What is meant by "tolerance" in engineering design?

In engineering design, "tolerance" refers specifically to the permissible limit of variation in a physical dimension. This concept is critical because it defines the acceptable range within which a particular dimension can deviate from its nominal or intended value while still ensuring that the parts will function properly when assembled.

Tolerances are established to accommodate factors such as manufacturing processes, material properties, and thermal effects. For instance, if a part is designed to be 10 mm in diameter with a tolerance of ±0.1 mm, it can be safely manufactured to dimensions anywhere between 9.9 mm and 10.1 mm without compromising the functionality of the final assembly. This allows for flexibility in production and helps minimize waste, thus enhancing cost-effectiveness in manufacturing processes.

Understanding tolerances is vital for engineers, as it affects both the interchangeability of parts and the overall quality of the product. It ensures that while parts can vary slightly due to the realities of production, they still meet the necessary specifications for a successful design outcome.