ТОР 5 статей:
Translate the sentences where predicate has the meaning of necessity.
1) Coarse sand is to be used for producing large castings.
2) Cores are used to make hollows in castings.
3) The molten metal is first poured into the ladles, then into molds.
4) The amount of water in molding sand should not be too much.
5) Castings with coarse surface are to be cleaned in final operation.
6) The process of casting metals has been known for many centures.
7) Certain alloys have been prepared to make the qualities of molten metal better.
8) In order to produce the castings with high quality we should pay much attention to the preparation of alloys.
Read and translate Text С
Materials which are used for sand molds are refractory silica sand, bonding materials and facing materials.
Bonding materials is a suitable binder which is usually a form of clay.
Molding sand is a mixture of silica sand, a suitable binder and water. Sometime two or more bonding materials are mixed with silica sand.
Molding sands require the following characteristics: they must be refractory to withstand the high temperature of molten metals, porous and must have sufficient bond.
silica – кварц, двуокись кремния
to bond – связывать, связывающее вещество, соединение
binder – связывающее вещество, крепитель, связь
sufficient – достаточный
facing – облицовочный песок, припыл