Production

This is the most important subject and you need to study this whole heartedly. One of the biggest misconception is that it is theory subject but I must reveal you the truth that it is a numerical subject, you talk about casting, machining or metrology all have numerical. For those who are starting I must advice that leave theory part just focus on numericals. Once you get little experience just see theory of those question which come in objective problems of GATE, thats all no more theory. Notes are good, content in books are scattered and it would take lot time to sort it out. Although machining, metrology and casting are very well given in PC Sharma book, you may refer to them you wont regret.
Now talking about Engineering materials, well from this subject at max 1 question will be asked so I recommend to study only the basics like unit cell, miller indices and defects, these things we have been studying from our school days. Don’t put extra effort in material science.

Previous Year Solution?

You should practice previous year question with utmost importance and attention. Click here for previous year GATE question

Which book to refer?

Its always preferred to read book that you have already studied during your BTech. In case you didn’t read any book like most of the engineers.
Following are the books that i would recommend-

Book Name Links
Product Details Production Technology By PC Sharma Flipkart

Amazon

Product Details

Manufacturing Engineering and Technology By Kalpakjian

Amazon

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