Anti-Vibration Mounts

Anti-vibration mounts (also called vibration isolators, rubber mounts or AV mounts) sit between a vibrating machine and its supporting structure. Their job is to absorb dynamic motion so it doesn't transmit into the floor, walls, ductwork or neighbouring equipment. Done properly, isolation cuts airborne and structure-borne noise, protects sensitive instruments and bearings, extends the life of the equipment itself, and stops vibration cracking welds, fasteners and concrete around the mount points. AIMS Industrial stocks 108 mount and isolator lines from our Sydney warehouse — Mackay flange isolators, Conflex heavy-duty mounts, cylindrical bobbin mounts, multicushion isolators, levelling feet and pads — for HVAC, pumps, electric motors, compressors, generators, mining plant and machine tools across Australia.

Quick Reference — Mount Selection by Application

Mount Categories

AV mounts split into eight working families. Each one solves a different combination of load, frequency and environment.

Cylindrical (Bobbin) Mounts

Rubber cylinder bonded to two threaded steel inserts. Male-male, male-female and male-buffer configurations in 40, 55 and 65 Shore hardness. Loads in both compression and shear, which makes them the workshop default for small motors, fans, compressors and general light-to-medium machinery. Common sizes 20×15 through 100×40 mm with M6, M8, M10 and M12 threads. Softer compounds (40 Shore) deflect more and isolate better but allow more equipment movement; harder compounds (65 Shore) carry more load with less travel.

Conical Mounts

Rubber-to-metal bonded with a conical profile that loads predominantly in shear, with some compression. The geometry gives a higher load rating per unit footprint than cylindrical mounts and slightly softer behaviour, which lifts isolation efficiency. Common on packaged industrial machinery, gensets and skid-mounted plant.

Sandwich and Buffer Mounts

A rubber pad chemically bonded between two flat steel plates, loaded in pure compression. Simple, robust, predictable. Used as foundation pads under fixed machinery, as buffers on conveyors and presses, and as the working element inside Mackay Conflex isolators for compressors, pumps and centrifugal plant.

Flange Isolators (Mackay M110, M114, M140, BRB)

Bonded rubber discs with a steel flange for bolting the equipment foot. The Mackay range covers light-duty M110 and M114, heavy-duty M140 and the BRB series, plus MD and recessed types for low-profile mounting. Designed for electric motors, generators and industrial fans on fabricated base frames. Mackay is Australian-made — see the broader Mackay range for the rubber bellows, engine mounts and bonded rubber products that share the same engineering pedigree.

Spring Mounts (Open and Housed)

Coiled steel springs, either open (exposed spring sitting in a pressed steel cup) or housed (spring inside a steel enclosure with a levelling bolt). Springs out-isolate rubber at low frequencies, which makes them the right answer for large HVAC plant, chillers, big reciprocating compressors and any equipment where the disturbing frequency drops below about 20 Hz. Housed mounts add a neoprene acoustic pad in series with the spring to break the steel-to-steel high-frequency path.

Air Mounts

A reinforced rubber bellow inflated with shop air, sitting between two steel plates. The pressure (and therefore the natural frequency) is adjustable in service. Used for precision applications — coordinate measuring machines, optical benches, lab instruments — where natural frequencies of 1–3 Hz are needed to isolate from floor vibration.

Wire Rope Isolators

Loops of stranded stainless steel cable (typically 316) clamped between two aluminium or stainless bars. The cable deforms in shear, compression and roll to absorb both vibration and shock simultaneously. Marine, defence, mining and military applications dominate — anywhere a mount has to survive saltwater, oil contamination, temperature extremes and shock loads that would destroy a bonded rubber mount.

Anti-Vibration Pads

Preformed pads in cork-rubber, neoprene or layered composite. Cheap, simple, no through-bolt required. Sized by area for a target load per cm². Used as foundation pads under static machinery, under HVAC condensers, behind machine tool levelling feet, and as a quick fix where a proper mount won't fit.

