• Journal of the Korean Wood Science and Technology
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• v.13 no.3
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• pp.3-26
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• 1985

The object of this study was to investigate the effects on physical and mechanical properties of wood particle and sawdust board combined with wire net. Conventional forming, press-lam, and veneer comply boards combining one to four wire net sheets were made from wood particle and sawdust with different spacings (8, 10, 12, and 18 Mok) and different wire diameters (0.35, 0.50, and 0.80mm) composing wire net. They were compared and analyzed statistically with specific gravity, thickness swelling, length swelling, bending properties (modulus of rupture, modulus of elasticity, work to proportional limit, and total work), internal bonding strength, and screw holding strength between wood particle and sawdust boards. The results obtained at this study as cording to the discussions might be concluded as follows; 1. In specific gravity, both particle and sawdust boards by press-lam method were higher than by conventional forming and veneer comply method, and the boards containing more wire net sheets also showed higher value. But the wire net spacings(Mok) had no influence on specific gravity. In general, particle board showed higher specific gravity than sawdust board. Veneer comply board showed lowest specific gravity values. 2. Both particle and sawdust boards by press-lam method was slightly lower than by conventional forming and veneer comply method in thickness swelling. The sawdust board containing 8, 12. and 18 Mok wire net showed lower thickness swelling than the corresponding particle board, but both sawdust and particle boards containing the T8 and 10 Mok wire net showed higher and similar thickness swelling. 3. Both particle and sawdust boards containing wire net showed no difference in MOR and MOE of bending. Comply board was the highest and particle board showed slightly higher than sawdust board in MOR and MOE values. 4. In work to proportional limit and total work in bending, both particle and sawdust boards containing thicker wire diameter and more wire net sheets showed higher value. From these facts, it is conceivable that boards with thicker wire diameter and more wire net sheets show increasing resistance against external force. But there was no significant difference between particle and sawdust borads. 5. In resistance against delamination (internal bonding strength), both sawdust and particle boards containing wire net showed lower value than control, and also showed decreasing tendency with more number of wire net sheet composed. Particle board showed higher resistance against delamination than sawdust board. 6. In screw holding strength, sawdust board containing thicker wire diameter and more wire net sheets showed higher value, but particle board by press-lam method was higher than by conventional forming and veneer comply method. Screw holding strength of particle board was higher than that of sawdust board.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.182-183
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• 2019

In this study, the optimization of mixing proportion of press-forming board with blast furnace slag, pearlite and bottom ash was investigated using the response surface methodology. Ten Mixing proportions of specimens were designed by the response surface design, and then flexural failure load, moisture content and water absorption of specimens were measured. As a result of the reaction surface analysis based on the experimental results, it was possible to derive the optimal mixing proportion with the satisfaction of 93%.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.74-84
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• 1995

Eight types of thin composite panels were manufactured by press-lam and mat-forming process applied to optimum manufacturing condition, studied in former first research by author (1995). They were tested and compared with control boards on dimensional stability, internal bond strength, tensile strength, Screw withdrawal strength, and bending properties. These thin composite panels manufactured by mat-forming process were generally superior to those by press-lam in dimensional stability and mechanical properties. In the dimensional stability and mechanical properties of thin composite panels manufactured by mat-forming process, the thin composite panels (A and E type) composed of particle or sawdust core and veneer face with polyethylene film, were as good as those of common plywood (control board). Internal bond strength showed highest value in the thin composite panel(D type) which composed of particle core and polypropylene screen face with polyethylene film. The thin composite panels(G and H type) composed of sawdust or particle core and polypropylene screen face with polyethylene film by press-lam and mat-forming process, showed most highest value in dimensional stability and water absorption.

• Journal of the Korean Wood Science and Technology
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• v.23 no.2
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• pp.55-69
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• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• Design & Manufacturing
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• v.14 no.3
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• pp.17-22
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• 2020

As devices such as smartphones, tablet PC, and wearable devices have been miniaturized, the connectors that go into the devices are also designed to be very small. The connector combines the plug and the receptacle to transfer electricity. As devices are miniaturized, the contact shape is formed by partially thinning the thickness of the raw material of the terminal in order to lower the coupling height of the plug and receptacle. The product used in this study is a receptacle terminal used for 0.4mm pitch board to board connector among fine pitch connectors. When the material thickness is reduced by forging the receptacle terminal, the width change of the pin is checked. To reduce the thickness of the material by forging, pre-notching is applied in the first step, forging in the second step, and notching in the third step. After forming the width dimension of the pin to 0.28 mm in the pre-notching process, in the forging process, the material thickness 0.08 mm and 0.02 mm (25%) were forged and the thickness was changed to 0.06 mm and the width change amount of the pin was measured. The facility produced 10,000 pieces at 400 SPM using a Yamada Dobby (MXM-40L) press, and thirty pins were measured and the average value was shown. After forging by using C5210-H (HP) and NKT322-EH, which are frequently used in connectors, analyze the amount of change in each material. The effect of punching oil on forging is investigated by appling FM-200M, which is highly viscous, and FL-212, fast drying oil. This study aims to minimize mold modification by predicting the amount of material change after forging.