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The mineral substance coating on a sanding belt that removes material from the board.
Material introduced into a panel during the manufacturing process which imparts a particular property. Additives include preservatives, water repellents, and fire retardant, but not binders.
A substance (glue) capable of bonding material together via surface attachment – such as a laminate to a panel.
The American National Standards Institute standard which sets forth requirements and test methods for dimensional tolerances, physical and mechanical properties and formaldehyde emissions for medium density fiberboard (MDF). Methods of identifying products conforming to the standard are specified. Property requirements are described in metric and imperial units. A summary of this standard is available in the Composite Panel Association’s “Buyers & Specifiers Guide” which may be viewed on-line at (www.pbmdf.com). The complete standard is available from the Composite Panel Association, or from ANSI at (www.ansi.org).
Test methods published by the American Society for Testing Materials (www.astm.org) which may be used by MDF mills for quality control purposes.
A non-decorative laminate used on the back of composite panels to protect them from changes in humidity. Backers are often used to balance laminated panel construction with the objective of preventing warping or cupping.
A composite panel which is laminated in a fashion (usually two-sided) that resists warping when subjected to uniformly distributed changes in humidity.
The substance (generally resin) that bonds the fiber together in composite panels.
The application of binder and additives to fiber in the manufacturing of composite panels.
A localized delamination caused by steam pressure build-up during a hot pressing process. This can result from excessive moisture, adhesive (glue) spread, and/or press temperatures.
Voids made by wood-boring insects, such as grubs or worms.
The deviation from flatness along the length of the panel.
A (leafing, shelling, grain separation) separation on veneer surface between annual rings.
A straight joint in which the interface is perpendicular to the panel face. An end butt joint is perpendicular to the grain.
The measurement of board thickness. Also refers to the tool used to measure thickness or diameter.
(See crossband gap)
Inner layers whose grain direction runs parallel to that of the outer plies. May be of parallel laminated plies.
A visible “wavy” condition across the surface width of a panel created when the panel is sanded. Chatter marks are parallel to one another, usually between 1/4″ and 1/2″ apart, and perpendicular to the sanding direction.
A lengthwise separation of wood fibers, usually extending across the rings of annual growth, caused chiefly by strains produced in seasoning.
The amount of material removed by each cutting tooth of a saw blade, router, or shaper, as it moves through the material being cut.
Defect created during cutting/machining when material is torn-away from the top or bottom panel edges.
Class I, II
Term used to identify different species group combinations of B-B concrete form panels.
A machining technique in which the cutting tool rotates in the same direction as the material being cut is traveling.
Composite Panel Association (CPA)
An association of North American producers of MDF, Particleboard, and Agrifiber panels located at 18928 Premiere Court, Gaithersburg, Maryland 20875. (www.pbmdf.com)
Construction (panel construction)
Term referring to detailed manner in which veneers are assembled and/or thickness of veneer used, e.g., “4-ply construction”, “3-layer construction,” “1/10 inch face and back,” etc.
Sometimes referred to as “crossband.”
Delamination of the core, often at the center line, caused by blows or insufficient internal bond.
Inner layers whose grain direction runs perpendicular to that of the outer plies. May be of parallel laminated plies. Sometimes referred to as core.
Crossband Gap and Center Gap
An open joint extending through or partially through a panel, which results when crossband or center veneers are not tightly butted.
A phenomenon in which the center of the panel is thicker along its length than at the two long edges.
Deviation from a straight line across the width of the panel.
Cellulose papers weighing between 40 and 140 grams per square meter in an untreated state. Impregnation with melamine thermoplastic resins can add 20 to 40 grams per meter – depending on the basis weight of the paper. Foils require an adhesive for lamination.
Irregularities such as splits, open joints, knotholes, or loose knots, that interrupt the smooth continuity of the veneer.
The measurement of board/panel “sag” between supports when a load is applied – such as with shelving.
A visible separation between plies that would normally receive glue at their interface and be firmly contacted in the pressing operation. Wood characteristics, such as checking, leafing, splitting, and broken grain, are not to be construed as delamination. See corresponding definition for those terms. For purpose of reinspection, areas coinciding with open knotholes, pitch pockets, splits, and gaps and other voids or characteristics permitted in the panel grade are not considered in evaluating ply separation of Interior type panels bonded with interior or intermediate glue. In evaluating Interior panels bonded with exterior glue (Exposure 1), delamination in any glueline shall not exceed three square inches except where directly attributable to defects permitted in the grade as follows: Delamination associated with: Knots and knotholes – shall not exceed the size of the defect plus a surrounding band not wider than 3/4 inch. In evaluating Exterior type panels for ply separation, the area coinciding with the grade characteristics noted in paragraph (a) are considered, and a panel is considered delaminated if visible ply separation at a single glueline in such an area exceeds three square inches. All other forms of permissible defects – shall not exceed the size of the defect.
The weight of a panel as measured in pounds per cubic foot, or in kilograms per cubic meter.
Gradient density of a panel from face to face.
A concave area in the surface of the panel.
Direction of Grain
Usually refers to the linear direction of a wood grain pattern, or the direction in which a composite panel has moved through a sander.
Dubbing of the End (End Snipe)
Tapering of the edge of a panel as it enters and/or exits a sander.
