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

100 Introduction to Basic Manufacturing Processes and Workshop Technology
melting, vacuum or inert gas is necessary because it is very reactive and forms compounds
with the furnace atmosphere and refractory materials. In order to fabricate components from
beryllium, powder metallurgy techniques are used.
5.16.6. Niobium
Niobium possesses good corrosion resistance, strength and ductility. It has a high melting
point of 2470°C. Its oxidation resistance above 400°C is indifferent, but can be greatly improved
by alloying elements. It is added to many base metals to produce heat resisting alloys but this
material is quite expensive.
5.17 MATERIAL SELECTION PROCEDURE FOR COMPONENTS
For selection a material for a particular application, one has to take into consideration
various physical and mechanical properties of the material. Selection of material for a
manufacturing process is an important decision. In many instances, the selection of a specific
material can even dictate the manufacturing process to be used. The selection of material also
has an influence on the final cost of the product. It is important to note that the material
cost accounts to approximately 50% of the manufacturing cost. Hence, selection of manufacturing
process for a material must be made with the due care. The stepwise approach for material
selection is as follows:
1 Initially material requirement is identified by keeping in view overall objectives of
the part for which the selection of material is made. These objectives can be
referred with reference to cost, durability, life, etc.
2 The material requirements are identified through a number of materials. For example,
low specific weight requirement is met by aluminium and also by nylon. Make a list
of all such materials that meet all or most of the, requirements.
3 In case when more than one material appears to be suitable, the final choice should
be determined by considering influencing factors and restrictions like availability of
raw material, cost, inhibitions of aesthetics, and so on. For example, when we want
to select a material for manufacturing coins, the requirements are: the material
should possess good ductility, hardness, corrosion resistance, high plasticity, and
should be light in weight. The list of materials that satisfy these requirements is
large including gold, silver, copper, and their alloys. Final selection may be made
taking into consideration cost and availability. As another example, one uses stainless
steel for manufacturing shaving razor blades because the material selected should
have good malleability (ability to be hammered into thin sheets), corrosion resistance,
more abrasive resistance, and economical. The edge may be alloyed to make it hard
and retain sharpness.
The material selection procedure for the following products is given as under.
Rock crusher jaw
The function of crusher jaws is to crush. The crusher jaws should be hard, shock
absorbing and require good compressive strength. For such properties we choose cast-iron
because it has good castability, fluidity and good damping capacity. Its castings are made by
dry sand casting process.