Safe Handling of Neodymium Magnets Based Upon Size
By: Michael Brand, President, SM Magnetics
Almost every week we hear stories about damaged magnets, pinched fingers, or even worse, injuries to individuals caused by strong magnets. When we discuss this with our customers, we usually find a common theme…safe handling practices are not in place for each phase of the product development cycling.
Each phase of product development cycle….prototype, EVT, DVT, and mass production…. has different handling issues. Each application is different and safe handling is critical to protect individuals and magnets, but different sized magnets require different considerations. Below are suggestions and considerations to help with safe handling of different sized magnets from prototype through production.
Micro Magnets – 0.1mm – 1.0mm
- Use plastic tweezers and not metal.
- Keep micro magnets in the same area at all times when not in use so they can be located easily. Spreading them out in a work area may make it hard to relocate them, or they may attract and stick to other ferrous materials.
- Neodymium micro magnets should never be placed under the skin due to allergies and possible complications related to exposure to neodymium, iron and boron.
- Use a microscope or magnifying glass when handling micro magnets to avoid damage to the magnets and for proper placement in the application.
- For applications using micro magnets in EVT, DVT, or mass production, packaging should be considered carefully to protect the magnets, make handling by the production staff easier, and ensure cleanliness of the magnet. Work with the magnet or magnetic assembly supplier to assist with packaging suggestions and requirements.
- Train staff how to handle micro magnets that contain parylene or other coatings that can be scratched or damaged easily. This is especially important in medical applications.
- Keep a medium-sized magnet available in case you need to pick up or locate micro magnets that are dropped on carpet, in a place that is tough to reach, or just not able to be seen.
- Keep the magnets in a clean environment to avoid foreign materials attracting to the magnets.
Small Magnets 1.0mm – 6.35mm
- Small magnets can be more fragile and easily break if hitting something, especially another magnet.
- If these are less than 2.0mm they can easily get lost or attached to something other than the prototype. Keep in the same area when not in use so they can be easily located.
- Use spacers between magnets if possible so they can be separated easily. If no separator is used, slide the magnets apart to separate. When putting them back together without separators, do not slap them together, as this could cause cracking or chipping.
- It is safest to connect two magnets in the following way: Place the face of one magnet on the corner of another magnet. Once the face is against the corner of the other magnet, carefully slide them together so they are face-to-face.
- The packaging of small magnets is important when assembling these during production. Work with the supplier to develop packaging that is safe and effective for production staff.
- Keep the magnets in a clean environment to avoid foreign materials attracting to the magnets. If foreign bodies attach to a small magnet, pat the magnet with scotch tape or masking tape to remove any foreign materials.
- Fingers and hands get pinched, bleed or get broken when caught between magnets that snap together.
Medium Magnets 6.35mm – 25.4mm
- These will become much stronger magnetically than small magnets and will attract to ferrous materials from a further distance. Keep steel tools at a distance from the magnets.
- Be aware of items close to the magnets that can jump toward the magnets and potentially break or chip them. For example, paperclips, pins, needles, magnetic wire, and small steel tools.
- Use spacers between the magnets that are about ½ the size of the largest dimension. For example, if a diameter is 1”, then use a non-magnetic spacer that is 0.5”. Suggested spacers are plastic, wood, and cardboard. When putting the magnets back together, use the spacer as a cushion and tool to help bring the magnets back together without damage. Remember, fingers and hands can get pinched, bleed or get broken when caught between magnets that snap together so be slow, precise and focused when handling them.
- The packaging of medium-sized magnets is critical in EVT, DVT, and mass production. Determine the appropriate packaging that includes the quantity per package, the packaging materials and the appropriate spacing needed between magnets. This will allow production staff to easily handle and remove them and will protect the magnets and coating. Work with the supplier to determine if special packaging or packaging materials should be considered.
- Never leave magnets unattended. Engineers like to play with magnets, so an unattended magnet can be seen as a project, toy, or experiment.
- Label any package, box or carton that has magnets with a “caution” sticker or hand-written note stating there are magnets inside. This will give notice to individuals who need to avoid magnets.
- If possible, have these magnets put into a sub-assembly so there is one less handling operation. Most magnet suppliers will make a sub-assembly using steel or some other material.
- Keep the magnets in a clean environment to avoid foreign materials attracting to the magnets. If foreign bodies attach to a medium magnet, pat the magnet with scotch tape or masking tape to remove any foreign materials.
Large Magnets – >25.4mm
- Always wear safety glasses when handling. If a magnet crashes into another ferrous object it may splinter.
- Always wear gloves with large neodymium magnets to avoid pinching. Remember, fingers and hands can get pinched, bleed or get broken when caught between magnets that snap together so be slow, precise and focused when handling them.
- Large magnets can quickly be attracted to surrounding ferrous materials. Keep them at a safe distance from each other. As a general rule for large magnets, use 15 times the largest dimension as a safe distance. So, if the largest dimension is 2”, keep the magnets 30” from each other, or from other ferrous materials.
- Keep the packaging that the magnet arrived in so you can use it for storage if needed. Many large magnets are installed into equipment, so keep them safe before, during and after installation.
- Control other items around the magnets that are ferrous. Many accidents happen because pliers, screwdrivers, knives, pins, and other ferrous objects jump toward the magnet instead of the magnet jumping toward the other object.
- Watch others who want to “play” with the magnets. Tell them “no”. I once watched a person think it would be fun to take two 1” spheres and place them on each side of his nose. When we left the hospital later…..
- Have a designated area to place the magnet when not using it. This area should be free of tools and other ferrous items.
- If using large magnets in applications in EVT, DVT or mass production, discuss packaging with the magnet supplier. Consider how the assembly staff will handle these large magnets and make sure the packaging is safe and efficient for them.
- If possible, have these magnets put into a sub-assembly so there is one less handling operation. Most magnet suppliers will make a sub-assembly using steel or some other material.
- Keep the magnets in a clean environment to avoid foreign materials attracting to the magnets. If foreign bodies attach to a large magnet, pat the magnet with scotch tape or masking tape to remove any foreign materials.
- For a good video that shows how dangerous large magnets can be, click here.
General Guidelines
- Don’t let small children play with magnets. These are not toys, and should be considered a hazardous or choking material.
- Neodymium magnets coated in nickel coating may cause an allergic reaction.
- Neodymium magnets will oxidize if not coated. Select the correct coating for your application.
- Keep magnetics away from electronics. Although electronics may be shielded, a large, strong magnetic field may have an effect on the electronics.
- Never swallow magnets. This may seem obvious, but there have been instances where magnets have been ingested.
- Use common sense. Magnets can move by themselves if close enough to another magnetic field or steel. Look around and make sure the area is safe and clean.
About SM Magnetics: SM Magnetics is a privately-owned company which provides assistance with magnets, magnetic circuit design, engineering support, and production. For more information, log on to our website, www.smmagnetics.com, or contact us at 205-621-8841.