A low-gloss area on a wet-coated panel usually caused by an incompatible finishing material, a soft panel surface, or excessive pre-heating of the panel prior to coating.
A laminate material which provides a protective decorative surface for panel edges.
Edge Snipe (Rollover)
A narrow tapered condition along the edge of a panel that may be caused when the sander belt width exceeds the panel’s width. Snipe is difficult to spot visually, but can be measured with a caliper.
Wedge-shaped openings in the inner plies caused by splitting of the veneer before pressing.
A process in which the panel surface is given a “relief” effect with a patterned pressure plate in a press.
Equilibrium Moisture Content (EMC)
The state at which the panel neither gains nor loses moisture given the relative humidity and temperature of the surrounding atmosphere.
The face of the plywood panel; the side of a panel that is of higher veneer quality on any panel whose outer plies (front and back) are of different veneer grades; either side of a panel where the grading rules draw no distinction between faces.The face ply of a panel; the outer veneer on the face of a panel.
A dark densified area on the panel surface that may rupture or break upon cutting or machining.
The speed at which material is cut/machined – usually measured in feet or meters per minute.
Fiber Raise (Fiber Pop)
A situation in which the face fibers of a composite panel have raised above the surrounding surface – usually caused by moisture absorption.
A high-solids finishing material used to fill small voids or pits in panel surfaces and edges.
The rate at which flame spreads along the surface of a material as measured in a standard testing procedure. The rating is expressed in numbers or letters as they relate to finishing requirements or building codes. Plum Creek Super-Refined MDF2?, like all unrated MDF products, carries a “class C” rating.
The degree by which a material will compress before being penetrated by a cutting tool.
Thin decorative paper laminates with a melamine topcoat for durability.
A reactive organic compound (HCOH) used to manufacture binders.
MDF mill equipment that forms the furnish into a pressable mat.
The blended wood fiber and binders used in composite panel manufacturing.
Term used to identify panels having special characteristics and/or requirements as described under Section 3.6, such as Marine, Decorative, and Underlayment.
Linear abrasions caused by the sanding process.
A reference to the coarseness of the abrasive material on a sanding surface. The lower the grit number, the coarser the abrasive material.
Term used to classify species covered by this Standard. Species covered by this Standard are classified as Groups 1, 2, 3, 4, and 5. See Table 1 for listing of species in individual groups and the reference in Section 2 for product use information.
A general term referring to hot pressed engineered wood panels made with refined wood and a lignin binder. Additives may be introduced during the manufacturing process to impart certain properties such as stiffness and hardness. The density range is roughly 55 to 75 pounds per cubic foot.
A measure of a panel’s resistance to surface indentation, or impact resistance, which is stated in pounds, and is related to panel density.
Nonactive core of a log generally distinguishable from the outer portion (sapwood) by its darker color.
Heat Transfer Foils
A panel laminating system involving the transfer of a complete coating surface from a carrier film to a substrate by means of heat and pressure.
Heavy White Pocket
May contain a great number of pockets, in dense concentrations, running together and at times appearing continuous; holes may extend through the veneer but wood between pockets appears firm. At any cross section extending across the width of the affected area, sufficient wood fiber shall be present to develop not less than 40 percent of the strength of clear veneer. Brown cubicle and similar forms of decay which have caused the wood to crumble are prohibited.
High Pressure Laminate (HPL)
Built-up sheet laminate constructed of multiple layers of kraft paper saturated with phenolic resin, a decorative layer impregnated with melamine resin, and a clear or tinted thin overlay heavily saturated with melamine resin. The layers are bonded together under heat and pressure to form a very durable surface for use in applications such as counter tops or panel edges.
A composite panel with similar fiber quality and/or density throughout its thickness.
Hook or Rake Angle
Degrees of angle on a cutting tool affecting the ease with which it penetrates the material being machined.
A 100% solid thermoplastic substance used in a variety of gluing and laminating processes. Unlike air-dried adhesives, hotmelts cure as they cool.
Plies other than face or back plies in a panel construction. Sub-face, sub-back, crossband and center are classed as inner plies.
A measure of a material’s resistance to heat flow/transfer stated as “R Value.”
Overall measure of panel integrity illustrating how durably the furnish is bonded together. “I.B.” is generally expressed in pounds per square inch and represents the force perpendicular to the panel surface required to pull a standard test sample apart.
Jointed Inner Plies
Crossband and center veneer that has had edges machine-squared to permit tightest possible layup.
The width of a saw cut.
Natural characteristic of wood that occurs where a branch base is embedded in the trunk of a tree. Generally the size of a knot is distinguishable by a difference in color of limbwood and surrounding trunkwood. Natural characteristic of wood that occurs where a branch base is embedded in the trunk of a tree. Generally the size of a knot is distinguishable by a difference in color of limbwood and surrounding trunkwood abrupt change in growth ring width between knot and bordering trunkwood diameter of circular or oval shape described by points where checks on the face of a knot that extend radially from its center to its side experience abrupt change in direction.
Voids produced by the dropping of knots from the wood in which they are originally embedded.
(n) A decorative overlay. (v) To bond layers of material together with adhesive.
A condition where the veneers are so placed that one piece overlaps the other.
