Engineering materials used to manufacture of articles or products, dictates which manufacturing process or processes are to be used to provide it the desired shape. Sometimes, it is possible to use more than one manufacturing processes, then the best possible process must be utilized in manufacture of product. It is therefore important to know what materials are available in the universe with it usual cost. What are the common characteristics of engineering materials such as physical, chemical, mechanical, thermal, optical, electrical, and mechanical? How they can be processed economically to get the desired product. The basic knowledge of engineering materials and their properties is of great significance for a design, manufacturing and industrial engineers. The elements of tools, machines and equipments should be made of such a material which has properties suitable for the conditions of operation. In addition to this, a product designer, tool designer and design engineer should always be familiar with various kinds of engineering materials, their properties and applications to meet the functional requirements of the design product. Product industrial engineers also need to have this knowledge. They must understand all the effects which the manufacturing processes and heat treatment have on the properties of the engineering materials.
CLASSIFICATION OF ENGINEERING MATERIALS
A large numbers of engineering materials exists in the universe such as metals and non metals (leather, rubber, asbestos, plastic, ceramics, organic polymers, composites and semiconductor). Leather is generally used for shoes, belt drives, packing, washers etc. It is highly flexible and can easily withstand against considerable wear under suitable conditions. Rubber is commonly employed as packing material, belt drive as an electric insulator. Asbestos is basically utilized for lagging round steam pipes and steam pipe and steam boilers because it is poor conductor of heat, so avoids loss of heat to the surroundings. Engineering materials may also be categorized into metals and alloys, ceramic materials, organic polymers, composites and semiconductors. The metal and alloys have tremendous applications for manufacturing the products required by the customers.
Metals and Alloys
Pure metals possess low strength and do not have the required properties. So, alloys are produced by melting or sintering two or more metals or metals and a non-metal, together. Alloys may consist of two more components. Metals and alloys are further classified into two major kind namely ferrous metals and non-ferrous metals.
(a) Ferrous metals are those which have the iron as their main constituent, such as pig iron, cast iron, wrought iron and steels.
( b ) Non-ferrous metals are those which have a metal other than iron as their main constituent, such as copper, aluminium, brass, bronze, tin, silver zinc, invar etc.
Ferrous metals are iron base metals which include all variety of pig iron, cast iron wrought iron and steels. The ferrous metals are those which have iron as their main constituents. The ferrous metals commonly used in engineering practice are cast iron, wrought iron, steel and alloy steels.
Main Types of Iron
1. Pig iron
2. Cast iron
(A) White cast iron
(B) Gray cast iron
(C) Malleable cast iron
(D) Ductile cast iron
(E) Meehanite cast iron
(F) Alloy cast iron
3. Wrought iron
4. Steel
(A) Plain carbon steels
1. Dead Carbon steels
2. Low Carbon steels
3. Medium Carbon steels
4. High Carbon steels
(B) Alloy steels
1. High speed steel
2. Stainless steel
Grey Cast Iron: Applications
The grey iron castings are mainly used for machine tool bodies, automotive cylinder
blocks, pipes and pipe fittings and agricultural implements. The other applications involved
are
(i) Machine tool structures such as bed, frames, column etc.
(ii) Household appliances etc.
(iii) Gas or water pipes for under ground purposes.
(iv) Man holes covers.
(v) Piston rings.
(vi) Rolling mill and general machinery parts.
(vii) Cylinder blocks and heads for I.C. engines.
(viii) Frames of electric motor.
(ix) Ingot mould
(x) General machinery parts.
(xi) Sanitary wares.
(xii) Tunnel segment.
White Cast Iron: Applications
(i) For producing malleable iron castings.
(ii) For manufacturing those component or parts which require a hard, and abrasion resistant surface such as rim of car.
(iii) Railway brake blocks.
Malleable cast iron
Malleable cast iron are generally used to form automobile parts, agriculture
implementation, hinges, door keys, spanners mountings of all sorts, seat wheels, cranks,
levers thin, waned components of sewing machines and textiles machine parts.
Wrought Iron: Applications
It is used for making chains, crane hooks, railway couplings, and water and steam pipes. It has application in the form of plates, sheets, bars, structural works, forging blooms and billets, rivets, and a wide range of tubular products including pipe, tubing and casing, electrical conduit, cold drawn tubing, nipples and welding fittings, bridge railings, blast plates, drainage lines and troughs, sewer outfall lines, weir plates, sludge tanks and lines, condenser tubes, unfired heat exchangers, acid and alkali process lines, skimmer bars, diesel exhaust and air brake piping, gas collection hoods, coal equipment, cooling tower and spray pond piping.
Aluminium: Applications
It is mainly used in aircraft and automobile parts where saving of weight is an advantage.
The high resistance to corrosion and its non-toxicity make it a useful metal for cooking
utensils under ordinary conditions. Aluminium metal of high purity has got high reflecting
power in the form of sheets and is, therefore, widely used for reflectors, mirrors and telescopes.
It is used in making furniture, doors and window components, rail road, trolley cars, automobile
bodies and pistons, electrical cables, rivets, kitchen utensils and collapsible tubes for pastes.
Aluminium foil is used as silver paper for food packing etc. In a finely divided flake form,
aluminium is employed as a pigment in paint. It is a cheap and very important non ferrous
metal used for making cooking utensils.
Copper: Applications
Copper is mainly used in making electric cables and wires for electric machinery, motor
winding, electric conducting appliances, and electroplating etc. It can be easily forged, casted,
rolled and drawn into wires. Copper in the form of tubes is used widely in heat transfer work
mechanical engineering field. It is used for household utensils. It is also used in production
of boilers, condensers, roofing etc. It is used for making useful alloys with tin, zinc, nickel
and aluminium. It is used to form alloys like brass, bronze and gun metal. Alloys of copper
are made by alloying it with zinc, tin, and lead and these find wide range of applications.
Brass, which is an alloy of copper and zinc, finds applications in utensils, household fittings,
decorative objects, etc. Bronze is an alloy of copper and tin and possesses very good corrosion
resistance. It is used in making valves and bearings. Brass and bronze can be machined at
high speeds to fine surface finish.
Red Brass: Applications
Red brass is mainly utilized for making, heat exchanger tubes, condenser, radiator cores,
plumbing pipes, sockets, hardware, etc.
Muntz metal: Applications
It is utilized for making for making tubes, automotive radiator cores, hardware fasteners, rivets, springs, plumber accessories and in tube manufacture.
Admiralty Brass: Applications
Admiralty brass is utilized for making condenser tubes in marine and other installations. It is used for making plates used for ship building. It is utilized also for making bolts, nuts, washers, condenser plant and ship fittings parts, etc.
Updated on 2 September 2019, 23 August 2019
