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КАТЕГОРИИ:






Guess what adjectives were these nouns derived from. Write down and translate these nouns.




 

simplicity, similarity, difficulty

 

3. Translate the nouns derived from the verbs with the help od prefix ‘dis‘.

Note!Приставка dis- придаёт слову отрицательное или противоположное значение

 

to believe – верить to charge – нагружать to cover – покрывать to join – соединять disbelieve – … discharge – … discover – … disjoin – …

 

4. Read the title. What do u think this text is about? Read the text and check your answers. Translate the text.

Text A

METAL MOLDING

One of the most important operations in foundry is molding. There are sand and metal molds. Metal molds are also called permanent molds.

Metal molds consist usually of two hollow parts which should be joined for pouring metal into the mold. The inside of the metal mold is covered with carbon or graphite in order that the castings could not stick to the mold.

When the metal in the mold has solidified, these hollow parts are disjoined and the casting is removed. If necessary, cores constructed of metal or sand are employed to form hollows in the castings.

Castings are produced in permanent molds from non-ferrous metals and their alloys. These castings are strong and better finish surface and structure.

Metals used to make permanent molds must withstand high temperature and may be steel, iron, bronze or other suitable metal, depending on the melting point of cast metal. Bronze molds are employed sometimes for casting metals and alloys of very low melting temperature.

Metal molds are generally used to make many castings from one mold. There are practical for large production of small and medium-size castings of simple shape. However, the use of metal molds is limited because of some difficulties. Large castings are difficult to produce in permanent molds. Metal molds are of the higher cost than sand molds.

 

5. Explain the difference between «metal mold» and «permanent mold». Find the proof in Text A.

 




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