Tolerance plays a crucial role in the manufacturing of mechanical parts. It defines the acceptable variation in dimensions, shapes, and positions.

Accurate tolerancing is essential to ensure proper fit and functionality of components within an assembly. A too-tight tolerance can increase production costs, while a too-loose one may lead to performance issues or premature failure.

For example, in a gear system, the tolerance of the shaft and gear diameters must be precise to avoid excessive play or binding. Similarly, in a piston-cylinder assembly, the clearance between the piston and cylinder walls needs to be within the specified tolerance range for optimal engine performance.

Manufacturers determine tolerances based on factors like the part's function, manufacturing processes, and cost considerations. Meeting these tolerance requirements is vital for the quality and reliability of mechanical systems.