Text a Founding

Founding is a process of producing metal objects, called castings. In this process molten metal is poured into a hollow mold, usually made of sand. The founding process itself is sometimes called casting. It is known that casting is a very ancient art being still used extensively. Although there are other methods of metal working, such as die-casting, forging and rolling, founding has not lost its significance.

Sand casting is one of the most popular and simplest types of casting that has been used for centuries. It involves three separate operations: first, a wood, plastic, or metal pattern intended as a replica of the finished object is made; then a hollow mold of sand is made; finally, molten metal is poured into the sand mold.

The pattern differs a little from the original, its dimensions being slightly enlarged to compensate for the shrinkage of the casting as it cools. Patterns can be made in one piece, but some castings are so complicated that it is easier to remove them from the mold if they consist of two or more parts.

The sand used in founding contains some amount of clay to make it more plastic when slightly moistened before use.

Sand is often used for molds because a certain amount of vapor and gas is assumed escaping the molten metal when it is poured in a sand mold. Having been used the sand mold is usually broken. But in manufacturing, to make two or more castings in a single mold is frequently desirable. Patterns of objects with overhanging parts may be made with removable pattern portions so that the pattern may be drawn from the mold piece by piece not breaking the sand mold.

For metals with low melting points, such as brass, it is possible to use solid molding materials. Such molds made of wood, plastic, cast iron, steel, aluminum, or other metal, have smoother surfaces than sand molds, and thus produce castings with finer detail and finish. They cannot, however, be used in the iron or steel casting.

Many variations and special techniques are involved in common founding. One of the comparably new casting methods is die casting. Its use supposes a fine surface quality and dimensional tolerance being achieved.

Die casting is the process in which molten metal is forced under high pressure into mold hollows (which are machined into dies). Most die castings are made from non-ferrous metals, specifically zink, copper, aluminium, magnesium, lead and tin based alloys, although ferrous metal die castings are possible. The die casting method is especially appropriate for applications where a large quantity of small to medium sized parts are needed with good high quality.

Whether the other new methods in founding will appear the future will show.

Задания к тексту A:

I. Прочитайте и переведите следующие выражения:

metal objects, called castings; molten metal; a hollow mold; mold hollows; the founding process itself; a very ancient art; metal working; die-casting, forging, extrusion, and rolling; sand casting; a sand mold; the most popular and simplest types of casting; a pattern intended as a replica; the shrinkage of the casting; some amount of clay; slightly moistened; a certain amount of vapor and gas; patterns of objects with overhanging parts; with removable pattern portions; piece by piece; metals with low melting points; solid molding materials; castings with finer detail and finish; one of the comparably new casting methods; a fine surface quality and dimensional tolerance; under high pressure; ferrous metals; non-ferrous metals; zink, copper, aluminium, magnesium, lead and tin based alloys; a large quantity of small to medium sized parts.

II. Найдите в предыдущем упражнении английские эквиваленты следующих русских выражений:

образец, предназначенный в качестве точной копии; литейный процесс сам по себе; металлы с низкой точкой плавления; самые популярные и простые типы литья; под высоким давлением; большое количество деталей с размерами от мелких до средних; образцы предметов с выступающими частями; литье в форму под давлением, ковка и прокатка; металлические предметы называемые отливками; отливки с более хорошей деталировкой и конечной доводкой; черные металлы; цветные металлы; расплавленный металл; обработка металла; со съемными частями образца; прекрасное качество поверхности и допуски по размерам; твердые материалы для форм; форма с пустотами; полости формы; некоторое количество глины; изделие за изделием; очень древнее искусство; сплавы на основе цинка, меди, алюминия, магния, свинца и олова; слегка увлажненный; некоторый объем пара и газа; литье в песчаную форму; один из сравнительно новых методов литья; песчаная форма; усадка отливки.

III. Прочитайте предложения, определите тип причастного оборота и правильно переведите предложения:

1. Its use supposes a fine surface quality and dimensional tolerance being achieved. 2. The pattern differs a little from the original, its dimensions being slightly enlarged to compensate for the shrinkage of the casting as it cools. 3. Sand is often used for molds because a certain amount of vapor and gas is assumed escaping the molten metal when it is poured in a sand mold.

IV. Определите тип придаточных предложений, сделайте грамматический разбор и переведите предложения:

1. Patterns can be made in one piece, but some castings are so complicated that it is easier to remove them from the mold when they consist of two or more parts. 2. Die casting is the process in which molten metal is forced under high pressure into mold hollows. 3. The die casting method is especially appropriate for applications where a large quantity of small to medium sized parts are needed with good high quality.

V. Ответьте письменно на следующие вопросы:

1. What is founding?

2. How is the founding process performed?

3. Is founding and casting the same?

4. What are the methods of metalworking?

5. Sand casting is one of the most popular and simplest types of casting, isn’t it?

6. What does it involves?

7. Does the pattern differs a little from the original and why?

8. How can patterns be made?

9. What sand is used for sand molds?

10. Is the sand mould usually broken after the first casting is poured?

11. What molding materials are used for metals with low melting points?

12. Is die casting a comparably new casting method or an old one?

13. How is the die casting process performed?

14. What are most die castings made from?

15. Whether will the other new methods in founding appear?

VI. Переведите текст А письменно.