Chapter 4 Mechanical Engineering Materials 22343

Program: Diploma(Mechanical)
Class: SYME
Course: Mechanical Engineering Materials(22343)
Unit 04: Non ferrous Metals and Alloys
Lecture 09: Introduction to non ferrous metals & alloy of
Copper

1. Name of the Trainer :- Prof. S. B. Deshmukh
2. Years of Experience :- 8 Years
3. Domain Expertise :- Mechanical Engineering
www.sandipuniversity.edu.in
Presented By 02
https://www.sandipfoundation.org/
Department Of Mechanical Engineering,Sandip Polytechnic,Nashik

Unit – 4 Non ferrous Metals and Alloys 03
Topic to be covered
4.1 Copper and its alloys - brasses, bronzes Chemical compositions, properties and
Applications.
4.2 Aluminium alloys –Y-alloy, Hindalium, duralium with their composition and
Applications.
4.3 Bearing materials like white metals (Sn based), aluminium bronzes. Porous, Self
lubricating bearings.

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INTRODUCTION
Non-ferrous metals are those which do not contain significant quantity of iron or iron
as base metal.
These metals possess low strength at high temperatures, generally suffer from hot
shortness and have more shrinkage than ferrous metals.
Advantages of Non-ferrous metals
1. High corrosion resistance
2. Easy to fabricate, i.e., machining, casting, welding, forging and rolling
3. Possess very good thermal and electrical conductivity
4. Attractive color and low density
The various non-metals used in industry are:
copper, aluminium, tin, lead, zinc, and nickel, etc., and their alloys.

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INTRODUCTION
The arbitrary classification of non-ferrous metals:
1. Light metals: Aluminum, Magnesium, Titanium, Beryllium, etc.
2. Heavy metals: Copper, Zinc, Lead, Tin, etc.
3. Refractory metals: Tungsten, Nickel, Molybdenum, Chromium, etc.
4. Precious metals: Gold, Silver, Platinum, etc.
Aluminium (Al)
It is probably the most important non-ferrous metal.
It has outstanding physical properties (e.g. light weight, high thermal and electrical
conductivity, and corrosion resistance).
It is suitable for all machining, casting and forming operations.
This is silver in colour
Aluminum is the highest ranking material in use next to steel in case of
consumption/us

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Non-ferrous metals
Properties and Uses of Aluminium (Al)

7
Non-ferrous metals
Properties and Uses of Aluminium (Al)
1) Like copper it is also corrosion resistant.
2) It is very good conductor of heat and electricity although not as good a copper.
3) Possesses high ductility and light weight so widely utilized in aircraft industry.
4) Needs frequent annealing if cold worked since it becomes hard after cold working.
5) In view of its ductility and malleability it has replaced copper in electrical
transmission and appliances to some extent.
6) It is used in manufacturing of household utensils including pressure cookers.
7) It is used for aircraft bodies, drinks cans, high tension wires.

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Non-ferrous metals
Copper (Cu )

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Non-ferrous metals
Copper (Cu )
Properties and Uses of Copper (Cu )
1) High Thermal Conductivity : Used in heat exchangers, heating vessels and appliances,
etc.32 Manufacturing Processes
2) High Electrical Conductivity : Used as electrical conductor in various shapes and forms
for various applications.
3) Good Corrosion Resistance : Used for providing coating on steel prior to nickel and
chromium plating
4) High Ductility : Can be easily cold worked, folded and spun. Requires annealing after
cold working as it loses its ductility

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Non-ferrous metals
Lead (Pb)
Lead is a versatile material due to special properties of high atomic weight and
density, softness, ductility, low strength, low melting point, corrosion resistance and
ability to lubricate.
On the down side, toxicity is one of the chief disadvantages.
Solder is the alloy of lead and tin containing small amount of antimony and silver.
The solders are mainly used in soldering electronic circuits due to their lower melting
points.
Properties and Uses of Lead (Pb)
1) This is a very heavy metal; it is a dull grey colour and is flexible at room temperature.
2) It is resistant to corrosion and many chemicals do not react with it (even acids).