Isolating Washers, Grommets and Bushes

Small-component isolation — for fan housings, electronic enclosures, fasteners on vibrating panels and brackets. Typically natural rubber or neoprene with a steel through-sleeve to take fastener clamp load without crushing the rubber.

Material Properties — Pick the Right Compound

Wrong material is the number one cause of premature mount failure. Oil contamination on natural rubber is by far the most common — the rubber swells, softens and tears within months. Get the compound right at selection and the mount lasts 10–20 years.

Natural Rubber (NR)

Best damping characteristics of any common elastomer, excellent fatigue life, low cost. Operating range roughly −30 °C to +70 °C. Not oil resistant — keep away from hydraulic oil, lubricating oil, diesel and most solvents. The default compound for general machinery isolation in clean dry environments.

Neoprene (Chloroprene, CR)

Oil resistant, weather resistant, flame retardant. Operating range roughly −40 °C to +100 °C. Slightly less damping than natural rubber but far more forgiving in oily, outdoor or marine environments. The right choice for engine mounts, pumps near oil systems and outdoor HVAC.

EPDM

Excellent UV, weather and ozone resistance. Operating range −50 °C to +120 °C. Good steam and hot water resistance. Poor oil resistance — never use near hydrocarbons. Suits outdoor isolation, rooftop HVAC and steam plant.

Nitrile (NBR)

Fuel, oil and hydraulic fluid resistant. Operating range −30 °C to +100 °C. The compound for hydraulic power packs, fuel pumps, lubricated gear units and any application where oil splash is unavoidable.

Silicone

Extreme temperature range −60 °C to +200 °C, excellent ozone and UV resistance. Lower load capacity and damping than natural rubber, higher cost. Used where temperature alone disqualifies other compounds — kiln plant, exhaust systems, hot motor housings.

Polyurethane (PU)

High abrasion resistance, high load capacity, oil and fuel resistant. Operating range −30 °C to +80 °C. Less damping than rubber, so isolation efficiency is lower for a given deflection — but excellent for high-load buffer and bump-stop applications.

Selection Methodology

Mount selection is driven by four numbers: static load per mount, disturbing frequency, target isolation efficiency, and the deflection the mount can give you under that load. Skip any one of them and you're guessing.

Step 1 — Static Load per Mount

Total equipment mass divided by the number of mount points, adjusted for the centre-of-gravity offset. A 600 kg pump and motor skid on four mounts is not 150 kg per mount unless the centre of mass sits dead centre. For most pump-motor skids, the motor end loads about 60–65 % of the total. Add 10–20 % for dynamic load on top of static.

Step 2 — Disturbing Frequency

The primary vibration frequency of the equipment, in Hz. For an electric motor, frequency = RPM ÷ 60. A 1450 RPM 4-pole motor disturbs at 24.2 Hz. A 2900 RPM 2-pole motor disturbs at 48.3 Hz. Reciprocating compressors and engines disturb at running frequency plus harmonics — get the manufacturer data sheet.

Step 3 — Required Isolation Efficiency

Typically 80–95 %. Office and laboratory environments target 95 %+. General industrial plant targets 80–90 %.

Step 4 — Natural Frequency Target

The natural frequency of the mount-and-equipment system (fₙ) must be well below the disturbing frequency (f_d) for isolation to work. The ratio f_d / fₙ drives isolation efficiency:

• Ratio 1.41 (√2): 0 % isolation — the threshold below which mounts amplify rather than isolate
• Ratio 2.0: 67 % isolation
• Ratio 3.0: 89 % isolation
• Ratio 4.0: 94 % isolation
• Ratio 5.0: 96 % isolation

Aim for a ratio of 3 to 5 for general industrial work. Higher ratios (softer mounts) cost more, allow more equipment movement and can make piping connections difficult — but isolate better.

Worked Example — 200 kg Pump on a 1450 RPM Motor

Pump skid total mass 200 kg on 4 mounts. Centre of mass centred, so 50 kg per mount static. Motor RPM 1450, so disturbing frequency 24.2 Hz. Target isolation 90 %, so ratio 3.16, so target natural frequency 24.2 ÷ 3.16 = 7.65 Hz. The mount must deflect about 4.3 mm under 50 kg static load to give a 7.65 Hz natural frequency. Cross-reference the mount manufacturer's deflection curves — for Mackay M110 in 55 Shore that's the published load point. Pick that mount, four off, done.

