×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

*
*
*
*

Thanks. We have received your request and will respond promptly.

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

Altering Magnetic Field Strength at a Radius

thread340-503230

Altering Magnetic Field Strength at a Radius

Altering Magnetic Field Strength at a Radius

(OP)
Hello,

Please forgive my lack of knowledge on magnetism. I have an application in which I need a ring magnet of fixed strength on a piston to trip a sensor (reed switch) a certain radius away from the axis of travel (greater than the OD of the magnet). The sensor requires a field strength of a certain range. If I need to keep the sensor location fixed, can I tweak the Gauss it sees by placing another ring of steel (or aluminum or stainless) around the magnet? Will this redirect the field lines more through the outer ring and less through free space where the sensor is? The magnet is described as being axially magnetized, N42.

RE: Altering Magnetic Field Strength at a Radius

A drawing would clarify any misconceptions that arise from a verbal description.

Nevertheless, there's not much you can do to concentrate the field as you describe. Putting something at the sensor end might possibly improve things.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Altering Magnetic Field Strength at a Radius

You may be able to create steel pole pieces for the magnet and focus the field more.
A sketch would help a lot.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Altering Magnetic Field Strength at a Radius

possible. the effective way is to increase your ring magnet thickness. Attaching a steel ring to the magnet at the reed switch side could also work, however attaching to the other side could weaken field strength depending on their relative locations.
Aluminum or austenitic stainless won't have an effect, while martensitc or ferrite stainless are ferromagnetic.

RE: Altering Magnetic Field Strength at a Radius

(OP)
My main concern is having too great of a magnetic field, since the sensor has an upper limit as well as lower limit on Gauss. Experimenting with different sized magnets is less practical for us. I know there isn't really such thing as magnetic shielding, hence my question around redirecting the field. Here is a sketch.

RE: Altering Magnetic Field Strength at a Radius

i thought your reed switch was located along the axial of the magnet, such that adding a steel ring would increase the flux strength. With the sensor located on top of the radius of the magnet, adding a steel ring could weaken the flux the sensor "sees", guiding some flux away from senor.

Yes magnetic shielding does exist. you can have a design to even shield all magnetic flux, with zero Guess going through the sensor.

RE: Altering Magnetic Field Strength at a Radius

(OP)
Thank you for all of your responses so far.
Yes, the sensor is located some radius away from the magnet's axis of travel so that when the piston reaches a certain linear position, the sensor is tripped.
Since there is a piston cap above the magnet (not seen in the sketch), I am thinking of stacking ferritic rings as needed around the magnet (thinner than or equal to the magnet thickness itself) to redirect some of the flux and lessen the field the sensor sees. Am I understanding correctly?
I did not know about the shielding, sources I read said otherwise but then that's why I also came back to this website.

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