What is negative allowance also known as?

Negative allowance refers to a situation where the dimensions of mating parts are adjusted such that they interfere with each other when assembled, resulting in a tighter fit than intended. This concept is crucial in machining and assembly processes, where even slight variations can impact functionality.

In this context, the term "interference" indicates that the dimensions of one part exceed those of the other in a way that they cannot be assembled without exerting significant force. This condition is typically designed intentionally in applications that require a close fit, ensuring that components remain securely joined during operation without the risk of loosening over time.

Understanding this principle allows engineers to strategically design parts that remain in place under dynamic conditions, offering durability and reliability in mechanical assemblies. Recognizing negative allowance as interference of metal helps optimally choose fits for different combinations of shafts and holes, affecting factors like wear, clearance, and assembly ease. Hence, negative allowance is accurately described as interference of metal in the design process.