Which of the following methods are used to create freemachin

Which of the following methods are used to create free-machining metals (in order to reduce the friction generated during cutting)? (Select all that apply) Adding alloying agents that produce smaller cutting chips Adding alloying agents that increase the metal toughness Adding alloying agents that increase the metal ductility Adding alloying agents that serve as lubricants (such as lead)

Solution

OPTION C&D

=>Adding alloying agents that produce smaller chips. When the chips are small the get settledown on the work space. So this will restrict the free movement of the tool over the work piece and due to heat the chips may be attached to to the tool and give improper surface finish. So smaller chips are not suggeastable. so option A is wrong

=>Adding alloying agents that increase toughness. When toughness increases force requried to cut also increases thereby vibrations also increase and hence surface is not properly finished. So option B is wrong.

=>Adding alloying agents that increase ductility. Increasing ductility means the metal can be easily be reshaped so it can be finished smoothly. So friction decreases. So option C is correct.

=>Adding alloying agents that serves as lubricants. We know lubricants major purpose is to reduce friction.So option D is also Correct.