---
title: Rockwell Hardness (HRC, HRB): Meaning on a Print | Wolf Machine
url: https://wolfmachinenv.com/glossary/rockwell-hardness/
business: Wolf Machine & Fabrication, Inc.
address: 4812 Longley Ln, Reno, NV 89502
phone: (775) 359-5570
hours: Shop Monday-Friday 7:00 am-3:30 pm; closed Saturday and Sunday
type: Metal and plastic fabrication and machining (custom and CNC machining, welding, metal and plastic fabrication, gearbox and part repair, align boring, metal spray)
---

[Photo: Stock photo: gloved hands measuring a part with a digital caliper]

- [Home](https://wolfmachinenv.com/)
- [Glossary](https://wolfmachinenv.com/glossary/)
- Rockwell hardness

# Rockwell hardness

Rockwell hardness is a number that shows how resistant a metal is to a standard indenter pressing into it, with a higher number meaning harder. On a drawing it appears as a callout such as 58 to 62 HRC, and it tells the shop how hard the finished part must be.

Stock photo: gloved hands measuring a part with a digital caliper

Hardness is written on a print when wear, strength or edge life matters. The Rockwell test is the most common way to measure it because it is quick and leaves only a small mark.

## The scales

The test presses a diamond cone or a steel ball into the metal under a set load and measures the depth of the dent. The Rockwell C scale (HRC) uses the diamond cone and is used for hardened steels and tool steels. The B scale (HRB) uses a steel ball and is used for softer metals such as mild steel, brass and aluminum. The method is described in the ASTM E18 standard.

A hardness callout may also be a range, which leaves room for the heat treatment, or a minimum. Hardness tells you something about strength too: for many steels, a higher number means a higher tensile strength, which is why a quick Rockwell check can confirm that a part has the properties the drawing expects.

## What it means in the shop

Hard parts are cut differently. A part machined in its soft state is hardened, then finished by grinding, which is the normal order for [tool steels](https://wolfmachinenv.com/materials/tool-steels/). Cutting a part that is already hard needs slower speeds and tools made for it.

If your print calls for a hardness, make sure the callout says where it is measured. If the part is a repair, tell us what the original was. Hardness also affects welding, as covered in [heat-affected zone](https://wolfmachinenv.com/glossary/heat-affected-zone/).

### Sources

- [ASTM E18, Standard Test Methods for Rockwell Hardness of Metallic Materials](https://www.astm.org/e0018-22.html) (2026-10-18)
- [Rockwell scale (overview)](https://en.wikipedia.org/wiki/Rockwell_scale) (2026-10-18)

### Talk to the shop

[(775) 359-5570](tel:(775)%20359-5570)

| Monday to Friday | 7:00 am - 3:30 pm |
|---|---|
| Saturday and Sunday | Closed |

[Request a quote](#quote)

### Keep reading

- [Tool steels](https://wolfmachinenv.com/materials/tool-steels/)
- [Tool and die work](https://wolfmachinenv.com/services/tool-and-die-work/)
- [Steels and steel alloys](https://wolfmachinenv.com/materials/steel-and-steel-alloys/)

## See also

[Heat-affected zone (HAZ)](https://wolfmachinenv.com/glossary/heat-affected-zone/) [Tolerance](https://wolfmachinenv.com/glossary/tolerance/) [Surface finish (Ra)](https://wolfmachinenv.com/glossary/surface-finish-ra/)

## Where this comes up

[Bronze](https://wolfmachinenv.com/materials/bronze/) [Steels and steel alloys](https://wolfmachinenv.com/materials/steel-and-steel-alloys/) [Tool steels](https://wolfmachinenv.com/materials/tool-steels/)

[Photo: Stock photo: a lathe turning a bar, hot chips flying]

## Request a quote

Tell us what you need, attach a drawing or photos of the part, and we will get back to you during shop hours. Free consultations; prompt estimates.

[Call (775) 359-5570](tel:(775)%20359-5570)

- From your specifications, drawings or samples. We can also assist you in designing your product or part.
- Free consultations and prompt estimates
- Stands behind the work: Our rates are very competitive and our quality is second-to-none. Wolf Machine stands behind the work we perform.
- Company accounts: all major credit cards, or we can open an account for your company

Shop hours Monday to Friday, 7:00 am to 3:30 pm. Send your request any time and we will get back to you during shop hours.

Stock photo: a lathe turning a bar, hot chips flying