A layer is a single veneer ply or two or more plies laminated with parallel grain direction. Two or more plies laminated with grain direction parallel is a “parallel laminated layer.
Light White Pocket
Advanced beyond incipient or stain stage to point where pockets are present and plainly visible, mostly small and filled with white cellulose; generally distributed with no heavy concentrations; pockets for the most part separate and distinct; few to no holes through the veneer.
Linear Expansion / Contraction
Percent change in the length and width of a panel when exposed to a 50% to 80% change in relative humidity.
Any number of panels considered as a single group for evaluating conformance to this Standard.
Low Basis Weight Paper
Often referred to as “micropapers” or “rice papers” that may range in weight from 20 to 30 grams per square meter, and which are sometimes pre-impregnated with resin.
Low Pressure Laminate (LPL)
A pre-printed or solid-colored decorative paper saturated with melamine resin which, under heat and pressure, is bonded to a panel surface without the need for additional adhesive. The resulting durable surface is featured in a broad range of products from kitchen cabinetry to laminate flooring.
Refined fiber as it is formed and conveyed to the press.
Medium Density Fiberboard (MDF)
An engineered wood product made from mechanically refined wood fibers combined with resin, which are bonded together under heat and pressure. Its typical density range is 40 to 50 pounds per cubic foot (640 – 880 kg/m3). The durable homogeneous construction of MDF resists warping, cracking and splitting – offering unparalleled design flexibility where intricate shaping and finishing are required. Some of the more common uses of MDF include furniture, cabinetry, millwork, store fixtures and laminate flooring. As with solid wood, the nature of MDF can vary significantly between manufacturers, based on wood species and production technology.
A resin formulation used in the saturation of paper overlays which adheres to the panel substrate in hot press lamination.
Modulus of Elasticity (MOE)
The pounds per square inch measure of a panel’s resistance to deflection when loaded as a simple beam.
Modulus of Rupture (MOR)
The pounds per square inch measure of the maximum breaking strength of a board when loaded as a simple beam.
The amount of water in the panel expressed as a percentage of dry weight.
An irregular appearance in an area (or entire surface) of a finished panel which may be caused by coarse or raised fiber, heavy application of coating material, improper drying of coating material, or incompatible solvents. Also known as “orange peel.”
Full “designated” thickness. For example, 1/10 inch nominal veneer is 0.10 inch thick. Nominal 1/2 inch thick panel is 0.50 inch thick. Also, commercial size designation, subject to acceptable tolerances.
Refers to the degree with which finishing material masks the underlying substrate. For example, high opacity indicates more complete coverage.
A thin layer of paper, veneer, foil, or other laminate material.
An engineered wood product made from a combination of wood particles and fibers bonded together with a synthetic resin under heat and pressure. Particleboard is available in a variety of thickness’, sizes and densities and is used in wide range of products where dimensional stability and strength are critical. Particleboard’s machinability and face integrity make it especially well-suited for laminating applications.
Inserts of sound wood or synthetic material in veneers or panels for replacing defects. “Boat” patches are oval-shaped with sides tapering in each direction to a point or to a small rounded end; “Router” patches have parallel sides and rounded ends. “Sled” patches are rectangular with feathered ends.
A water-resistant thermosetting resin used to bond softwood plywood, OSB, and some exterior or moisture-resistant grades of composite panels.
A well-defined opening between rings of annual growth, usually containing, or which has contained, pitch, either solid or liquid.
A localized accumulation of resin in coniferous woods which permeates the cells forming resin soaks, patches, or streaks.
Small voids caused when fibers are torn out of the panel edge or surface during machining or sanding.
The rigid heated surface within a composite panel press that comes into contact with the panel surfaces.
Plugged Inner Plies
(Also referred to as solid inner plies.) – Refers to C Plugged crossband and centers and additional limitations, as given in 3.8.1.
Sound wood of various shapes, including among others, circular and dog-bone, for replacing defective portions of veneers. Also synthetic plugs used to fill openings and provide a smooth, level, durable surface. Plugs usually are held in veneer by friction until veneers are bonded into plywood.
A single veneer lamina in a glued plywood panel. (See also layer.)
Plywood is a flat panel built up of sheets of veneer called plies, united under pressure by a bonding agent to create a panel with an adhesive bond between plies as strong as or stronger than, the wood. Plywood is constructed of an odd number of layers with grain of adjacent layers perpendicular. Layers may consist of a single ply or two or more plies laminated with parallel grain direction. Outer layers and all odd numbered layers generally have the grain direction oriented parallel to the long dimension of the panel. The odd number of layers with alternating grain direction equalizes strains, reduces splitting, and minimizes dimensional change and warping of the panel.
Decorative paper impregnated with polyester resin which is laminated to a backer for flat or contoured applications.
The permeability of the panel’s surface or core to liquid coatings and/or adhesives.
High pressure laminate designed to be hot-formed around a radius where a curved design is preferred over a square edge.
Paper treated (after it has been manufactured) with resin such as urea formaldehyde, melamine, or acrylic which allows the paper to remain flexible – even with the resin fully cured. These papers are easily topcoated and are available with a pre-applied hotmelt adhesive.
Either the premature curing of resin before hot-pressing, or a reference to incomplete sanding of a composite panel.
