Pulp and paper processing equipment includes Fourdrinier machines, pulpers, digesters, refiners, chippers, chip processors, and other specialized machinery for processing pulp and forming paper webs. Typically, paper is made of wood pulp; plant, polymer, or inorganic fibers; or non-fibrous materials. Pulp and paper processing equipment also includes machinery for completing secondary operations such as sizing, calendaring, glazing, saturation, coating, folding, corrugating, perforating, slitting, and sheeting. This secondary processing may incorporated into the initial production process, or completed off-machine with specialized pulp and paper processing equipment.
When selecting pulp and paper processing equipment, paper type and application are important parameters to consider. There are three major categories of paper: commercial paper, industrial paper, and paperboard. Commercial papers are produced as a single layer. Subcategories include text and cover stock, graphic arts and fine arts papers, currency stock, newsprint, packaging and barrier papers, and tissue and sanitary papers. Industrial papers are designed to meet strict technical requirements. Subcategories include coated and coating base papers, saturated and saturating base papers, filtration and separation media, absorbent and blotting media, electrical insulation papers and separators, thermal insulation and fireproofing papers, gasketing and sealing materials, and structural and composite papers. Pulp and paper processing equipment for paperboard is also available. There are three subcategories of paperboard: linerboard, corrugating medium, and solid bleached paperboard.
Selecting pulp and paper processing equipment may require an analysis of secondary capabilities. Sizing is the process of lightly coating one or both surfaces of a paper with a starch solution to enhance surface properties. Calendering presses paper and paper products between two rolls under high pressure. As paper density and surface smoothness increase, porosity and thickness decrease. Glazing produces similar results, but uses a moving ball to apply high pressure to only one side of the paper. Saturation is an immersion process in which paper is fully wetted - typically with a latex dispersion - and subsequently dried. Coating applies one or more layers of material to one or both surfaces of a paper. Perforated papers and paperboard products have minor cut marks in the cross-roll direction. Sheeting cuts a roll of paper into sheets of uniform dimension. Pulp and paper processing equipment that can perform other secondary operations is also available.