If you take admission to the Polytechnic after the completion of the ITI, then you can get admission to the course of Diploma directly in the 2nd year. If you have passed 10th or 12th and want to take admission in the Diploma course in Mechanical Engineering then you have to take admission in the 1st year.

To know more about Diploma in Mechanical Engineering, visit the link below:

https://www.careers360.com/courses/diploma-in-mechanical-engineering

I hope this answer helps. All the very best for your future endeavors!