Paper treated (while it is being manufactured) with resin such as urea formaldehyde, melamine, or acrylic which allow the paper to remain flexible – even with the resin fully cured. These papers are easily printed or heat embossed, and are available with a pre-applied hotmelt adhesive.
A cold press in the MDF manufacturing process following the “former” that consolidates the fiber prior to hot pressing.
Heated platens in the MDF manufacturing process which consolidate the pre-pressed mat into a panel.
Primary Grit Marks
Linear scratches in the face of a panel from coarse sanding which are not removed by subsequent finish sanding.
The three-dimensional shape of a machined panel edge or face.
Pounds of force per square inch of panel surface.
A ratio comparing the amount of water vapor present in the air to the amount which saturated air would hold at the same temperature.
Any patch, plug, or shim.
Hard pieces of dark or black material in the face layer of an MDF panel composed of resin and wood dust.
Grain characteristics which prevent sanding to a smooth surface.
A rough area of a panel that was not sanded with the finish heads.
The revolutions per minute speed of a motor or cutting tool.
An unsanded corner or edge of the panel (which is thicker than the rest of the panel) that may appear discolored.
Concave linear “troughs” across the width of a panel caused when the panel stops under a moving sander head.
A portion of the panel surface which wasn’t sanded, usually appearing as a rough concave area.
A situation in which the panel face layer or laminate has been sanded off exposing the core.
The living wood of lighter color occurring in the outer portion of a log. Sometimes referred to as “sap.”
Decorative papers generally weighing between 60 to 120 grams per square meter which are saturated with melamine or polyester resin, and partially cured at the point of its manufacture. Final curing occurs during hot press lamination.
The standardized test measure of force in pounds required to extract a screw from the face or edge of a panel.
A long, narrow repair of wood or suitable synthetic not more than 3/16 inch wide.
A shop-cutting panel is one which has been rejected as not conforming to a standard grade because of deficiencies, other than adhesive bond quality, which prevents it from meeting the requirements of this Standard. Blistered panels are not considered as coming within the category of “shop-cutting” panel. Localized delamination may occur as a result of a deficiency. However, shop-cutting panels may be suitable for cut-up use where cutting eliminates the deficiency in the portion of the panel salvaged. Such a panel must be identified with a separate mark as specified in 6.2.1.
Serpentine raised marks on the face of the panel running along its length caused by buildup or skips on the sander belt.
Solvent Borne Adhesives
Solutions of polymers, volatile organic solvents, and crosslinking materials designed to obtain specific properties in the laminating process, such as a heat-resistance bond.
A set of numbers used in marking sheathing and combination subfloor-underlayment (single floor) grades of plywood as described in 3.8.5. Formerly called Identification Index.
Lengthwise separation of wood fibers completely through the veneer, caused chiefly by the manufacturing process or handling.
The degree to which a compressed MDF panel returns to its original uncompressed state.
Panels featuring right-angled corners or equal corner-to-corner diagonal measurements.
Insufficient adhesive spread in the lamination process.
The difference in height between adjoining panels due to thickness variation.
See “Pitch streak.”
The ply adjacent to the exposed face (or back) of a parallel laminated outer layer.
The platform upon which adhesive, laminate and/or other finishing material is applied.
Thickness increase in a panel due to moisture absorption or wetting.
The maximum pounds per square inch of longitudinal stress a material can resist without tearing apart.
Thermally Fused Melamine
Paper saturated with melamine resin which is thermally fused to the substrate.
A finishing process in which a flexible laminate, such as vinyl film, is vacuum-formed over a three-dimensional surface in a heated press.
Adhesives that cure at room temperature and soften upon exposure to heat.
Adhesives that cure in a hot press via chemical crosslinking to form rigid bonds that are not re-softened by subsequent exposure to heat.
Thickness variation within a panel, or between panels.
A sizing operation consisting of a light surface sanding in a sander. Sander skips to any degree are admissible.
Use of two different laminates or finishing materials on the front and back of a panel that respond unequally to changes in moisture, thus increasing the risk of warp.
Weight distributed evenly across a shelf or panel.
Urea Formaldehyde (UF)
Interior grade thermosetting resin commonly used in the composite panel manufacturing process.
Thin sheets of wood of which plywood is made. Also referred to as “plies” in the glued panel.
A flexible polyvinyl chloride laminate used for decorative surfacing which may be either clear or solid-colored.
Thin to open areas in veneer sheets that result from outer log surface irregularities. Generally, only veneer peeled from the outer log surface will contain wane. Some wane areas may contain bark inclusions. For grading, wane is classed as an open defect.
Bending, twisting or turning of a panel due to unbalanced construction, exposure to excessive moisture, or other unfavorable conditions.
Water-soluble adhesives such as urea formaldehyde and vinyl acetate commonly used in paper lamination.
For purposes of this Standard, glue capable of bonding plywood in a manner to satisfy the exterior performance requirements given herein.
A form of decay (Fomes pini) that attacks most conifers but has never been known to develop in wood in service. In plywood manufacture, routine drying of veneer effectively removes any possibility of decay surviving. (Admissible amounts of white pocket permitted by this Standard were established through a 2-year research project at the U.S. Forest Products Laboratory.)
