Changes in materials technology

Since the technology of any age is founded upon the materials of the age, the era of new materials will have profound effect on engineering of the future.

Not only new materials, but related, and equally important, new and improved and less wasteful processes for the shaping, treating and finishing of both traditional and new materials are continuously being developed. It is important that an engineer should be familiar with them. These include casting, injection molding and rotational molding of components of ever increasing size, complexity and accuracy; manufacture of more complex components by powder metallurgy techniques; steel forming and casting processes based on new, larger and more mechanized machines, giving reduced waste and closer tolerances; the avoidance of waste in forging by the use of powder metallurgy or cast pressforms and new finishing processes for metals and plastics, just to name a few. A high proportion of these processes is aimed at the production of complex, accurate shapes with a much smaller number of operations and with far less waste than the traditional methods of metal manufacture.

Joining techniques have developed to unprecedented level of sophistication and are also providing opportunities for economies. It is necessary to mention that these newer techniques allow the manufacture of complicated parts by welding together simpler sub – units requiring little machining; such asasemblies can be made from a variety of materials. The methods can also be used effectively for assembly, allowing savings to be made in both materials and machine utilization.

Steel Mill Buildings

Adaptability of steel for industrial buildings. – Structural steel rightfully holds an important position among the materials that are adapted to use in the construction of industrial buildings. Its prime function is that of constituting the skeleton framework which supports the roof and side coverings together with any other parts or equipment that must be attached to or supported by it. Steel is noncombustible, strong, yet relatively light in weight for its strength; it is ductile, reliable, and generally available; it can be fabricated in advance to form members of the desired strength and dimensions, which can be erected quickly in the field where strong connections are easily made. Thus, steel is well suited to use in large plants having long spans, heavy loads, and large clear heights. It is also adapted to use in small structures.

As a material for the framework of industrial buildings, steel has two very important advantages:

Almost any structure within reason may be built of structural steel. This is a tremendous asset because of the great variety of shapes and sizes needed to house various industries.

A steel frame structure may often be remodeled or extended to suit changed conditions, new processes, and even completely new uses. Sometimes this is exceedingly advantageous. By the use of burning, welding, and riveting, extensive alterations may be made in the field prohibitive expense.

Another slight advantage, which may become important under special conditions, is the fact that the entire building may be dismantled and re – erected elsewhere when circumstances require it.

How can one tell whether to make a building out of steel or some other material? There may be simple but important matters that give the answer; e. g., personal preference, available materials, effect of weight on foundations if the soil is weak, suitability for the purpose, fire hazards, similarity to other buildings previously used and found to be satisfactory, similarity to adjacent buildings to be constructed, and speed and ease of construction. However, the required strength of the material and the relative economy may overrule these other factors when spans are long and loads are heavy.

The term “mill building” as used here denotes a single-story structure having one or more relatively wide aisles of considerable length and large clearance. The siding and roofing may be one or more of a wide variety of materials; generally, however, the whole construction is relatively light. Such a building generally houses large, heavy machinery supported directly on the ground; it may or may not have crane runways, trolley beams, or other overhead equipment for transporting materials. The manufacturing operations within it are usually those which require large areas on a single floor, and the handling of heavy or voluminous objects. Obviously, such buildings require long roof beams or trusses to span the aisles, slender but strong columns to carry heavy vertical loads, and substantial bracing to resist the wind forces against such large exposed wall areas. For all these, structural steel is admirably suited.

When planning the framework of a steel building, one should bear in mind the fact that commercial sections of steel are rolled in various sizes and shapes – but in these only. Unusual, complicated, and built-up members will naturally cost more per pound than will simple rolled sections without large fabrication cost. When special members are needed, however, they can be made up by riveting and welding, but they should be so planned that they can be composed of parts that in themselves are standard shapes.

The variety of shapes, sizes, and details of industrial structures is about as extensive as the needs for which each individual building is desired.

Unit 4

Welding

І. Language

Ex.1. Remember the following words and word combinations:

Welding to weld flame to melt to stick together arc welding resistance welding gas welding helmet goggles hot sparks weld to burn oxy-fuel welding electric welding shielded metal arc welding   gas metal arc welding   gas tungsten arc welding     welder rust grease oxygen evaporate argon helium carbon dioxide nitrogen hydrogen

зварювання, зварення зварювати полум’я плавитися з’єднуватися дугове зварювання контактне зварювання газове зварювання шолом захисні окуляри гарячі іскри зварювальний шов обпікати кисневе зварювання електричне зварювання дугове зварювання металевими електродами дугове газове зварювання металевими електродами дугове зварювання вольфрамовими електродами зварник, зварювання іржа змазування, змащення кисень випаровуватися аргон гелій вуглекислий газ азот вуглець

сварка сваривание пламя плавиться соединять дуговая сварка контактная сварка газовая сварка шлем защитные очки горячие искры сварной шов обжечь кислородная сварка электрическая сварка дуговая сварка металическими электродами дуговая газовая сварка металическими электродами дуговая сварка вольфрамовыми электродами сварщик ржавчина смазка кислород испарятся аргон гелий углекислый газ азот углерод

Ex. 2.Put these words according to the alphabet and translate:

Hurt, sunburn, electrode, protection, require, shield, flow, cool down, flame, special, bright, skin, instead, electrode, touché, might, flux, solid, paste.

Ex .3.Translate this sentences. Pay attention to the underlined words:

1. Use

- застосування - .використовувати

1. Today we use more than fifty welding processes. 2. Most of welding processes use heat to produce the welding joint. 3. What’s the use of increasing the temperature?

2. Reduce.

- зменшувати - зменшення

1. There is always a need to reduce manufacturing costs. 2. Reduction is the process by which oxygen is taken from another element.

3. Join.

- з’єднувати - приєднуватися

1. Welding is the process to join metals. 2. We can join you only at the end of this month. 3. Our young people join the army usually at the age of 18.

ІІ. Reading