Introduction to Basic Manufacturing Processes and ... - always yours

90 Introduction to Basic Manufacturing Processes and Workshop Technology
furnace to get commercially pure tin. Chemically pure tin is made by electrolytic deposition
from commercial tin.
Properties
Tin is considered as a soft and ductile material. It possesses very good malleability. Its
melting point is 232°C and specific gravity is 7.3. It is malleable and hence can be hammered
into thin foils
Applications
Tin-base white metals are commonly used to make bearings that are subjected to high
pressure and load. Tin is used as coating on other metals and alloys owing to its resistance
to corrosion. It is employed in low melting point alloys as a substitute for Bismuth. It is
generally preferred as moisture proof packing material. Because of its high malleability, it
finds application in tin cans for storing food and food items.
5.7.1 Tin Base Alloy
Tin base alloy is also known as Babbitt metal which contains
Sn = 88%
Sb = 8%
Cu = 4%
Properties
Babbit metal possesses excellent antifriction properties and sufficient mechanical strength.
It can be easily casted. It is expensive because of high tin content.
Applications
Because of the above properties, Babbit metal is the most common bearing metal used
with cast iron boxes where the bearings are subjected to high pressure and load applications.
5.8. BEARING OR ANTIFRICTION ALLOYS
A bearing alloy or antifriction alloy commonly possesses good wearing quality, low co-efficient
of friction, high thermal conductivity, good casting qualities, non-corrosive properties, ability
to withstand high pressure and impact, low shrinkage after coating and less cost. Various
Bearing Metals are:
5.8.1 Admiralty Gun Metal
The composition of admiralty gun metal generally contains
Cu = 88%
Sn = 10%
Pb = 2%
Properties
Admiralty gun metal is having tensile strength of the order of 270 MN/m 2 . It possesses
elongation of about 20% and Brinell Hardness of 65 BHN.