XXVI. MANUFACTURE OF INSULATION BOARD AND PRESDWOOD BY THE MASONITE PROCESS ROBERT M. B o E ~MASONITE . CORPORATION, LAUR&L. MISSISSIPPZ The Masonite Process, which converts wood waste into Insulation Board, Quartrboard and Presdwood by means of an explosion process, has attracted a great deal of attention both because of the novelty attached to shredding wood by rupturing it internally under the influence of extremely high steam pressure and because of the economic importance of an industry which utilizes a waste material and converts it into products of great commercial value. In the last four years the Masonite Corporation has developed from a theory into a commercial plant with an annual capacity of over 130,000,000 square feet of boards. The products are Insulation Board, Quartrboard, 3/16 Presdwood, and Presdwood. Insulation Board is inch thick and weighs 750 pounds per thousand square feet; Quartrboard is '/r inch thick and is of the same weight; ' / ~ e Presdwood is 3/16 inch thick and weighs 1000 pounds per thousand square feet; Presdwood is inch thick and weighs 750 pounds per thousand square feet. The specific gravity of Insulation is 0.300, of Quartrboard is 0.600, and of Presdwood and Presdwood is 1.10. The tensile strength of Insulation Board is over 200 pounds per square inch, of Quartrboard over 500 pounds per square inch, and of 3/16 Presdwood and Presdwood over 4000 pounds per square inch. All these products are made in large 4 foot X 12 foot panels. Masonite Insulation is widely used for its insulating and acoustical properties. Quartrboard, because of its insulating value and structural strength, is incorporated into many pieces of equipment as an integral part of the structure. Presdwood is an entirely new article of manufacture and is produced only by Masonite. It is in many ways the most interesting and unusual development in the board industry. I t is extremely hard and dense and one surface is very smooth, lending itself perfectly to any type of decoration. I t is extremely water resistant and this, added to its great strength and rigidity, makes it very valuable as a structural material. It is impossible to enumerate all of the uses of Presdwood. It is rapidly replacing wood for conaete forms, for when the Presdwood is stripped from the form, the concrete is smooth and without defects and requires practically no further work. Furthermore, the Presdwood may be reused several times. Presdwood is used extensively in the automobile 2387
F I G U17.-A ~ HUGEREFUSEBURNER,WAICHHASREENIDLEPOR OVER 5 YEARS The lettering on this monument to waste reads: "Even, day during my life of ~ i x t years e ~ I consumed daily 560 cords of waste wood, or a total of 2,688,000 cords. I cost $75,000 but my 6re has destroyed 51,344,M)O worth of what was formerly considered waste. The complete utilization of sawmill refuse in the ~~.-..c.-*
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and moving picture industries. It is also perfectly adapted for the construction and remodeling of homes and buildings. At present the Masonite Process utilizes long leaf pine waste but experiments prove that any type of wood waste is suitable. The wood is reduced by chippers and hogs to chips approximately 0.75 inch long. These are screened to remove sawdust and slivers and are fed directly to the guns. The guns are 20 inches in diameter and 5 feet high and are equipped with quick-opening hydraulic valves. When the gun is loaded with chips, low pressure steam is admitted a t 350 pounds per square inch. They are left at this temperature for thirty to forty seconds and the high pressure steam is then admitted which brings the pressure up to 1000 pounds per square inch. Five seconds later the discharge valve is opened and the chips pass through a port in the bottom of the gun and explode immediately, due to the high internal pressure. This completely ruptures the chips and produces a mass of long fiber bundles. The fiber is refined by passing through rod mills and other refiners, during which time the consistency, temperature, and pH are carefully controlled. It is waterproofed with a sizing emulsion and passes directly on to the forming machine. Here it is formed into a continuous wet lap 0.75 inch thick and slightly over 4 feet in width. The wet lap is cut into 12.5 foot lengths and fed into large hydraulic presses. These presses are equipped with steamheated platens, a wire screen on which the wet lap is inserted and removed, and a polished chrome plate which imparts hardness and luster to the surface. In the manufacture of Insulation Board and Quartrboard. the presses are equipped with stops to hold the board a t the desired caliper. In the manufacture of Presdwood, the full pressure of 300 pounds per square inch is applied to the board. This causes the fibers to become bard and glassy and to weld together into an extremely dense, strong product. The boards then pass through a humidifier which is maintained a t 80' F. and 100 per cent relative humidity. This equalizes the moisture content of the boards to 7 per cent, insuring a moisture equilibrium and preventing expansion and contraction in usage. From ten to twehe hours in the humidifier is necessary to obtain this result. A chrome-plating plant has been installed to plate and polish the large plates which are used in the presses to give Presdwood its dense, smooth surface. Smce we are practically pioneers in the chrome plating of objects of this size, a great deal of original work was required. The control of the entire process is carefully watched from the wood and other raw material to the finished product. The wood is tested for moisture, bark, and imperfections. The guns must be watched very
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closely, since when dealing with pressures of this magnitude slight changes are very important. The refining is carefully watched and the fibers compared with standards which have been set up. Machine operation, press operation, and the auxiliary processes such as the humidifier, chrome plating plant and converting and finishing are carefully controlled. The finished board is subjected to routine tests for weight, caliper, moisture, water absorption, transverse strength, deflection, tensile strength, bond strength, and specific gravity as well as periodical tests which demonstrate its suitability for various applications. Throughout the process, water is used as a conveying medium. This water is carefully controlled for temperature, pH value, and concentration of suspended and dissolved solids. A clarifying system is in operation which removes the bark and other undesirable materials and allows the water to be re-used, thus conserving the heat and the dissolved solids. A large research department is maintained which may be subdivided into four main classes. These are technical control, mill research, fundamental research, and development. The research department is equipped with a complete semi-commercial apparatus as well as departments devoted to chemical analyses, physical methods, optical analyses, testing of machines and instruments and studies of applications. The Masonite Corporation feels that only by intensive research activities can it continually advance the quality of its products and continue to maintain its present position in the industry.