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Non-ferrous metals
3) It is soft, heavy and malleable, can be easily worked and shaped.
4) Lead is utilized as alloying element in producing solders and plumber's solders.
5) It is alloyed with brass as well as steel to improve their machinability.
6) It is utilized in manufacturing of water pipes, coating for electrical cables, acid tanks
and roof covering etc.

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Non-ferrous metals

13
Non-ferrous metals
Zinc (Zn)

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Non-ferrous metals
Zinc (Zn)
This is a grey colour.
It does not corrode easily and so it is used for galvanizing
(coating steel) to stop rusting and wood (in paint coatings).
Properties and Uses
1) High corrosion resistance: Widely used as protective coating on iron and steel.
2) High fluidity and low melting point: Most suitable metal for pressure die casting
generally in the form of alloy.
3) When rolled into sheets, zinc is utilized for roof
covering and for providing a damp proof non-corrosive
lining to containers.
4) The galvanized wires, nails, etc. are produced
by galvanizing technique and zinc is also
used in manufacture of brasses

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Non-ferrous metals
Tin (Sn)

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Non-ferrous metals
Tin (Sn)
As with many metals, pure tin is too weak to be used alone for most mechanical
applications
It is often alloyed with elements such as copper, antimony, lead, aluminum and zinc to
improve mechanical or physical properties.
It is commonly used as a coating for other metals such as tin cans, copper cooking
utensils.
Other applications include die-casting alloys,pewter chemicals, bronze, bearing alloys
and solder.

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Non-Ferrous Alloys
A nonferrous alloy consists of two or more materials, one of which must be a
nonferrous metal.
Nonferrous metals and nonferrous alloys are not based on iron and include metals and
alloys of aluminum, brass, bronze, copper, lead, tin, titanium, zinc, nickel, cobalt,
tungsten, molybdenum, magnesium, precious metals, refractory metals.
They are used in a variety of applications from construction to medical devices.
Many nonferrous metals can be used in alloys and are chosen for specific
characteristics such as strength, magnetic and electrical properties, and corrosion
resistance.
Other nonferrous metals and nonferrous alloys include copper beryllium, which is
used for electronic components, and beryllium oxide, which is used for its electrical
insulating properties.
Nonferrous metals and nonferrous alloys are have high density, and tensile strength.

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Copper and its Alloys
Copper was one of the first metals ever extracted and used by humans, and it has
made vital contributions to sustaining and improving society since the dawn of
civilization.
Copper was first used in coins and ornaments.
Copper tools helped civilization emerge from the Stone Age.
Copper and copper alloys are widely used in a variety of products that enable and
enhance our everyday lives.
Copper is one of the most useful metals known to man, and it was one of the first to
be utilized.
There are almost 400 different copper alloys depending on the commercial product
made.

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Copper

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Properties of copper
They have excellent electrical and thermal conductivities.
Color Copper is a reddish-yellow material.
It is extremely ductile and malleable.
It exhibit good strength and formability.
Copper has a Face-Centered Crystal (FCC) structure.
It has outstanding resistance to corrosion and fatigue
It has the second best electrical conductivity of the metals, second only to silver
compared to which it has a conductivity of 97 %.
The thermal conductivity of copper is very high falling in between silver and gold.
It is generally nonmagnetic.
It can be easily Fabricated, welded, brazed, soldered and machined.
They can be polished and buffed to almost any desired texture and luster.

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Uses of copper
Pure copper is used where required to pass electrical current like, Electrical wire and
cable, electrical contacts and various other parts.
Used extensively for automotive radiators, heat exchangers, home heating systems,
solar collectors, and various other applications requiring rapid conduction of heat across
or along a metal section.
It is used in heating pipes.
It is used in the form of rods, plates, sheets, strips, tubes, pipes.
It is also used for making foils and roofing.
It is used in electric heater, boiler tubes.
It is used in kitchen utensils.

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Copper Alloys
The excellent alloying properties of copper have made it invaluable when combined
with other metals, such as zinc (to form brass), tin (to form bronze), or nickel.
These alloys have desirable characteristics and, depending on their composition, are
developed for highly specialized applications.
For example, copper-nickel alloy is applied to the hulls of ships because it does not
corrode in seawater and reduces the adhesion of marine life, such as barnacles, thereby
reducing drag and increasing fuel efficiency.
Brass is more malleable and has better acoustic properties than pure copper or zinc
it is used in a variety of musical instruments, including trumpets, trombones, bells, and
cymbals.