Wood failure (percent)
The area of wood fiber remaining at the glueline following completion of the specified shear test. Determination is by means of visual examination and expressed as a percent of the test area.
Solid wood laminate in a “flat,” “quarter,” “rift” or “rotary” cut.
Decorative Laminates Glossary
2 Mil Reverse Printed Rigid Film
Unembossed, extruded or calendered rigid PVC. The print design and ground coat are printed on the back of the film in reverse order (reverse print). Used for paneling, Kitchen cabinets, furniture and Mobile homes.
Semirigid Clear Film
Calendered semirigid PVC. This film is reverse printed on the back of the film. It can be embossed and can be coated with scuff-resistant coatings. This film ranges from 4.0 to 8.0 mils in thickness. This film can be mitre folded.
Calendered, semirigid two-ply laminate. This opaque base film is top printed and a clear overlay is laminated over the top. It is designed for mitre folding and flat sheet lamination. It is sometimes available with a scuff-resistant coating. This film ranges from 4.0 to 8.0 mils in thickness.
Solid Color Film
Calendered, semirigid film that is custom color matched in a variety of hues. This film is integrally colored and can be top printed and/or embossed. Top printed film is used in mobile homes, RV’s, commercial paneling and moveable walls. Solid color film is used in furniture, fixtures and displays. Kitchen cabinets and Office furniture. This film is sometimes available with a scuff-resistant coating. This film ranges from 3.5 to 8.0 mils in thickness.
Thermoformed Overlay Films
Calendered or extruded solid color rigid film in single-ply and two-ply construction. Gauges range from .010” to .030”. It may be printed in woodgrain or decorative patterns. Film is sometimes embossed and may be coated with scuff and stain resistant coatings. Primers for adhesion are available. This film is designed for thermoforming with heat and pressure in a bladder press or vacuum forming process.
Calendered or extruded rigid vinyl films in gauges from .005” to .010”. Film may be printed in woodgrain or decorative patterns. It may be embossed and may be coated for scratch and stain resistance. Primers may be added to promote adhesion. This film is designed for wrapping profiles and can be flat laminated and miterfolded.
Low Basis Weight Papers
Low Basis Weight Papers
– Sometimes referred to as micro-papers or rice papers. These papers range in weight from 23 to 30 grams and are sometimes preimpregnated with resin. Acrylic, polyester and other resins can be added during the paper making process to improve the internal bond strength of the paper. The paper is then printed and then coated with polyurethane, urea, polyester acrylic or melamine resins.
Low basis weight papers are usually divided into two categories; standard and industrial. Standard grade papers contain a lower amount of resin in the base paper and offer an economical laminate for use on lower wear surfaces; such as wall paneling. Industrial grade papers have a higher resin content and greater internal bond strength.
Cellulose papers weighing 40 to 140 grams per square meter, untreated. The papers may be impregnated with melamine thermosetting resins or left untreated. Treating may add 20 to 40 grams of weight. Decorative foils require an adhesive for lamination.
These papers are referred to as “finished foils” in Europe. In the U S they are referred to as melamine papers, intermediate weight foils or impregnated foils. Impregnation has a direct effect on the internal bond strength of the paper, as well as the porosity and machinability of the laminated material.
Usually untreated papers; although a small amount of resin may be added. These papers are usually top coated with a varnish.
These papers are treated during the paper making process. They are usually treated with melamine and/or Urea formaldehyde. Additionally, they are usually treated with acrylic, which allows the sheet to remain flexible after the resins are fully cured. The resins are calendered. These papers can be chemically embossed and they may be available with pre-applied hot melt adhesives.
These papers are treated after they have been manufactured. They are usually treated with melamine and/or urea formaldehyde. Additionally, they are usually treated with acrylic, which allows the sheet to remain flexible after the resins are fully cured. With post-impregnated papers, the paper fibers are encapsulated with resin. The voids and air spaces in the paper are filed with resin. These papers may be top coated and they may have hot melt adhesives applied.
These papers usually weigh between 60 and 130 grams. These papers are saturated with reactive resins and are partially cured. Final curing occurs at the time of hot press lamination. This is when the resins form a hard cross-linked thermo-set material; thus creating a permanent bond with the substrate. The decorative paper is similar to that used for high pressure laminate.
Melamine (Thermofused Melamine, TFM or Low Pressure Laminate)
The paper is impregnated with a melamine or a urea-melamine resin system; then partially cured to a “B” stage. The resin is fully cured when the paper is pressed at 300-400 psi, at a temperature of 300-400 degrees F.
The resin is introduced to the paper during an impregnating process. The impregnated paper is then dried. The resin is fully cured when the paper is pressed at 175-200 psi, at a temperature of 275-300 degrees F.
The typical construction of a continuous laminate consists of: a melamine-impregnated alpha-cellulose overlay on top of a decorative surface paper, superimposed over one or more phenolic or melamine resin impregnated papers. The laminate is formed on a continuous, double belt press at pressures of 125-570 psi and temperatures of 275 to 300 degrees F. The thickness is determined by the number of layers of Kraft papers and the resulting amount of resin that is absorbed, is normally 1/32” thick. The surface finish is achieved by using and transferring the texture from a steel caul plate or release paper.
