Printed from the blog of Lori Greene, AHC/CDC, CCPR, FDAI
Allegion
Email: lori_greene@allegion.com, Blog: www.idighardware.com or www.ihatehardware.com


May 26 2015

WWYD? Noisy Mag-Locks

Category: Electrified Hardware,WWYD?Lori @ 10:09 am Comments (14)
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mag-lock

These are not the same doors – these have a top rail instead of an HDB bracket.

I know that some of you will be able to help with this question from a contractor, who has all-glass doors with direct-hold magnets making noise when the doors close and when the mag-locks engage.  Originally, I thought he might have shear locks, which are notoriously noisy, but they are surface-mounted mag-locks, not shear locks.  The all-glass doors in question have brackets that slip over the top of the glass for the armature to attach to (HDB brackets) – I’m not sure if this affects the sound at all.

I’m thinking the closing speed/force on the closers could be adjusted to help close the doors more slowly and with less force to minimize the noise of the armature closing against the magnet, but if the engagement of the lock also makes an objectionable noise, what can be done?

If you have any ideas, leave a comment below, and thanks in advance for your help!

14 Responses to “WWYD? Noisy Mag-Locks”

  1. Lee Francisco says:

    I’ve thought about this before. What about a thin sheet of rubber material attached to the face of the door portion of the mag lock? Just enough to eliminate the metal on metal noise when the magnet engages but not enough to lessen the holding force.

  2. Tom Breese says:

    Could we add in a timing delay of some sort in the relocking, where we allow the door to be fully-closed via closer power, thereby allowing the magnet and armature to come into full contact w/ each other without magnetism? Then, the magnet is energized.

    If I’m understanding correctly, the magnet is being energized prior to the door being fully-closed, “sucking” the door closed which would cause the armature-to-magnet clapping noise.

    Just taking a shot here…

  3. CLIFF COHEN says:

    From the picture , these are double acting doors set up to swing only one way by the installation of the mag locks. To prevent the slamming of the doors into the armature we use a stop that CRl makes that has a plastic front that can screwed to the top of the header . this causes the door to stop at the stop installed and not by slamming into the mag lock. the piece is only about 1/2 x 6.

  4. John Rein, AHC says:

    The armature plate may bee too tight, it should be loose to allow the armature plate to mate properly with the mag lock.

  5. David Moyer says:

    The issue with any material applied to the surface of the maglock is it will reduce the holding force of the magnet. This is one issue with maglocks and how they are deffaced – any slight space between armature plate and magnet will reduce holding force. Also closers aren’t at fault – the door could close ever so gently and as soon as the lock is energized, people nearby will hear the “clank”. Is there rubber between the over-the-top bracket and the glass? This would minimize noise traveling thru the glass. Also, is there a rubber isolation material between door header and over-the-top armature bracket? This would minimize noise transmission into the header. They might be able to adjust armature plate to minimize gap between face of magnet / armature when door is closed. Other than these suggestions, in my experience, there will always be a noise as the magnet powers up and attracts the armature plate.

  6. Daniel Davis says:

    Possibly use a DPS on each door in series with the mag lock so it won’t energize until the doors are completely closed. Also , make sure the armature isn’t too loose as this adds to the noise. Along with previous comments there is only so much you can do to avoid the “clank” noise. I have noticed on properly installed mag locks used with auto operators will have almost no sound when they energize after the door is completely closed.

  7. Gary J. Bakken says:

    It appears these Herculite doors have head closers and is most likely why you have a head rail on the doors…to accommodate the closer arm. This head rail should have no impact on the noise you’re describing. A stop should be used, but most people seem to use the mag lock as the stop. Thus, your first noise would be when the door closes and the strike plate (also known as armature plate) hits the mag lock. You might be able to adjust the closers some to reduce this, but these closers seem to be somewhat limiting on this latch adjustment. These closers are most likely center hung, double acting closers, so I wouldn’t be surprised if you got a bounce off the mag lock when it closes. This leads me to the next issue. I would bet the strike plate doesn’t sit tight against the mag when closed and not powered. This gap between the mag and the strike plate is causing the second loud noise. When the magnet is powered, it pulls the strike plate in. The farther away it is (the larger the gap), the louder the sound. It’s why shear locks are so loud…distance to pull strike plate in to meet the mag lock. Moving strike plate closer to the mag or the mag closer to the strike plate will lesson this sound of engagement. In fact, if the gap is close enough, you won’t hear much sound at all. I just got off a job site and you can not tell when the mags engage. You can’t change this gap much with a shear lock, but you can with a face mount. Like many issues that occur in door hardware, the problem oftentimes is a result of the installation.

  8. Martin Badke aka lauxmyth says:

    I am going to disagree with even Lori on this one. Turn the closer force UP not down. Then you can control the speed to slow the latch swing speed. (While I have not seen it written in the literature, my expericence is that closers come out of the box to latch a typical door with a cylindrical latch. This is too fact for push/pull sets or maglocks.)

    I would also check the armatures are not too loose. It need only rock slightly and I have made them firmer by using some bigger rubber washers.

    Do not place anything on the face of the maglock nor the armature. The loss in holding power is very dramatic even with a single layer of packing tape.

    • Lori says:

      You can disagree with me any time! I don’t have the field experience you do, and I value your insight very much! 😀

  9. Martin Badke aka lauxmyth says:

    Oh, I knew you would not be too worried with debate on any point. I looked up the HDB install and it left me wondering the material for the armature holder and how much space is between it and the armature itself. This left me wondering at the source of the noise.

    One possiblity is if the door impact is causing the armature to hit the holder, it may be possible to add peel-n-stick felt to the BACK. (Since full glass doors are not fire rated, field modification like this need be carefully planned and thought out but do not compromise the rating.)

    Another source of noise is that of the armature hitting the magnet. If you slow the door, this is decreased but still will happen. Armatures can ring like bells when hitting and felt on the back may also help this. If the door has any speed at all, the armature will recoil off the magnet and since it is free now will ring. This makes it tempting to add a time delay to allow the armature to fully come to rest before energizing the magnet, but my experience is that the dull thud of the magnet grabbing is less than the ring off a bounce. Your ‘litres per 100 kms’ may vary.

  10. Mike O'Reilly says:

    I have a problem that may or may not be related. When the door closes the lock (the grey magnetic bit at the top of the door -it looks like the one at the top of the glass door in the picture above) makes a continuous (looud!!) humming sound. (you can easily hear it 20M away). There is a second one that does it as well but only sometimes. Anyone have any siuggestions as to what it might be and how to fix it?

    Thank you all so much

    Mike

    • Lori says:

      Hi Mike –

      I asked one of our electrical experts about this. He said:

      If it’s a shear lock, the shear locks did have a module that can cause that effect.
      Check the input voltage to make sure it is filtered and regulated, and a solid 12 or 24 VDC.
      Make sure all mounting hardware is tight.

      – Lori

    • Lori says:

      I also heard back from tech support and they said to make sure the locks are supplied with DC power – not AC as that can cause a hum.

      – Lori

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