Wooden pattern

Plaster molds from wooden patterns, up to 40 castings depending on mold... 

These metal patterns are more expensive than the wooden patterns used with green-sand casting and so, to be economic, the process requires larger numbers of castings - seldom less than 200. 

Well-arranged combustible storage, e.g., wooden patterns, noncombustible buildings Machine shop having noncombustible floors Temperature curve D (severe)... 

Wooden patterns glued with PVA adhesive. Fillets made with plastic wood. 

When rods are required they are placed in wooden trays in a formolising bath. If the requirement is for a disc or blank such as used by the button trade the extrudate is cut up by an automatic guillotine and the blanks are immersed in the formalin solution. For manufacture of sheets the rods are placed in moulds and pressed into sheets before formolising. Many attractive patterns may be made by pressing different coloured rods into grooves set on the bias to the rods, thus forming new multi-coloured rods. This operation may be repeated a number of times in order to produce complex patterns. 

The peak period for the use of aldrin and dieldrin was between the late 1960s and the early 1970s throughout various parts of the world (WHO, 1989). The use pattern of aldrin and dieldrin are quite similar. They act as effective contact and stomach poisons for insects. They are used to control soil insects (e.g. grasshoppers and corn rootworm), and protect crops and wooden structures from termites (WHO, 1989). The production of aldrin and dieldrin has decreased since the early 1960s. In the United States, the peak use of aldrin from 19 million pounds in 1966 decreased to 10.5 million pounds in 1970 (USEPA, 1980). During this same period (1966-1970), annual dieldrin use dropped from 1 million to 670,000 pounds. These decreases were primarily due to increased insect resistance to the aldrin and dieldrin, and to the development and availability of more effective and environmentally friendly pesticides (USEPA, 1980). 

Figure 15 shows the pattern made by the normal reflection of a detonation on a glass plate coated lightly with carbon soot, which may be from either a wooden match or a kerosene lamp. The cellular structure of the detonation front is quite evident. If a similarly soot-coated polished metal (or mylar) foil is inserted into a detonation tube, the passage of the detonation wave will leave a characteristic fish-scale pattern on the smoked foil. Figure 16 is a sequence of laser-Schlieren... 

A pretty pattern of revolving fire is obtained by turning a simple wooden wheel on which some fire dust spark compositions etc. are fixed and burnt. For driving the wheel turning cases are used as shown in F5.g.l28. 

Vat stills consist of cylindrical wooden vessels built of staves strongly hooped with wrought iron. They have high copper domes covering openings in the heads of the vessels which communicate with a retort or retorts of the Jamaica pattern, but, as a rule, the retort acts as the lowest vessel of a rectifying column. As in Winter s still a spiral pipe or a series of... 

There is considerable uncertainty as to when the harrow came into use but Fussell states that by the first century A. D. a harrow of some pattern was in existence. It was commonly made of wood fitted with either wooden or iron teeth. Various types of rakes, forks, spades and pickaxes were available for the preparation of the soil in gardens or rocky areas where the plow could not be used. A four-toothed fork or rake was used for the handling of manures, and pruning and grafting knives were also available. 

Residual stresses can also arise if a hole is drilled, with a blunt bit, through a product that is initially stress-free. The drilling operation generates enough heat to melt a thin annulus of plastic surrovmding the hole. When this cools down, it contracts, so has a residual tensile circiunferential stress (the effect is the converse of shrink-fitting a metal rim on a wooden wagon wheel). Consequently, cracks may start in a radial direction, but they will turn to follow the boundary of the overheated layer. These two examples show that the crack patterns can reveal the type of residual stress field in a product. 

On the moulding side, a basic distinction is made between permanent and lost moulds. Foundries casting in permanent moulds, buy these metal moulds (dies) externally, but typically operate an in-house mould repair and maintenance shop. Foundries casting in lost moulds, often buy wooden, metal or plastic patterns (for their mould design) and operate an in-house pattern maintenance and repair shop. Moulds, cores and lost models are generally produced as part of the foundry process. 

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