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Copper Alloys
Copper Alloys are metal alloys that have copper as their principal component.
There are as many as 400 different copper and copper-alloy compositions
loosely grouped into the categories: copper, highcopper alloy, brasses, bronzes, copper
nickels,copper-nickel-zinc (nickel silver), leaded copper, and
special alloys.

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fig. shows
the
classification
of
Copper
alloys

25
Summary
In this lesson, We have learned
Introduction of Non ferrous metal
Non ferrous metal Properties and uses
Properties and uses of Copper
Classification of Copper

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Class: SYME
Lecture 10: Brass, Bronze and Gunmetal- Uses & Properties

Topic to be covered
•brasses, bronzes Chemical compositions, properties and Applications.
•Gunmetal Chemical compositions, properties and Applications.

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Brass (Copper-Zinc)
Brass is a metallic alloy that is made of copper and zinc.
The proportions of zinc and copper can vary to create different types of brass alloys
with varying mechanical and electrical properties.
It is a substitution alloy : (atoms of the two constituents may replace each other within
the same crystal structure).
It is classified into two main groups viz,
i) Alpha brass (Zinc < 30%)
ii) Alpha -Beta brass (Zinc = 30 to 44 %)
Properties of Brass
It is a Golden colored alloy.
It has good corrosion resistance.
It has high ductile strength.
It has high tensile strength.
It is hard and brittle material.

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Brass (Copper-Zinc)
What Is Brass?
Brass is a metal alloy primarily
composed of copper and zinc.
However, other metals—such as
iron, aluminum, silicon, and
manganese—are also mixed in to
produce different properties and
color variations. For instance, a high
zinc content leads to increased
strength and ductility, while the
inclusion of manganese results in
enhanced corrosion resistance.

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Brass (Copper-Zinc)
Uses of Brass
Brass is used for decoration for its bright gold-like appearance.
Used for applications where low friction is required such as locks, gears, bearings,
doorknobs, ammunition casings and valves.
Used for plumbing and electrical applications.
It is extensively in brass musical instruments
such as horns and bells.
It is also used in zippers.
Brass is often used in situations in which it is important
that sparks not be struck, such as in fittings
and tools used near flammable or explosive materials.
It is used to make hinges, screws, outside taps.
It is often used as decoration and for coins.
In antiquity, polished brass was often used as a mirror.

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Brass (Copper-Zinc)
Brass Types
Cartridge brass (70:30 brass)
Chemical composition :- Copper 70 % and Zinc30 %
Properties of Cartridge Brass :-
It has high ductility and malleability.
It has good cold working properties.
It has good corrosion resistance.
It is soft material.
Good hot formability.
Uses of Cartridge Brass
Plumbing accessories,Fasteners,radiatorcores,radiator fins and tanks
It is used for cartridge cases.
It is used for ammunition cases.
It is used for springs.

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Brass (Copper-Zinc)
Admiralty Brass (71:28:1 Brass )
Chemical composition :- Copper 71 %, Zinc 28 % and Tin 1 %
Properties of Admiralty Brass :-
It has high ductility and malleability.
It has good cold working properties.( Ease of blending & joining)
It has better corrosion resistance due to addition of tin (Tin).
They are easy for blending & joining.
They are light in weight.
Uses of Admiralty Brass :-
It is used for condenser tubes.
It is used in heat exchangers.
It is used in marine applications.
It is used in ship-building, power plants, desalinations plants etc.

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Brass (Copper-Zinc)
Muntz Metal (60:40 Brass)
Chemical composition :- alpha-beta brass with about 60% copper, 40% zinc
and a trace of iron
It is named after George Muntz, a metal-roller of, England, who commercialized the
alloy .
Also known as alpha-beta brass, Muntz metal, yellow metal, 60:40brass.
Its original application was as a replacement for copper sheathing placed on the
bottom of boats, as it maintained the anti-fouling abilities of the pure copper.
As it cost around two thirds of the price of pure copper and had identical properties for
this application.
Properties of Muntz Metal
It has high strength and hot machinability.
It is reddish in color.
It has tensile strength 350 to 400 MPa.