High Pressure Laminate (HPL)
HPL is constructed by sandwiching a decorative surface paper between a melamine impregnated alpha-cellulose overlay and a layered stack of phenolic resin impregnated Kraft papers. The sandwiched papers are pressed at temperatures exceeding 265 degrees F and pressures of 1,000 and 1,400 psi. The thickness is determined by the number of layers of Kraft papers and the resulting amount of resin that is absorbed. The surface finish is achieved by using and transferring the texture from a steel caul plate or release paper.
Heat Transfer Rolls
These foils involve the transfer of a complete coating system from a carrier film to a substrate by means of heat and pressure. The foils are gravure printed in reverse sequence on a Mylar film. The release coat is printed first, followed by the pattern of a wood grain print, the ground coat and the adhesive. These foils provide both a decorative effect, as well as a protective layer.
This edgebanding utilizes vinyl laminated to vinyl, ABS or a paper backer. The carrier is generally rigid clear or colored PVC that is .010” to .030” thick. The surface is usually a reverse printed or solid color vinyl that is .002” to .008” thick. This edgbanding is rigid enough for automatic edgebanders and is suitable for straight-line or softform applications.
An extruded or calendered thermoplastic edgebanding made of polyvinyl chloride; used to match vinyl, paper, paint or HPL. Calendered PVC is manufactured in wide logs and slit to size. Extruded PVC is manufactured to exact width. PVC is available in numerous colors, patterns and woodgrains. A wide range of widths, thicknesses and surface textures are available. PVC is usually top coated with a UV cured resin for protection. PVC is used in straight-line, as well as contour automatic edgebanding applications. PVC is not recommended for softform applications.
Polyester Laminate Edgebanding
Decorative papers, often matching HPL designs and colors, are impregnated with polyester resins and laminated to a variety of backers. This edgebanding is produced in logs and can be slit to any width. A range of finishes are available. Polyester edgebanding is produced in light weight and heavy weight versions. The heavy weight version is excellent for straight-line, contour and softform automatic edgebanding applications.
The term “melamine edgebanding” covers a broad range of paper edgebanding materials, including: single layer printed products, laminated foils and continuous melamine laminates. It is produced in master logs and can be slit to virtually any width. Usually found in Europe, melamine edgebanding is an economical pre-glued and automatic product. It is suitable for straight-line, contour and softform applications.
This category includes textured metals (brushed, polished, matte, etc.) or metallic transfer foils laminated to a backer in a master log. The material can be slit to virtually and width. This decorative edgebanding may be used as an inlay.
Real Wood Veneers
These real wood veneers include a variety of domestic and imported hardwood (and some softwood) species that are available in different cuts (flat cut, rift cut, quarter cut, etc.). These veneers are sliced from 1/25” to 1/50” thin. They are available with plain, paper or fleece backs; with varying degrees of flexibility. The veneers may be finger or butt jointed, to produce continuous edgebanding. Veneer edgbanding is suitable for straight-line, contour and softform automatic applications.
Reconstituted Wood Strips
Man-made veneers manufactured in Europe or Asia. Light colored woods (Usually Ayous, Obeece, Koto or Italian poplar) are peeled, clipped, dyed and then re-glued into a rectangular block that is molded for the different cuts (flat, quartered, etc). The block is then re-sliced into leaves and slit to varying widths for edgebanding. These veneers can be produced into paper back or fleece back strips or coils for straight line, contour or softform automatic edgebanding applications.
See composites glossary.
A two-component thermosetting adhesive typically used for laminating medium and heavy gauge vinyls. Epoxy adhesives are generally bonded 1:1 (resin to hardener) by volume and are roll-coated to either the backside of the vinyl web or to the board surface. Wet lamination is followed by stack curing the panels from one to three days at temperatures above 50 degrees F. Solvent containing epoxies typically have better green strength (wet tack) than 100% solid systems.
An adhesive which is a 100% solids thermoplastic and is applied molten to form a bond upon cooling. Hot melts differ from conventional liquid adhesives because they set by cooling, rather than by absorption or evaporation. In practice, papers are pre-coated with hot melt by the manufacturer; the hot melt is later reactivated by heat when the paper is laminated to substrate on the laminating line.
An adhesive containing polymetric materials dissolved in volatile organic solvents. A small percentage of the cross-linker is added to obtain certain desired performance properties (i.e., higher heat resistance). This type of adhesive is typically used on a “hot line” laminator where it is applied in 2 coats to the board surface, dried and then heat activated prior to hot rolling the laminate to the substrate. Solvent borne adhesives offer good coatability, high heat resistance and excellent bond strength when laminating 2 mil and 4 mil solid vinyl films. When applied to composite substrates, solvent borne adhesives create little to no grain raise.
Water borne adhesives include both thermosetting urea formaldehyde systems, as well as formulated synthetic latex (usually vinyl latex) types. These adhesives are generally used for paper laminating, where the adhesive is applied to the web and/or board surface and tacks up through one or more heated rolls that combine the paper to the board. Water based vinyl acetate/ethylene (VAE) copolymer adhesives are often used for laminating 2 mil and 4 mil vinyl films to various board surfaces.
Heat Seal Adhesives
These are systems are dry coatings on the back of flexible laminates. They are heat sealed to panels by rollers or quick presses at low temperatures and low pressures. They are applied and dried by the laminate producer, using water or solvent based polymers. Heat seal adhesives differ from hot melts in chemistry. They do not reflow upon heating. Also, they do not change with age. They adhere to most surfaces and they form a very tough bond.
