What is the difference between an interference fit and a clearance fit, and when might you use them?

How to Answer
Answer Example

Your interviewer will likely ask you knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. In this case, press fits and clearance fits are types of engineering fits that generally refer to the sizing of a hole and a shaft in General Dimensioning and Tolerancing (GD&T). This is a system for defining and communicating tolerances with two main regulating bodies: International Organization for Standardization (ISO) and American National Standards Institute (ANSI). Interference fits are in both systems, but clearance fits in the ANSI system are referred to as running or sliding fits (RC). An interference fit generally describes a shaft that is oversized relative to the hole, and therefore requires some considerable force to assemble. An RC or clearance fit is one where the shaft is smaller than the hole, enabling the two to slide or rotate when assembled.

"Both interference fits and clearance fits are types of sizing tolerances applied to a hole and a shaft. An interference fit describes a shaft that is oversized relative to the hole, whereas a clearance fit describes a shaft that is undersized relative to the hole. I would use an interference fit to permanently attach two parts that I do not want to separate, such as a ball bearing with an interference fit between a shaft and inner race. I know that sometimes these parts are heated and cooled in order to assemble without excessive force applied. I would use a clearance fit when I want two parts to be able to move or spin freely, such as the inside of a door hinge."

Next Question

How to Answer: What is the difference between an interference fit and a clearance fit, and when might you use them?

Advice and answer examples written specifically for a Mechanical Engineer job interview.

3. What is the difference between an interference fit and a clearance fit, and when might you use them?

How to Answer

Your interviewer will likely ask you knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. In this case, press fits and clearance fits are types of engineering fits that generally refer to the sizing of a hole and a shaft in General Dimensioning and Tolerancing (GD&T). This is a system for defining and communicating tolerances with two main regulating bodies: International Organization for Standardization (ISO) and American National Standards Institute (ANSI). Interference fits are in both systems, but clearance fits in the ANSI system are referred to as running or sliding fits (RC). An interference fit generally describes a shaft that is oversized relative to the hole, and therefore requires some considerable force to assemble. An RC or clearance fit is one where the shaft is smaller than the hole, enabling the two to slide or rotate when assembled.

Written by Jason Toby on October 12th, 2020

Answer Example

"Both interference fits and clearance fits are types of sizing tolerances applied to a hole and a shaft. An interference fit describes a shaft that is oversized relative to the hole, whereas a clearance fit describes a shaft that is undersized relative to the hole. I would use an interference fit to permanently attach two parts that I do not want to separate, such as a ball bearing with an interference fit between a shaft and inner race. I know that sometimes these parts are heated and cooled in order to assemble without excessive force applied. I would use a clearance fit when I want two parts to be able to move or spin freely, such as the inside of a door hinge."

Written by Jason Toby on October 12th, 2020

Next Question