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Brass (Copper-Zinc)
Properties of Muntz Metal
It has good resistance to corrosion.
It has good conductor of heat.
Uses of Muntz Metal
It is used for utensils.
It is used for bolts, pump parts, condenser tubes etc.
It is used for making marine fittings, condenser heads, radiator cores, springs, chains
etc.
It is used in making castings and hot-worked products.
It is used as a lining on boats.

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Brass (Copper-Zinc)
Naval Brass (60:39:1 Brass)
Chemical composition :- 60%Copper, 39% zinc and 1% tin.
Naval brass is the classic marine, high-strength and corrosion-resistant alloy.
Properties of Naval brass
It has excellent corrosion resistance.
Good working qualities.
It has high tensile strength.
It has better hardness.
Uses of Naval brass
It is widely used in marine construction where strong, corrosive-resistant and hard
material is required
It is mainly used for marine hardware, hence called as naval brass
It is suitable for both salt and fresh water applications
It is used for welding rods and piston rods.

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Brass (Copper-Zinc)
Uses of Naval brass
It is used for propeller shaft, valve stem, pump
impellers, nuts, bolts etc.
It is used for heat exchanger tubes, aircraft turn buckle
barrels, dies, and many more.
Red Brass
Red brass can be considered both a brass and a bronze.
It typically contains 85 % copper, 5 % tin, 5 % lead, and
5 % zinc.
It is used to produce pipes, valves, and plumbing
fixtures, and is considered to
offer a good mixture of corrosion resistance, strength,
and ease of casting.

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Bronze (Copper -Tin)
The word bronze is borrowed from Italian word "bronzo” means bell metal, brass"
Bronze is an alloy consisting primarily of copper, commonly with about 12 % tin and often
with the addition of other metals (such as aluminium, manganese, nickel or zinc).
These additions produce a range of alloys that may be harder than copper alone, or
have other useful properties, such as stiffness, ductility, or machinability.
It is a dark Green colour and is easily cast making it ideal for statues.
Main bronze types are Al-Bronze, Tin-Bronze, Be-Bronze, Si-Bronze.
Properties of Bronze
Bronze is considerably less brittle than iron.
They are generally about 10 percent heavier than steel.
Bronze resists corrosion (especially sea water corrosion).
Bronze resists metal fatigue more than steel.
It is also a better conductor of heat and electricity.

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Properties of Bronze
The melting point of Bronze is about 950 °C.
It has good bearing properties
Uses of Bronze
Bronze is commonly used in ship propellers and submerged bearings due to its
combination of toughness and resistance to salt water corrosion.
It is also widely used for cast bronze sculpture.
Bronze parts are tough and typically used for bearings, clips, electrical connectors and
springs.
It is still widely used today for springs, bearings, bushings, automobile transmission
pilot bearings.
It is particularly common in the bearings of small electric motors.
It is also used in guitar and piano strings.
It is also used for making statues.

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Uses of Bronze
Bronze is the most popular metal for top-quality bells, particularly bell metal, which is
about 23 % tin.
Bronze has been used in the manufacture of various types of medals for centuries.

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Applications of Bronze
Bronze’s characteristics make it suitable for use in functional and aesthetic applications,
such as:
•Marine and fishing. Many boats and ships employ bronze fittings and propellers due to
the material’s high corrosion resistance.
•Sculptures and musical instruments. Bronze’s dull-gold tone makes it a popular source
material for sculptures and other artistic endeavors, such as bells and cymbals.
•Electrical connectors and springs. Some bronze alloys are particularly suitable for
electrical applications due to their excellent electrical conductivity.
•Bushings and bearings. The material’s low metal-to-metal friction makes it suitable for
high-stress environments, such as those experienced by bushings and bearings.

