# Lock Magnet

1. Feb 3, 2012

### josh.k.abbott

Hi

What is the minimum kgf (or N) of a magnet to hold a 4m x 2.5m door?

The door will be outdoor and wind can hit it. The function of the magnet is to keep it open.

Best regards
josh

2. Feb 3, 2012

### ardie

depends on the strength of the magnet and how you plan to keep the magnet in place. if you want the magnet to keep itself in place, then it needs to weigh just as much as the door. if you tie it to something then it may be able to hold.
it also depends on the conductivity of the door's materials. a 2 tesla magnet, is pretty expensive, but can create forces of roughly the same magnitude as one can pull or push with a hand.

3. Feb 3, 2012

4. Feb 4, 2012

### ardie

fortunately for you that website is telling you what the holding power is. It says that given that you use a VDS coil on the door, so that the magnet is in touch with the coil, the holding power is 490N, which translates to an object as heavy as roughly 49kg. So if the door is only say 20kg, then there's some degree of strength even with the winds. Although high winds can achieve much higher forces, on occasion.

5. Feb 4, 2012

### tasp77

On a practical note, maybe you want the magnet overcome at a lower wind speed than a higher one. A 10 km/hr breeze slamming a door shut won't be quite as annoying as a 90 km/hr wind gust doing it.

KABOOM!!