×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Hardness testing of spring material

Hardness testing of spring material

Hardness testing of spring material

(OP)
What are ways to test the hardness or the quality of manufacturing/heat treatment of the spring?

The problem with a normal hardness testing machine (eg a rockwell hardness testing) is that these are usually used for flat surfaces and will be difficult to make accurate on a round surface such as a wire.

Any deformation or cutting on the finished spring to make a flat surface will not work. The suppliers for the steel wire also cannot supply flat surfaces of the material.

Thanks in advance.

RE: Hardness testing of spring material

Spring wire are tested by tensile strength. The specification that the wire is supposed to meet defines the minimum and maximum tensile strength required. When you purchase a spring wire, make sure to ask for the manufacturer Certificate of Tests (C.O.T) not the C.O.C. It specifies the actual tensile test results made in the spring manufacturer facilities on the purchased wire batch, including prior and after heat treatment tests. If you do not trust the spring manufacturer you need to repeat the tests in a respected test lab.

RE: Hardness testing of spring material

hamsuplo,

Round wire/bar is routinely tested for hardness, and standards such as ASTM E18, ISO 3506, etc. account for the curvature by using a correction factor.

RE: Hardness testing of spring material

Microhardness on a mounted specimen is also employed. Keep in mind that any hardness conversions to tensile strength generally are not valid for spring wire. The main use for hardness testing on spring wire is to evaluate samples against the history of the wire you have been using, i.e. conformatory testing.

RE: Hardness testing of spring material

(OP)
Thanks.

Is the correction factor for the curvature added onto the hardness indicated by testing machine?

How does one test the tensile strength of a 3.2mm diameter round wire? We have a tensile testing machine (with several different grips/clamps for different materials)... Most of the grips can't be used.. the one that can is just a pressing clamp and the wire slides through very easily..

RE: Hardness testing of spring material

hamsuplo,

Yes, the correction factor is added to the indicated hardness to adjust the final hardness. For example, for a 6 mm wire sample, if the indicated hardness is 55 HRC, the cylindrical correction factor is 2.0, which means that the final hardness is 55 + 2 = 57 HRC. You must purchase an appropriate hardness testing standard such as ASTM E18 or ISO 3506 in order to properly perform hardness testing. Regarding the tensile testing of wire, you need to purchase the appropriate grips for small wire samples. Instron and other providers of universal test machines also supply different grips. You need to discuss your specific application with them.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close