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Phosphor Bronze
Chemical composition of Phosphor bronze It is an alloy of copper with 3.5 to 10% of tin
and a significant phosphorus content of up to 1%.
The phosphorus is added as deoxidizing agent during melting
Properties of Phosphor bronze
It has good toughness and strength.
It has low coefficient of friction and fine grain.
The phosphorus also improves the fluidity of the molten metal and thereby improves
the castability.
It has good chemical resistance.
It has good fatigue and wear resistance.
Uses of Phosphor bronze
It is used for making springs, bolts for marine environment.
The alloy is also used in some dental bridges.

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Uses of Phosphor bronze
It is used for pipe fittings.
It is used for gears.
It is used for bearings.
It is used in some metal wind instruments

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Brass Vs Bronze
Bronze Brass
Harder, more brittle Greater malleability
Melting point of 950
degrees Celsius
Melting point of 900
degrees Celsius
Excellent corrosion
resistance (incl. saltwater)
Good corrosion resistance
Suitable for some
decorative applications
(e.g., sculptures, musical
instruments, etc.)
More suited for decorative
applications
(due to gold color)
Dates back to 3500 BCE Dates back to 500 BCE

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Gunmetal
Alloys of copper with tin, zinc and lead have been used for at least 2000 years due to
their ease of casting and good strength and corrosion resistance.
Early uses were for brooches, mirror cases, church doors, fonts and statues.
Originally used mainly for making guns.
Its use is now obsolete with the manufacture of steel ordnance.
Chemical composition of Gunmetal :- It has 88 % Copper, 10 % Tin and 2 % Zinc. Zinc is
added to clean the metal and to increase fluidity.
Properties of Gunmetal
It contains lead in addition to the zinc.
It is easy to casting and machining.
It has a tensile strength of 221 to 310 MPa, a specific gravity of 8.7, a density 8,719
kg/m3, and a Brinell hardness of 65 to 74 BHN.
It is resistant to corrosion from steam and salt water.

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Gunmetal
Uses
It is used to make steam and hydraulic castings, valves, and various small objects, e.g.
buttons.
They are also frequently used for bearings where loads and speeds are moderate.
Gun metals are the first choice for modern statues.
It is used for manufacturing gears.
It is used for manufacturing bushes, nuts etc.

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Gunmetal

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Summary
Bronze – Properties, uses
Brass - Properties, uses
Gunmetal - Properties, uses

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Class: SYME
Lecture 11: Introduction to non ferrous metals & alloy of
Copper

Topic to be covered
•Aluminium alloys –Y-alloy, Hindalium, duralium with their composition and
Applications.
•Bearing materials like white metals (Sn based), aluminium bronzes. Porous, Self
lubricating bearings.

54
Aluminum and its Alloys
Aluminum is a one of the most widely used non ferrous metal.
Properties of Aluminum
Aluminum is a silverish white metal
It has a strong resistance to corrosion.
It is malleable and ductile.
It is a relatively light metal compared to metals such as steel, nickel, brass, and copper.
It is non magnetic and non sparking.
Aluminum is easily machinable.
It also has good electrical and thermal conductivities.
It highly reflective to heat and light.
Aluminum is a very versatile metal and can be cast in any form known.
It can be rolled, stamped, drawn, spun, roll-formed, hammered and forged.
Aluminum can riveted, welded, brazed, or resin bonded.

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Uses of Aluminum
Aluminium is used for utensils, combs, collar buttons, flower pots etc.
It is mainly used for electrical wires.
It is used for food containers.
It is used for chemical storage equipments.
It is used for structural frames of light load.

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Aluminum Alloys :- These are designated by LM (Light Metal) series.
Y Alloy
Y alloy is a nickel-containing aluminium alloy.
It was developed by the National Physical Laboratory during World War 1, in attempt to
find an aluminium alloy that would retain its strength at high temperatures.
This addition of nickel was an innovation for aluminium alloys.
These alloys are one of the three main groups of high-strength aluminium alloys, the
nickel-aluminium alloys having the advantage of retaining strength at high temperatures.
Chemical composition of Y Alloy
Copper 4 %, Nickel 2 %, Magnesium 1.5 % and
remainder is Aluminium

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Properties of Y Alloy
It retains its strength at high temperatures.
It has a strong resistance to corrosion.
It can be easily cast.
It has good mechanical and shock absorbing properties.
It has low thermal expansion.
Uses of Y Alloy
It is mainly used in IC engine for piston and cylinder head.
It is used for casting and forging purpose.
AL1091 Yttrium-Aluminum Alloy (Y-Al Alloy)

