During the manufacturing process, magnetism, most often measured in gauss, can be introduced into both non-magnetically conductive material (such as stainless steel) and magnetically conductive materials in numerous ways. In addition to contact with magnets, actions such as grinding, welding and machining can introduce magnetism that may be retained in the product.
Why Is It Important to Remove Undesired Magnetism?
Undesired magnetism can cause numerous, costly and time consuming problems in further production or for the end user.
In production, undesired magnetism can cause the following problems:
- Interference with machining as cuttings stick to components.
- Contamination that cannot be easily removed through normal parts washing processes.
- Arc blow in the welding process that can make welding difficult if not impossible.
- Problems with electroplating and e-coat that make these processes difficult if not impossible.
- Problems with automated visual inspection equipment as clinging debris provides false dimensional data.
- Causes increased bearing wear.
For the end user, the problems can be vast depending on the application.
How Is Demagnetizing (Degaussing) Accomplished?
There are multiple ways to reduce a components’ magnetic field, or degauss a product.
Degauss Through Heat
When a metal’s temperature is increased above its curie point, the magnetic domains inside the material become randomly oriented and its magnetic properties are removed. The curie points for specific materials can be found here. One common way materials may be degaussed is through heat treat, depending on how long and in what environment the product is treated.
Degauss Through Alternating Current
It is often not possible to heat a material above its curie point without introducing dimensional imperfections into the component. In this case, the use of an alternating current is preferable. An alternating current creates rapidly changing magnetic fields that disrupt the magnetic domains within the material. By passing the component through these changing fields, the component’s magnetization is reduced.
Once degaussing is complete, it is important to obtain a gauss reading to ensure the desired level of magnetism has been achieved.
What Field Strength/Gauss Level is Right For My Product?
Acceptable gauss levels are usually determined by the end user or design specifications which take into account further processing and end-user usage. Normally, a gauss reading of 2 or below is acceptable by most industry standards. Below is a list of field strengths and what effect they may have on products.
Gauss Readings and Corresponding Effects at that Level:
- 200 gauss = Permanent magnet
- 30 gauss = Interferes with welding
- 20 gauss = Metal cuttings (paper clip size) stick
- 10 gauss = Small metal debris/shavings stick
- 4 gauss = Metal dust sticks
- 0.25 – 0.60 gauss = Earth’s magnetic field at the surface
IPS Has Over 25 Years of Experience Solving Undesired Magnetism Challenges.
Contact IPS Today to Discuss Your Demagnetism/Degauss needs.