1 Complete the table:
Materials
Technology
Processes
casting
Machine tools
milling
machines
grinding
machines
2 Complete the statement according to the text:
New materials will influence the new era of engineering …
because they can develop more advanced economy to solve many problems in industries.
because the technology is based on the materials of the age.
3 Answer the question:
Why is it so important to develop technology?
a) Technology is irreplaceable for solving contemporary environmental problems.
b) Technology improvement leads to the high level of production and consequently to the high standard of life.
c) Technology improvement gives reduced waste, closer tolerances, increases accuracy of treatment, provides opportunities for economies.
BUSINESS ACTIVITY
What type of document is in the box?
………………………………………………………………………………………. PROFESSIONAL TRAINING
………………………………………………………………………………………. |
a) Memo
b) Resume
c) Advertising Letter
d) Inquiry Letter
Text 2 Engineering Materials
Different metals are widely used in the machine-building industry. Metals applied for industrial purpose are called “engineering metals”. There are two groups of metals: ferrous and non-ferrous metals.
The example of ferrous metal is steel. Steel is an alloy of iron and carbon. Steel is strong and stiff, but corrodes easily through rusting although stainless and other special steels resist corrosion. There are three groups of steel: low-carbon, medium-carbon and high-carbon steels. Due to its advantages, steel has long been used and in great quantities in structural applications from bridges and buildings to ships, automobiles and household appliances. Steel is superior to other structural materials in strength, toughness, workability, and it is mass-produced with uniform, reliable quality and at low cost.
Cast iron is also a mixture of iron and carbon but with larger proportion of carbon than steel.
Non-ferrous metals are more expensive than ferrous metals and are used only when some characteristic not possessed by iron or steel is essential, desirable in application.
There are many non-ferrous metals such as copper, zinc, aluminium, nickel, lead, tin and gold.
Plastics are non-metallic, synthetic, carbon-based materials. They can be moulded, shaped, or extruded into flexible sheets, films or fibers. Plastics can be classified into several broad types.
Thermoplastics soften on heating, then harden again when cooled. Typical example of thermoplastics is polystyrene.
Thermosetting plastics do not soften when heated, and with strong heating they decompose. Thermosetting plastics have a higher density than thermoplastics. Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules to prevent stretching and creep.
Ceramics are often employed by engineers when materials which can withstand high temperatures are needed.