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Related to Molding: Molding sand, injection molding, Molding Materials
molding,in architecture, furniture, and decorative objects, a surface or group of surfaces of projecting or receding contours. A molding may serve as a defining element, terminating a unit or an entire composition (e.g., in the cap of a column or the crowning cornice of a building) or establishing a boundary or transition between portions of a design. One of the primary considerations in the design of a molding is the type of shadow it will cast. The shape of a molding is termed its profile or section. Moldings formed an important part of most past styles; in Babylonia, Assyria, and Persia, however, their place was taken by flat ceramic enrichments in color. In Egypt, moldings were limited to the cove, or cavetto, and the half round, or torus, which, used together, formed the cornices for the walls of temple or pylon. Moldings were an essential feature of Greek orders and buildings. The Greek profiles form the basic molding vocabulary for classic types such as the fillet and the fascia, flat vertical surfaces; the ovolo, of an egglike convex outline; the bead and the torus, both convex, three fourths of a circle and one half, respectively; the cavetto, a quarter circle, and the scotia, of elliptical curvature, both concave; and the cyma recta and the cyma reversa, both of compound curvature, being half concave and half convex. The ovolo was carved with the alternating egg and dart; the acanthus leaf and the anthemion were used for the cyma recta, or ogee, and the water leaf for the cyma reversa. Roman designers, substituting simple segments of circles for the elliptical and parabolic curvatures, never attained the beauty of Greek forms, although in ornament they added numberless innovations. In Byzantine architecture the tendency was to flatten the classic outlines, transforming them into bands of pierced enrichment. Romanesque moldings were chiefly simple segments of a circle, as in the especially characteristic boltel, or three-quarter round. Moldings changed with the development of Gothic architecture. Cornices, jambs, archivolts, and capitals show a richly varied interplay between projecting rounds and deep concavities. In the late Gothic (15th cent.) of France and Germany there were ingenious combinations of differing elements to produce broken, merging, and interpenetrating moldings. In developed Gothic a rich assortment of naturalistic forms appeared, e.g., flowers and intertwining vines. The Renaissance return to purely Roman forms was followed in the baroque by heavier, projecting moldings, which cast dramatic shadows. Later a wide variety of styles was employed, but since the 19th cent., decorative molding has been little used in modern architecture.
bead and reel molding
blind stop molding
cyma recta molding
cyma reversa molding
flush bead molding
hollow square molding
quirk bead molding
a contoured woodworking lath (bar, plate) designed for covering grooves in joints (such as those between a floor and a wall), projecting ribs and edges, such as those in furniture, and so on. Moldings also include pieces for rounding off internal and external angles of machine parts, casting forms, and the like. Moldings simplify production and treatment of parts and prevent crack formation in places of joining.
an elongated architectural element of various sections (profiles) that usually appears horizontally on a socle, a cornice, a string course, or the base of a column. Some moldings are inclined (pediment cornices), curved (archivolts, ribs), or broken (door and window frames).
Moldings are most widely used in architecture employing the classical orders. They reflect the distinctive stylistic features of the stone architecture of different peoples and epochs and, for that reason, are often regarded solely as architectural decoration. In a number of instances, however, moldings serve to emphasize the structural design of a building.
Moldings acquired special significance in ancient Greece. Together with the classical orders, they were borrowed by Roman architecture and, later, by Renaissance architecture and European architecture of subsequent periods.
In modern architecture the term “profile” tends to replace the word “molding” in reference to metal, concrete, and wooden elements on the facades of buildings (transoms and the frames and string courses of curtain-wall panels). By slightly altering the combination, curvature (classical moldings were either rectilinear or curvilinear in section), and projection of moldings, architects are able to vary the effect created by the top or base of a building and alter the relationship between a building’s various parts. For example, the projection and height of the molding emphasize the heaviness or lightness of the parts of the building above the molding.
REFERENCESSultanov, N. Teoriia arkhitekturnykh form: Kamennyeformy. St. Petersburg, 1903.
Mikhailovskii, I. B. Teoriia klassicheskikh arkhitekturnykh form, 3rd ed. Moscow, 1944.
Shoe, L. T. Profiles of Greek Mouldings. Cambridge, Mass., 1936.
V. F. MARKUZON
in founding, the process of producing the mold used to obtain a casting. Hand molding is used primarily for single castings and for short-run production; machine molding is used in series, large-lot series, and mass production.
Hand molding may use casting patterns (for both pit molds and flasks), sweeps, skeleton patterns, and mold cores.
Pit molds are used to produce large, heavy, single castings. In pit molding, pits and concrete caissons that protect the mold from groundwater are constructed in the floor of the shop. A layer of gas-permeable material, called the bed, is placed on the bottom of the pit and caissons. Soft beds of friable mixtures of sand and clay are used in the production of small castings; they feature vents, formed in the sand by a curved, steel vent pin, for carrying off gases formed during molding. Hard beds made of slag or similar materials are used in the production of large, heavy items; their gas vents are formed by steel pipes. Pit molds may be open or closed. In the former, the mold is completely below the level of the floor; in closed molds, the lower half of the mold is beneath the floor level, and the upper half is exposed. Such two-piece molds are used when the upper surface of the casting must meet more stringent specification for surface roughness. The disadvantages of pit molding are high labor input and poor casting accuracy.
Hand molding in flasks is used to obtain small sets of castings of a single type. Sweep molding is advantageous in the production of large, single castings that have the form of bodies of rotation, such as basins, covers, and pulleys; the technique makes it possible to replace expensive patterns made of solid wood with flat, wooden, figured templates that, when rotated about a spindle axis, form the cavity of the casting mold. Skeleton molding is a type of template molding. In this case, the bulky pattern of solid wood is replaced by a shaped frame, the cavity and cells of which are filled with molding sand prior to the molding process. Core molding is used to produce castings with very complicated designs when pattern molding is not economical. The outer and inner outlines of the casting are formed by cores constructed in prefabricated metal or nonmetal jackets.
Machine molding permits the partial or complete mechanization and automation of the operations for the production of molds and ensures higher quality and accuracy of the castings. Machine molding is done on various molding equipment, including automatic transfer machines.
REFERENCESosnenko, M. N., and B. K. Sviatkin. Obshchaia tekhnologiia litei-nogoproizvodstva. Moscow, 1975.
M. N. SOSNENKO