Question

As per the Indian standards, the limits and fits specify how many grades of tolerances?

• A. 10
• B. 18
• C. 22
• D. 28

Hint:

Remember the standard classification system values: - Number of standard tolerance grades = 18 - Number of fundamental deviations = 25 (extended to 28 in newer standards, but fundamental categories remain distinct).

Answer 1

The Correct Option is B

The IT grade system starts from the very finest grade and runs down to the coarsest. Counting them out, IT01 and IT0 are the two super fine grades used for master gauges, and then IT1 right through IT16 gives sixteen more grades covering everything from precision fits down to rough casting work. Adding these together, 2 plus 16, gives a total of 18 standard tolerance grades defined under the Indian Standard system, matching the ISO scheme it is based on.