reel-fed labels, but with no backing paper. They are both guillotined and folded on the cartoning machine. Claimed to be more secure than all other types of leaflet. 

The other parameter of lightweight paper to be considered is the porosity of the chosen paper. This is because many cartoning machines use a vacuum type of pickup for the leaflet no matter in what form it may be presented to the cartoning machine. Even so-called reel-fed leaflets have to be cut, picked and moved through folding plates up to the insertion point into the carton. For this reason both specification of paper porosity to air and pick tests (to keep down the amount of lint or dust) are sensible. 

The diluted stock may then be pumped by the fan pump through a series of cleaners and into the machine headbox. An inlet distribution header spreads the stock flow evenly over the width of the headbox. The flow is stabilised by the headbox and passes from the headbox through an adjustable orifice plate called the slice. It is discharged onto the moving wire screen (which is usually of plastic construction), dewatered by a series of devices called table rolls, foils and flat boxes leaves the wire as a formed web of paper. It is further dewatered and dried in the succeeding operation before being wound on the reel at the dry end of the machine. 

The reel spool in the secondary arm is way-controUed. It has to compensate for the growth of the roll diameter. The reel dram is force controlled and follows the movement of the nip. When the secondary arm gets an overlay of a sine movement in the machine direction counteracting at FS and DS, the drum follows without changing the nip load and its CD uniformity. This requires a vertical web run before the reel dram, in order not to influence web tension over the width. The result is an oscillated paper roU (Fig. 6.77), realized with only a few small further hardware components. This feature is very useful for hard paper grades with... 

The continuous process of paper production is interrupted at the reel, when the required roll diameter or web length has been reached. Now the paper web has to be cut, a fresh reel spool started and the finished parent roll discharged. So first the empty reel spool has to be accelerated to machine speed. With a standard Pope reel, the empty reel spool will now be lowered, till the nip is closed (Fig. 6.75). The reel is now ready for the turn-up which will be described separately. 

Paper for continuous forms is wood-containing or wood-free and often contains recycled fibers, usually machine-finished reeled paper. 

Upon exit from the machine, the laminate is interleaved with paper to protect the domes, and then re-reeled. Currently, pick-and-place, screen printer, dispenser, and reflow specialists are working in partnership to produce a fully integrated flowline concept for dome processing and other reel-to-reel applications. The reflow machine is huilt on the same base as the pick-and-place machine (Figure 2) for placement of sticky foils onto PCBs. 

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