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pulpstock flow as it exits the headbox chamber. In 1829, John Dickinson invented a reversing press. The suction box, used to squeeze water from the web, was first developed in France. In 1836, John Brown received a British patent for a suction press. Appearing much later, in the 1870s, were machine showers and fourdrinier wire guides, to hold the wires in place.

Improvements at the finishing or dry end of the machine did not generally evolve as quickly as at the wet end. This is somewhat ironic because in early paper Mills most finishing tasks were considered less skilled and consequently left to women. However, machine calenders and supercalenders were in use by the 1830s, although requiring individuals to tend and individually feed sheets. Slitters and cutters appeared before mid-century. In 1847, J. C. Kneeland, of Troy, New York, patented a mechanical layboy, which stacked the sheets as they Fell from the cutter. In a subsequent patent dispute, Kneeland prevailed against three other applicants.

Many of the famous names in U.S. papermaking machinery date from the pre-Civil War period. Rice Barton Corporation, Worcester, whose predecessor was formed in 1837, and the Bird Machine Co., South Walpole, are two examples from the large Massachusetts paper machinery industry. Two of the principal manufacturers of today were organized in 1858, the Merrill Machine Company, now known as the Beloit Corporation, and the Bakers Falls Iron Machine Works, now known as the Sandy Hill Corporation.

Wood fibers were first used for papermaking in a Marysville, Pennsylvania mill before the Civil War in 1855. Groundwood, or mechanical spruce wood pulp, was first introduced into Canada in 1866 and to a U.S. mill the following year. Machine felting appeared during the Civil War. The use of sulfite, an acid reagent, originated in 1867 with the American chemist, Benjamin Tilghman. The sulfate or kraft process was first developed by the German chemist, Carl Dahl in 1889. Kraft pulping, using spruce and pine, became the most common pulping method in the United States. Initially spruce and poplar predominated among U.S. pulpwood species, accounting for 88 percent of consumption in 1899. As pulpwood production shifted to the South and West, other hardwood and softwood species, notably southern yellow pine, gained predominance.

The Voelter-Keller stone grinder, first manufactured by J. M. Voith of Germany in 1847, was patented in the United States in 1858. In 1858 Joseph Jordan and Thomas Eustace of Hartford, Connecticut produced the first Jordan refiner, which consisted of a conical plug rotating in a matched conical shell. Named for its Co-inventor, Joseph Jordan, the Jordan was long the standard means of pulpstock refining. In 1856, J. Klingsland offered a disk refiner manufactured by Cyrus Currier & Sons, Newark, New Jersey. However, the four revolving disks could not be machined finely enough by then current machine tools, and disk refining did not supersede jordans

until the 20th century. In 1862, the first Harper fourdrinier was introduced, a variant used for production of lightweight paper grades. The first patent for rubber roll coverings was issued in l864.

The post Civil War period offered several of the industry's major producers the opportunity to expand and take recognizable shape. In 1893, the Beloit Iron Works manufactured a paper machine for display at the Chicago World's Fair. This machine exposed many people to papermaking machinery for the first time. The machine was subsequently sold to a mill and remained in service until quite recently. In the same year, the Black Clawson Company started business.

The industry would carry on into the 20th century, developing new

technologies and serving the country through two wars. Throughout the century, American paper machinery would reach into Mills around the world from Canada to China. As a new globally competitive industry emerged after 1960, American-made paper industries machinery was recognized globally for quality, long life, and service. New challenges were to emerge to press this U.S. leadership. 1

Paper Industries Machinery: What Is It?

Paper industries machinery (SIC –-standard industrial classification--3554) encompasses the principal products manufactured to serve the needs of the pulp, paper, paperboard, and paper converting industries. Products of this industry serve the Paper and Allied Products Major Group (SIC 26) from woodyard to converting and finishing. The major focus of this assessment is on manufacturers in the paper machinery industry as defined in the SIC nomenclature. Equipment such as boilers, Black liquor recovery systems, pumps, and pollution control devices largely lie outside the purview of this study. Woodyard equipment (barkers, chippers, knotters, etc.) prepares the raw pulpwood into roundwood or chips, for processing into pulp. Pulpstock May then be processed into market pulp or various grades

* There is no complete history of paper machinery in the United States. This section is drawn from several Works including: Clapperton, Robert H., The Paper-Making Machine, (Oxford, 1967); Hunter, Dard, Papermaking, Dover, New York, NY, 1978 (reprint of 1943 ed.) ; Juckett, J. Walter, In Retrospect, privately published, 1985; and McGaw, Judith, Most Wonderful Machine, Princeton, NJ, 1987, esp. pp. 95-116, 158-186. Also see "Origins of Groundwood Pulping," J. N. McGovern and C. H. Carpenter, Tappi Journal, January 1988, pp. 201-202.