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Duralumin
Duralumin is also called duraluminum, or dural.
The main alloying constituents are copper, manganese, and magnesium.
Chemical composition of Duralumin
A commonly used modern equivalent of this alloy type is AA2024, which
contains 4.4 % Copper, 1.5 % magnesium, 0.6 % manganese and 93.5 % aluminium
by weight.
Properties of Duralumin
Duralumin alloys are relatively soft, ductile.
It is workable in the normal state.
They may be rolled, forged, extruded, or drawn into a variety of shapes and products.
Their light weight and consequent high strength per unit weight compared to steel suit
them for aircraft construction

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Properties of Duralumin
Duralumin also is popular for use in precision tools such as levels because of its light
weight and strength.
The addition of copper improves strength, but it also makes these alloys susceptible to
corrosion.
Uses of Duralumin
It is used for applications where good machinability and good strength are required.
It is used in Aircraft structures, rivets, hardware, truck wheels, screw machine products,
and other miscellaneous structural applications.
It is used for sheet for auto body panels.
It is used for die and hand forgings.
It is used for pistons and rotating aircraft engine parts for operation at elevated
temperatures.

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Hindalium
It is an alloy of aluminium and magnesium with a small quantity of chromium.
It is manufactured as rolled product in 16 gauge mainly used in manufacture of
anodized utensils.
It is the trade name of aluminium alloy produced by Hindustan Aluminium Corporation
Ltd, Renukoot (U.P.).
Uses of Duralumin

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Bearing Materials

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Bearing Materials

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Bearing Materials
Bearing is a member designed to support a load while permitting relative motion
between two elements of a machine.
Metallic surfaces sliding together under load have a tendency to adhere causing
tearing or scoring of surfaces, heat generation results and finally seizure.
This factor is of primary importance in all bearing design.
To counter this problem the designer aim is to use materials with suitable lubricants to
minimize this effect.
Characteristics of Bearing Materials
It must be strong enough to carry the load – high compressive strength.
It must have high fatigue strength - durable.
It must have low friction.
It should have high thermal conductivity to remove friction heat from the surface.

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Bearing Materials
Characteristics of Bearing Materials
It should have the ability to absorb and discard small contaminant particles to keep
them from scoring the shaft.
It should be capable of slight adjustments to compensate for shaft roughness and
misalignment this is the ability of the bearing to "wear-in".
It must be corrosion resistant.
It must be relatively easy to machine or form to shape-reasonable cost.
It should be compatible to lubricant used e.g. should not corrode if water is used.
The bearing should be tolerant to dirt and foreign matter.

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Bearing Alloys
White metals or Babbitt Metals.
Babbitt, also called Babbitt metal or bearing metal, is any of several alloys used for the
bearing surface in a plain bearing
The original Babbitt metal was invented in 1839 by Isaac Babbitt, USA.
Chemical composition of Babbitt Metals :-
"90 % tin, 10 % copper
"80 % lead, 15 % antimony, 5 % tin
"76 % copper, 24 % lead
"75 % lead, 10 % tin
"67 % copper, 28 % tin, 5 % lead
Properties of Babbitt Metals
It has good hardness.
It has good ductility.
Babbitt metal is characterized by its resistance to galling.

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Bearing Alloys
Properties of Babbitt Metals
It has good hardness.
It has good ductility.
Babbitt metal is characterized by its resistance to galling.
Babbitt metal is soft and easily damaged, which unsuitable for a bearing surface.
Its structure is made up of small hard crystals dispersed in a softer metal, which
makes it a metal matrix composite.
As the bearing wears, the softer metal erodes somewhat, which creates paths for
lubricant between the hard high spots that provide the actual bearing surface.
When tin is used as the softer metal, friction causes the tin to melt and function as a
lubricant, which protects the bearing from wear when other lubricants are absent.

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Bearing Alloys
Uses of Babbitt Metals
It is used in light and medium IC engine big end bearings.
It is used for general purpose heavy bearings.
It is used in heavy duty marine engine bearings, electrical machines.
It is used in low cost, general purpose, medium duty bearings.