Pressure Sensitive Adhesives
Pressure sensitive adhesives are viscoelastic materials coated on a release liner and sold in roll or sheet form. The adhesive is sticky to the touch and can be applied to most surfaces with light roll pressure. Pressure sensitive adhesives bond through intermolecular forces of attraction between like or unlike surfaces, which resist separation.
The highest performing, longest aging adhesives are usually cross-linked high molecular weight acrylic materials. Pressure sensitive adhesive backed veneers are easy to apply and require no liquid adhesives.
Dry Film Bonding Adhesives
Dry film bonding adhesives are non-tacky elastometric materials coated on a release liner and sold in roll form. The film adhesive is bonded to the edge backing material with low temperature heat and low pressure. The adhesive backed material is then heat-bonded at a higher temperature and thermo-set to the application surface.
Polyurethane Dispersions (PUD’s) are aqueous dispersions of fully reacted urethane polymers containing hydrophilic anionic, cationic or nonionic groups noted for their high performance properties, excellent adhesion, chemical resistance, outstanding toughness and low pressure flexibility.
PUD’s are used for the membrane pressing of vinyl films and veneer to an MDF core. PUD’s can be used in conjunction with a hardener for higher heat resistance, if required.
PUD’s are usually applied by spraying on the MDF, air dried and then mated with the vinyl film or veneer in a membrane press. Typical membrane press temperatures range from 158 to 194 degrees F with cycle times of 20 to 120 seconds.
Surface Preparation Equipment
The purpose of this equipment is to properly prepare particleboard, MDF and other substrates for successful lamination. When correctly used, this equipment produces a product surface that will be and dust free. Some applications require the board to be warmed before lamination. This will limit telegraphing of dust and fibers.
Sanding is used to prepare a substrate’s surface for lamination. It is particularly important when particleboard and MDF are used, in conjunction with thinner overlays. The two primary types of sanding equipment used in flat panel lamination are: Contact drum sanders and platen head wide belt sanders. Drum and stroke sanders, although available, are generally not used in flat panel lamination.
Sanding the substrate is usually completed at the beginning of the preparation process. If it is necessary to fill the board, a second sanding may take place, in order to insure that the board is totally smooth before sanding.
The purpose of the panel cleaner is to remove dust and chips from the board surface after sanding. This process usually involves a sweeper vacuum type of equipment. Brushing equipment may be used, in order to separate small particles from the board.
The equipment is used to fill void areas on the board surface. Filling requires oven curing and sanding of the filled surface to insure a successful bond between the board and the overlay. The most common types of filling are ultra violet (UV) curable, waterbase and solvent base.
Board Drying Equipment
-Drying equipment is used to dry and cure any filling agent used to make the substrate smooth. The most frequently used systems are: high intensity infrared, high velocity air and UV curing oven.
Board Preheating Equipment
This equipment is generally used in cold climates. The purpose is to stabilize the entire board surface for successful, consistent laminating, year-round.
Resonating occurs when a panel (PB, MDF, etc.) is passed under high pressure between two polished steel rollers that are heated to relatively high temperatures. The process causes the two resins (specie and added) to become liquid for the instant of pressure. The resin is calendered under the influence of the polished steel rolls and pressure. Crushing of the substrate’s top wood fiber cells occurs during this process.
Resonating improves sanding grit effectiveness or eliminates sanding altogether. This process can be used prior to laminating on either wet or dry systems.
The purpose of coating equipment is to provide a thin layer of adhesive that will bond an overlay to a substrate. Adhesive is applied to the board, to the web or to both. There are a variety of coating systems.
When using a water based adhesive, part of the moisture is flashed off before laminating takes place. This aids in minimizing or eliminating fiber-pop or telegraphing after lamination.
Flat Panel Laminating Equipment
Liquid Adhesive Roll Laminating Equipment
The roll laminating equipment consists of one (sometimes two or three) heated roll combining stations, where continuous rolls of paper or vinyl film are laminated to the substrates. The liquid adhesive is applied to the board, to the web or both. The lamination and bond are created as paper or film is pulled from an unwind stand and is married to the substrate as they meet and pass through the rotary roll combining station.
The equipment can be designed for single or double sided lamination.
Heat Reactive Roll Laminating Equipment
Heat reactive equipment utilizes decorative overlays that have a dry adhesive already applied to their backs. The laminating machine contains heated rollers which activate the adhesive, roll the overlay onto the substrate and apply pressure while the bond is created. There are no curing ovens required in this process. Bonding and curing are rapid.
Continuous Belt Roll Laminating System
The continuous belt roll laminating system is a more sophisticated equipment arrangement. Panels (particleboard, MDF, hardboard, etc.) are fed into the line, continuously, end to end. The overlays are applied from rolls to the adhesive coated substrate, on one or both sides, prior to bonding. Depending upon the adhesive system used, the process (bonding) may be completed by using either hot or cold calendar rolls.
Hot Platen Press
Hot platen presses are internally heated single opening or multi-opening presses with flat or molded platens. The pressing times and the temperatures are determined by the adhesive, chemical and/or heat reactions. The thickness and composition of the core influence the pressing times and temperatures, as well.
