Anti-Vibration Mat Not Working? 8 Common Causes

An anti-vibration mat is quick to lay – and yet sometimes it doesn’t work. It is almost always due to one of the following causes. The good news: most of them can be fixed with little effort.

1. The mat is under-loaded

If the bearing pressure is too low, the mat hardly deflects and stays stiff. The natural frequency is then too high. Solution: reduce the support area (strips or pads instead of a full-surface mat) or choose a softer class.

2. The mat is overloaded

Excessive pressure leads to excessive deflection, settlement and premature wear. Solution: increase the area, use a stiffer class or a load distribution plate.

3. Resonance instead of isolation

If the natural frequency of the mounting is too close to the excitation frequency (ratio below √2), vibration is amplified. This is also critical during run-up and run-down. Solution: check the tuning – our isolation calculator shows the range.

4. Acoustic bridges bypass the mat

Rigid pipework, cable trays, bolts without resilient sleeves or mortar at the edge of the mat carry vibration past the mounting (acoustic bridges – the isolation is “short-circuited”). Solution: make connections flexible, isolate fixings resiliently and keep edges clear.

5. Uneven load distribution

If the centre of gravity is not central above the mounting, the machine deflects unevenly and tends towards rocking modes. Solution: match the bearings to the centre of gravity and adjust the support areas.

6. Wrong material for the environment

Oil, coolants, UV radiation, ozone or high temperatures can cause unsuitable elastomers to harden or swell. Solution: choose a suitable material, e.g. NBR for oil, EPDM outdoors.

7. The substrate is too soft

On steel platforms, intermediate floors or lightweight substructures, the substrate itself can vibrate. The mat then works less well than calculated. Solution: take the stiffness of the substrate into account and reinforce the substructure if necessary.

8. The problem is airborne noise

A mat reduces structure-borne noise – not the noise the machine radiates directly into the air. Solution: provide an enclosure or acoustic hood in addition.

New: Vibration Isolation Check. Check your planned mounting in two minutes for overload, resonance across the whole speed range, acoustic bridges and missing information – with a traffic-light result and optional frequency measurement using your smartphone. Open the Isolation Check →

Checklist before installation

Are the weight and centre of gravity of the machine known?
Bearing pressure calculated and suitable class chosen?
Excitation frequency at least three times the natural frequency of the mounting?
All connections flexible, no rigid connections?
Material suitable for media, temperature and weathering?

Frequently asked questions

Why has the vibration got worse since the mat was installed?

Usually the natural frequency of the mounting is too close to the excitation frequency of the machine. Resonance then occurs and the vibration is amplified. The remedy is a softer or more heavily loaded mounting.

Does an anti-vibration mat help against airborne noise?

No. A mat reduces the transmission of vibration into the floor (structure-borne noise). Airborne noise radiated directly by the machine is reduced by enclosures or acoustic hoods.

How do I measure success before and after installation?

The most meaningful approach is a vibration measurement at the same measuring points before and after installation – for example on the floor next to the machine and, if there are complaints, in the affected room. Make sure the operating conditions such as speed and load are the same, otherwise the values are not comparable. BS 6472-1 (UK) and DIN 4150 (Germany) describe how vibration in buildings is assessed; our Standards & guidelines page gives an overview.

How do I know when a mat needs replacing?

Typical signs are visible cracks, hardening or embrittlement, swelling due to oil, clearly uneven settlement or a noticeable decline in isolation. If the machine shifts out of alignment or rocks, the mounting should also be checked. More on long-term behaviour under Materials & technical data.

What if the centre of gravity is off-centre?

In that case, each bearing should deflect by roughly the same amount: more support area or more pads go under the heavier side, fewer under the lighter side. With a high centre of gravity or large forces, an inertia base can limit rocking modes. More in the glossary.

Can I bolt a machine down through an anti-vibration mat?

Not with plain bolts: a bolt that runs straight through the mat into the floor creates a rigid acoustic bridge and short-circuits the isolation. If the machine has to be anchored, isolate each bolt from the machine foot with resilient sleeves and washers so that there is no metal-to-metal contact, or use lateral stops with a resilient interlayer. More in our guide Anti-vibration mat not working?

Is your mat not working as expected?

Send us a photo of the installation and the machine data – we will find the cause and suggest a solution.

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