Metal Processing

One of the basic processes of the metal-working industry is the production of metal castings. A casting may be defined as “a metal object obtained by allowing molten metal to solidify in a mold”, the shape of the object being determined by the shape of the mold cavity. A foundry is a commercial establishment for producing castings.

Most castings serve as details or component parts of complex machines and products. In most cases they are used only when they are machined and finished to specified manufacturing tolerances providing easy and proper assembly of the product.

Forging is the oldest known metalworking process. It is believed to have begun when early man discovered he could beat pieces of ore into useful shapes. The blacksmith was one of the first to realize the advantages of forging. Although he did not know why, he knew that hammering a piece of hot metal not only resulted in a useable shape, it improved its strength.

To understand why forging improves the mechanical properties of metal, it is important to recognize that metal is made up of grains. Each grain is an individual crystal, and when the grains are large, cracks can occur and propagate along the grain boundaries. Therefore, it is desirable to minimize the grain size in a metal.

Reducing the metal’s grain size is one of the things that forging does so well. Forging breaks down a coarse-grained structure producing a chemically homogeneous wrought structure with much smaller grains by controlled plastic deformation. In forging, controlled plastic deformation results in greater metallurgical soundness and improved mechanical properties of the metal.

Metal shaping by controlled plastic deformation is the basis for all forging operations. Modern forging is not only carried out in virtually all metals, it is done at temperatures ranging from more than 2500^oF to room temperature.

Cutting is one of the oldest arts practiced in the stone age, but the cutting of metals was not found possible until the 18th century, and its detailed study started about a hundred years ago.

Now in every machine-shop you may find many machines for working metal parts, these cutting machines are generally called machine-tools and are extensively used in many branches of engineering. Fundamentally all machine-tools remove metal and can be divided into the following categories: 1. Turning machines (lathes); 2. Drilling machines; 3. Boring machines; 4. Milling machines; 5. Grinding machines.

Machining of large-volume production parts is best accomplished by screw machines. These machines can do turning, threading, facing, boring and many other operations. Bushings, bearings, nuts, bolts, studs, shafts and many other simple and complex shapes are among the thousands of products produced on screw machines. Screw machining is also used to finish shapes produced by other forming and shaping processes.

Language study

1. Find pairs of synonyms.

To define, to progress, nowadays, proper, parts, to produce, quick, details, to advance, to manufacture, rapid, to determine, suitable, at present.

2. Find pairs of antonyms.

Raw, simple, to feed, difficulty, complex, finished, ease, to retract.

3. Make nouns from the verbs.

To cast, to allow, to solidify, to determine, to establish, to tolerate, to discover, to recognize, to occur, to propagate, to forge, to cut.

4. Comment on the use of the tenses in the following sentences:

1. We’ll do that once you’ve made your final decision.

2. Charles can take the luggage to the apartment, after he's dropped us off.

3. Once the waiter has disappeared, we’ll discuss this problem.

4. As soon as you have seen her, come and tell me.

5. I’ll write to you after I have spoken to Frederick.

6. After Roger has written this book, he's having a holiday.

7. You can go when you've typed these letters.

8. I won't take any decision before I have received the fax from the head office.

5. Comment on the use of the Future Progressive.

1. Goodbye. You won't be seeing me for a long time.

2. Why must I take a book and a packed lunch? — You'll be sitting on the train for hours.

3. While you are slicing the cheese, I will be buttering the bread.

4. We'll be arriving at Miami airport at exactly this time tomorrow morning.

5. Next Sunday, the Prime Minister will be celebrating ten years in power.

6. Whenever I think of you, I will be remembering the shadow of your smile.

7. Will you be wearing your new earrings tonight?

6. Comment on the use of the Future Perfect.

1. By the time my parents get back home I will have cleaned the house from top to bottom.

2. The tourists hope that the tornado will have finished before they arrive in California.

3. Next month I will have known Rick for twenty years.

4. By the time you start writing your test I will have finished mine.

5. When you drop in at my place, I will have painted the door.

6. Will you have arranged everything by tomorrow?

7. Comment on the use of the Future Perfect Progressive.

1. Next year I will have been living in Moscow for thirty years.

2. Next month we shall have owned this house for ten years.

3. When he is forty, he will have been learning English for twenty five years.

4. By the time the manager turns up, the customers will have been waiting for him for several hours.

5. He complains that by May he will have been reading "War and Peace" for five months.

6. I shall have been staying here just a year this July.

8. Read the sentences and comment on the ways future actions can be expressed.

1. Their plane arrives at two o'clock in the morning.

2. I'm away on holiday next week.

3. The sun rises at 5.30 tomorrow.

4. She's making a speech at the conference next week.

5. I'm going to town next week.

6. I think it's going to rain.

7. Alison is going to enter the university this year.

8. This Saturday Nora will be celebrating her birthday.

9. He is to be in court tomorrow morning.

9. Use the verbs in brackets in the correct tense-form:

1. Prof. Smirnov (to give) a lecture on physics next week.

2. We (to have) the examination in 2 weeks.

3. We (to work) in the laboratory the day after tomorrow?

4. They (to make) a diagram at this time tomorrow.

5. Next year the plant (to produce) 1000 electric motors every day.

6. Tomorrow by 6 o’clock I (to report) the results of this analysis.

7. Our laboratory (to provide) with new equipment.

8. The problem (to discuss) at 5 p.m. tomorrow.

10. Translate into English.

1. Одним з основних процесів металообробної промисловості є виготовлення ливарних виробів.

2. Більшість ливарних виробів слугують деталями або комплектувальними складних машин.

3. Щоб зрозуміти, чому ковка покращує механічні властивості металу, важливо знати, що метал складається з гранул.

4. Формування металу за допомогою керованої пластичної деформації є основою всіх ковальських операцій.

5. Детальне дослідження різання металу почалося приблизно сто років тому.

Discussion

1. Are the following statements about the text true or false? Why?

1. A casting may be defined as “a metal object obtained by permitting molten metal to solidify in a mold”.

2. The shape of the object is not determined by the shape of the mold cavity.

3. The engineer was one of the first to realize the advantages of forging.

4. Forging improves the mechanical properties of metal.

5. It is not necessary to minimize the grain size in a metal.

6. In forging, controlled plastic deformation results in greater metallurgical soundness and improved mechanical properties of the metal.

7. Screw machines can do turning, threading, facing, boring and many other operations.

8. Screw machining cannot be used to finish shapes produced by other forming and shaping processes.