A glue spreader is usually used to apply common adhesives. The adhesives used are urea formaldehyde, PVA, PVAC and phenolic resins.
Low Pressure Press (TFM)
This system earned its name from the distinction between high pressure lamination, which utilizes pressures between 700-1400 PSI, and low pressure lamination, which utilizes pressures between 350 and 400 PSI. Low pressure lamination is a process whereby the resin saturated films are pressed onto the substrate (particleboard or MDF) with a pressure of 350+ PSI and a temperature of about 350-400 degrees F.
The resin is the bonding material. The resin liquefies under heat and pressure and is thermofused directly to the core. The resins form a firm cross-linked thermo-set material. The surface texture of the final product is set by the caul plates (or sometimes release papers), which are fixed to the hot press platens. The most common resin is melamine. Polyester and phenolic surface films are sometimes pressed. Phenolic resin films are mainly used on concrete form.
– Membrane press technology, formerly known as the vacuum press system, is used for the lamination of molded (three-dimensionally shaped) substrates with veneers, vinyls and other materials. The adhesives are applied either to the core or to the laminating materials. The pressing process is performed with a silicone or rubber membrane, which forms the laminating material under pressure and heat over the molded substrate. In a membrane press, heat is applied to both the top and bottom. Pressure is applied only to the top and a vacuum is drawn from the bottom. The pressure used to complete the laminating process is about 105 lbs per Square inch.
The adhesives used for veneers are primarily PVA and urea formaldehyde. Vinyls are usually bonded with water based polyurethane, which is dried after application and reactivated during the pressing process.
Vacuum presses are used for lamination of molded (three-dimensionally shaped) substrates with vinyls and other materials. The adhesives are applied to either the core or to the laminating materials. The pressing process uses a silicone or rubber membrane, which forms the laminating material under pressure and heat over the molded substrate.
In a vacuum press, heat is applied to the top of the press, while a vacuum is drawn from the bottom. Since only the atmospheric pressure is involved, the laminating process operates in the range of 26 lbs per square inch at sea level.
Vinyls are usually bonded with water based polyurethane, which is dried after application and reactivated with heat during pressing.
The cold press system has the advantage of being a smaller investment and utilizes less complicated technology but it does require a longer pressing time. This system is usually used for HPL and other phenolic backed laminates.
Adhesive (PVA) is applied with a glue spreader onto the substrate. Laminate is placed onto the substrate. The substrate and laminate unbonded panels are stacked and placed into the cold press, where pressure is applied for 30 to 60 minutes.
Surface Foiling Equipment
This equipment takes a heat transfer foil and transfers it to the surface of a smooth substrate. The foil is transferred from the carrier film through heat and pressure. Because the foil is very thin, it is important that the surface is extremely clean of dust and other lose particles.
There are three additional foiling machines that can cover board surfaces, as well as their edges: bluff cut machines, random foilers and molding foilers.
Edge Laminating Equipment
The function of edge laminating equipment is to provide a finished edge to a panel or a potion of a panel that has been surface laminated. A product with the porosity of particleboard may need to be edgebanded with a band thick enough to conceal the voids between the particleboard. Sometimes homogeneous cores with heavier density, such as MDF, can be banded with standard edge treatments or heat transfer foils.
These are single or double sided machines that typically shape, sand and foil to a straight or profiled edge. The foil is transferred by heated silicone wheels, using pressure to match the desired edge profile. MDF is the most common substrate used with edge foiling.
Edgebanders apply PVC, HPL, melamine, polyester, solid wood and wood veneers to the edges of panels. Types of edgebanders include: single and double-sided machines, hot air, PVC, contour, straight-line and softforming variations. Edgebanders can be manual or automatic. They can apply edgings with or without coated adhesives. Many larger edgebanders have front end tenoning capabilities for sizing and shaping.
– Single and double sided softforming edgebanders are capable of applying either a flat or a shaped edge, such as an ogee. Most softformers have sizing and shaping stations, which mill the edge prior to the application of the edgebanding. Softform edgebanders can utilize either PVA or hot melt adhesive systems.
Profile wrap machines apply an overlay to a preformed substrate, typically in pre-shaped molding form. The substrate is usually MDF but can be particleboard, solid wood, extruded plastic or metal. A flexible overlay, such as paper, vinyl, wood veneer or a metallic foil is applied to the surface of a molding. These machines usually utilize hot melt or PVA adhesives.
There are three ways of putting a soft, radiused edge on a panel. Softforming and profiling are two of the methods. The third method is conventional postforming. This is the process where a laminated surface is formed to a shaped substrate material. There are two types of machines that are used for conventional postforming; stationary and through-feed.
Stationary machines will utilize a heated bar which follows the pre-shaped substrate. Contact adhesives or PVAC glues can be used with this machine. Stationary machines can use a variety of substrates and are easy to set up and operate.
Through-feed postforming machines are used where higher production rates are required. These postformers incorporate more automated stations or zones (sizing, adhesive applications, activation, forming and trimming).
Direct postforming involves the same processes as conventional postforming, with the exception being that the substrate is pre-shaped on the postforming machine. These machines require fewer processing stations than conventional postforming machines.