Holding force is a measure of the strength of a maglock. In the UK and the rest of Europe, it’s usually measured in kilograms. In the United States and elsewhere, it’s measured in pounds. But what actually is holding force? And how much do you need for different types of electro-magnetic locking projects?
What is holding force?
Electro-magnetic locks consist of two parts: the magnet and the armature plate. When electric current is applied to the magnet, it generates a strong magnetic force. That force holds the armature plate and the magnet together, thereby holding the door closed.
Another term for holding force is ‘pull strength’. This measure indicates the amount of brute force applied perpendicular to the magnet that would be required to pull the magnet away from its armature plate.
However, bear in mind that the armature could be pulled away from the magnet in a sideways motion – this is called shear force and is not relevant to the holding capacity of the magnet and armature plate.
Finally, it’s also important to understand that holding force is also related to the width and height of the door in question. The door provides a force of leverage when pushed or pulled. The door’s dimensions impact the size of this force of leverage. In some cases, the leverage force can result in more than the holding force of the magnet when applied as a short, sharp shock.
What holding force is available?
Electro-magnetic locks come with a range of different degrees of holding force. In general, maglocks start at around 180kg and go up to around 500kg holding force. They also come in single and double models. It’s important that installers understand how different levels of holding force are more or less suitable for different doors.
Holding force for internal doors
For internal doors, the holding force required depends on the use of the door. If the door just needs to be held closed to prevent people freely gaining entry, then a 300kg maglock is plenty. In normal usage, nobody is going to exert 300kg of force on a closed door. Greater holding force isn’t necessarily needed just to manage controlled access to a certain room, floor, or area.
Holding force for secure internal doors
If the internal door is a secure door restricting access to a secure area or protecting valuable assets, then 300kg may not be sufficient holding force. You should consider the worst case scenario: a break-in. If an int
ruder broke into the building, they could feasibly break a 300kg maglock’s holding force with some effort. However, at 500kg, the door is not so easily forced.
If the internal door is designed to keep its contents secure, then we recommend 500kg holding force at a minimum. Higher holding force can also be achieved with double maglocks, transom housings, or magnetic handles which contain more than one magnet.
Holding force for external doors
External doors need some more consideration. There are two possible scenarios: either the maglock is designed only to keep the door closed, or it is providing the secure locking for the door.
If the magnet is only to hold the door closed during the building’s active hours, then a 300kg maglock is enough. In this case, there should be another alternative (preferably mechanical) locking device to ensure the security of the door overnight or when the building is empty. If the maglock is only in use (or the only lock in use) when the building is occupied to restrict access to authorised individuals, then the same 300kg principle applies as for internal doors.
The difference is when the maglock is the only locking device on the door. If the magnet is intended to provide security to keep the door closed and keep the building secure when unoccupied, then 500kg holding force is a minimum requirement.
Our tech support team are regularly contacted by installers looking for help with their projects who make this mistake. Always remember: a 300kg maglock does not provide enough holding force to secure an external door.
Why is it important to choose the right holding force?
Security is the primary reason to ensure that you choose the right lock with enough holding force. If you are relying on a magnet with insufficient holding force, you are exposing yourself to the risk of a security breach through brute force. If you are ever unsure how much holding force you need, go for more. Or you can call CDVI Installer Support for advice.
I’m still unsure what holding force I need
If you need help, you can contact CDVI Installer Support at any time. Our team are experts with decades of experience. We’re here to advise and help wherever we can.
During our working hours, we’re available on the phone, via web chat, and with emails. Outside of office hours, send us an email to firstname.lastname@example.org and we’ll get back to you as soon as possible.