of paper. A recent survey showed rapid expansion of Mills designed to process modern mechanical pulps. 2

There are currently some 257 Mills worldwide (97 in North America) employing various mechanical or chemical pulping processes, including thermomechanical pulping (TMP), for market pulp, newsprint, and other grades; and chemi-thermomechanical pulping (CTMP), largely used to produce newsprint; and chemi-thermomechanical pulping pressurized groundwood pulping (PGW). Traditional kraft pulping, used for production quality publication grades, corrugated boxes, bags, and sacks, remains the most common method used.

Mechanical pulping yields about 90 percent pulp from the entire tree, and as a result it is a more economical pulping technology. It can be used mostly for processes such as newsprint and other papers where rapid yellowing of the sheet is not a problem. Chemical pulps, on the other hand, yield only about 50 percent pulp from the same wood.

Most mechanical pulps are used in conjunction with chemical pulps to produce paper. Exceptions are newsprint, which can be produced from 100 percent TMP and so-called free-sheets used for writing and fine papers, which are manufactured from 100 percent chemical pulps.

In manufacturing stone groundwood pulp, raw pulpstock goes through a grinder. Chemical pulp is first cooked in a digester, which May be of a batch or continuous design. Pulp refiners are central to the TMP-CTMP processes. A disk refiner consists of one or more pairs of ribbed disks. The other disk is stationary or rotated in the opposite direction. Pressure applied to the suspended paper stock acts to "roughen" the fiber surface as it passes between the disks for better bonding into a sheet. The refined pulp is washed to remove impurities and then bleached to raise brightness. Market pulp will be partially dried or dewatered before shipment. Wet lap machines fold the pulp before shipment.

The Fourdrinier Machine

The fourdrinier machine produces most grades of paper and paperboard. The machine consists of four sections: the wet end, the press section, the drier sections, and the calender and reelup. A brief description of each segment follows.

The primary wet end part, the headbox, is a flow control chamber which receives the paper stock or pulp furnish from the stock

2 Pulp and Paper, January 1986, pp. 73-76. In the future, this assessment will use the term paper machinery industry for the industry encompassed by SIC 3554.

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This chart is not designed to represent the steps involved in the production of any single grade of paper. It is designed to identify the major steps in the process which are described in the accompanying text.

preparation system and, using baffles, delivers an even, uniform flow of the paper stock onto the fourdrinier wire. A slice at the end of the headbox regulates the flow onto the fourdrinier wire. This wire is a continuous plastic or metal-woven wire belt which runs over a series of rolls, hydrofoils, and suction boxes which pull out the water. The paper web forms and partially dewaters on the fourdrinier wire and then transfers (at a point known as the couch) to the press section for further dewatering. Felts pick up and carry the wet web through the press sections to the driers. From the drier, and if desired, the paper can enter the calender section (a series of stacked rolls which smooth the paper and impart the desired gloss or thickness to the sheet) and is then reeled up. Coated paper grades May receive additional treatment on a supercalender. The paper is then wound into a roll on a rewinder. The finished roll May go to a finishing room for cutting (cut size paper) or making into smaller rolls. 3

In recent years, the twin-wire has emerged as a major modification to the standard fourdrinier table. In a twin-wire the forming distance is much shorter. The pulp slurry emerges from the headbox in a vertical upward flow. Two separate wires come together at a forming nip point as the slurry enters the nip. The web is then formed and partially drained, continuing along one of the two wires until it is picked up by a felt and transferred first to the press section and then to the dryer section. Machine speed is higher in a twin-wire, allowing greater production and better sheet formation. A highly competitive situation has arisen for twin-wire orders to rebuild existing fourdrinier tables into twin-wire machines. The leading U.S.-based producers, Beloit and Black Clawson, have each evolved several twin-wire models. Among foreign producers, Valmet (Finland) and Voith (West Germany) offer the greatest competition to U.S.-based builders.

Finishing and Converting Equipment

The industry also encompasses producers of equipment for paper or paperboard finishing and converting. This group includes machinery and equipment for bag-making, corrugated and folding box-making, and drum, can, and tube-making. Except in the corrugated box segment of the industry, firms engaged in manufacturing equipment for finishing processes such as specialized coating are generally smaller in size than firms producing basic pulp-making or papermaking machinery. The bulk of the remaining industry products consist of parts and attachments.

3 For a lay description of the industry, see Pulp and Paper Primer, TAPPI Press, Atlanta, 1983.

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