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Bearing Alloys
Copper-Lead Alloy
Chemical composition :- 20-40 % Pb,60-80 % Copper and small amount of Tin
An alloy containing copper and lead, which has the poorest weldability because the
toxic lead often contaminates the weld.
Hardness of lead based overlay materials is in the range 8-20 HV depending on the
content of the hardening component.
Fatigue strength of the lead based overlays is about (50-70 MPa)
Lead is toxic in nature, so in many applications the alloys containing toxic lead are
replaced with new developed lead-free materials.
It has excellent soft anti-friction properties.
Their relatively low fatigue strength limiting their applications in highly loaded engines.
It is generally used in automotive and aerospace applications.
It is used for making batteries and also for roofing.

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Bearing Alloys
Leaded Bronze
Chemical composition :- 4 to 6% tin, lead, zinc and 84-86 % copper
It has good machinability.
It has good strength, maximum load capacity, fatigue resistance, and hardness .
Zinc is sometimes used as a replacement for tin, and nickel (or nickel or silver) is often
added to improve corrosion resistance and toughness.
Leaded bronzes have better compatibility than tin bronze.
It has good antiscoring properties with soft shafts.
They are used in machine tools, farm machinery, and pumps.
It is also used in lathes, instruments, household appliances, diesel rocker-arm bushings,
automotive piston-pin bushings, and trunnion bearings.
It is widely used for diesel engine bearings, in cranes, and in railway and earthmoving
equipment.
It is also used in bolts, nuts, and for ball point pen etc.

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Bearing Alloys
Aluminum Bronze
It is an alloy of copper and aluminum.
The aluminum bronze with 6-8 % aluminum has valuable cold working properties.
The 6 % aluminum alloy has a fine gold colour which is used for imitation jewellery and
decorative purposes.

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Bearing Alloys
Porous and Self-lubricating Bearing
Most porous-metal bearings consist of either bronze
or iron which has interconnecting pores.
These voids take up to 10 to 35% of the total volume.
In operation, lubricating oil is stored in these voids and feeds through the
interconnected pores to the bearing surface.
Any oil which is forced from the loaded zone of the bearing is reabsorbed by capillary
action.
Because these bearings can operate for long periods without additional lubricant, they
can be used in inaccessible or inconvenient places where relubrication would be difficult.
Adding from 1 to 3.5 % graphite frequently enhances self-lubricating properties
The oil contained in the porosity provides a constant lubrication between bearing and
shaft, so the system does not need any additional external lubricant

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Bearing Alloys
Self-lubrication resulting in a very low friction coefficient.
Advantages of Self-lubricating sintered bearings
1. Reliability : The constant oil presence eliminates the risk of seizure, and allows the
bearing to work during thousands of hours without wear.
2. Economy : Maintenance-free, no need for lubricants.
Working :-
a. When the journal in an oil-impregnated self-lubricating bearing starts to turn, friction
develops, the temperature rises, and oil is drawn out of the press because of the
greater coefficient of expansion of the oil compared with the metal and because of
the hydrodynamic pressure differential in the oil film between the journal and the
bearing.
b. When rotation stops and the bearing cools, the oil is reabsorbed by capillary action.

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Bearing Alloys
Examples of powder metallurgy bearings
Automotive : Heater motors, window lift motors, air conditioners, windshield wiper
motors, power antenna motors, trunk-closing motors, seat adjuster motors.
Portable power tools : Drills, reciprocating saws, jigsaws, and sanders .
Home appliances : Washers, dryers, refrigerators, blenders, mixers, food processors, fans
and clocks.
Consumer electronics : Phonographs, high-fidelity equipment, stereo equipment, tape
players, and video recorders.
Business machines : Typewriters, computers, and copiers.
Farm and lawn equipment : Tractors, combines, cotton pickers, lawn mowers, string
cutters, and chain saws.

74
Bearing Alloys
Examples of powder metallurgy bearings

75
Summary
Alloy of aluminium
Bearing Materials
Self lubricating bearing

76

Chapter 4 Mechanical Engineering Materials 22343

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Chapter 4 Mechanical Engineering Materials 22343