Automotive Parts Hardness Testing

Methods of Testing Automotive Part Hardness

Welcome to Northern Industrial Manufacturing’s “Automotive Parts University”! In these quick-read, online articles we educate clients, customers, and anyone who loves all-things-automotive on the ins-and-outs of automotive parts manufacturing.

In this article the manufacturing experts at NIM explain testing the “hardness” of automotive parts.

Hardness is an important property of metal materials and parts where the part is resistant to plastic deformation. There are a couple types of plastic deformation, which means there are a couple types of hardness measurements. So therefore, there are a total of three testing methods for hardness: scratch hardness, indentation hardness, and rebound hardness.

Automotive Parts Scratch Hardness

Scratch hardness is the metal material’s resistance to plastic deformation from scratching or abrasion, especially by sharp objects or tools. It is only possible for harder materials to scratch softer materials. One of the tools used to measure the scratch hardness is the sclerometer. The sclerometer consists of microscopically measuring the width of the scratch made by a diamond scratcher. There are three scales made for the scratch hardness, Moh’s scale, Ridgeway’s scale, and Wooddell’s scale.

Automotive Parts Indentation Hardness

Indentation hardness is the metal material’s resistance to plastic deformation from indentation or compression, especially by sharp objects or tools. The testing method for indentation hardness consists of the tip of a sharp tool, controlled by force or displacement, indenting the material to create a curve. There are a couple of scales used for indentation hardness of metallic materials. These tests that are used for metallic materials are Vickers, Rockwell, and Brinell.

Automotive Parts Rebound Hardness

Rebound hardness is the metal material’s resistance to plastic deformation from “bounces”. These “bounces” are caused by a hammer tipped with diamonds dropped on it from a certain height. The rebound hardness of metal materials is measured by the scleroscope. The scleroscope drops a steel ball from a certain height onto the measured material. The ratio of the impact velocity and rebound velocity, both measured by a magnetic inducer, is used to calculate the hardness. The test scales used for the rebound hardness are the Lee rebound hardness and Bennett hardness tests.

In conclusion, the hardness of metal materials can be determined with several different tests.

Automotive Parts Hardness Testing | Michigan

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