Isolation Theory — Why Soft is Right

The instinct most engineers have is to choose a stiff mount because the equipment "shouldn't move." That instinct is wrong, and it's the root cause of most isolation failures in the field.

For a mount to isolate, the system natural frequency has to be lower than the disturbing frequency by a factor of at least √2 (1.41). Below that ratio, the mount amplifies vibration — at resonance (ratio = 1) the transmitted force is many times the input. Above √2, isolation begins. By ratio 3, you're at 89 % isolation. By ratio 5, 96 %.

That means soft mounts are usually right. The equipment will move a few mm under operation — that's the mount doing its job. If a manufacturer's installation guide says "the unit must not move more than 1 mm" they're either being conservative for shipping reasons or they don't understand isolation. Coordinate with the piping engineer on flexible connectors and you can let the equipment move enough to actually isolate.

The exception is impact and shock loads — drop hammers, presses, fork lift impacts. There you need stiffness to prevent runaway motion, and you build in damping (often via a sandwich or buffer mount) rather than chasing low natural frequency.

Industry Applications

HVAC and Mechanical Services

The largest single market for AV mounts in Australia. Rooftop AHUs, chillers, cooling towers, in-line fans, pumps in plant rooms. Spring mounts dominate large chillers and reciprocating compressors. Neoprene flange isolators handle in-line pumps. AV pads sit under condenser units. The driver is acoustic — preventing structure-borne hum reaching occupied spaces — and the design is typically specified by the consulting engineer.

Mining

Heavy compressor isolation in Pilbara, Bowen Basin and Goldfields plant rooms. Crusher and screen plant isolation on fixed structures. Wire rope mounts on mobile plant — drill rigs, mining trucks, generator sets — where shock loads and salt or dust environments destroy bonded rubber. Mackay BRB and Conflex are typical for fixed compressor work.

Food Processing and Pharmaceutical

Washdown environments need stainless or chemically resistant mounts — EPDM or neoprene rather than natural rubber. Pump and fan isolation under sanitary plant. Stainless levelling feet for hygienic machinery floor mounting.

Marine and Shipbuilding

Brisbane, Sydney, Henderson and Williamstown yards. Wire rope mounts dominate — main engine soft-mounting, generator isolation, weapon-system shock mounting on naval vessels. Neoprene for above-deck auxiliary plant. Bonded rubber engine mounts for smaller commercial vessels.

Defence and Naval

Osborne (SA) submarine and surface combatant build. Wire rope isolators dominate because of military shock specifications — MIL-S-901 grade hull-borne shock plus continuous vibration. Bonded rubber mounts also used for ancillary plant where shock spec is less severe.

Manufacturing and Machine Tools

Levelling feet under machine tools (lathes, mills, machining centres) — for alignment, load distribution and a basic level of floor vibration break. Bonded rubber pads under presses and stamping machinery. Spring mounts under large CNC machines where floor vibration would degrade surface finish.

Wire Rope Mounts — The Specialty Class

Wire rope isolators (sometimes called cable mounts or stainless steel mounts) are a category of their own. Loops of stranded stainless steel cable clamped between two metal bars, working in compression, shear and roll. They handle three conditions other mounts can't:

• Combined shock plus vibration — military and naval shipboard equipment, mining plant on rough roads, drop-tested electronic enclosures.
• Hostile environments — saltwater, oil, fuel, solvents, temperature −60 °C to +200 °C. 316 stainless cable handles what bonded rubber cannot.
• Three-axis isolation from a single mount — the cable deforms in all three directions, where most rubber mounts are optimised for one or two axes.

The trade-off is cost (typically 5–10× a bonded rubber mount of equivalent load capacity) and lower damping than natural rubber. For defence, naval, mining mobile plant and marine engine soft-mounting, the maths usually works out.

Standards Reference

Anti-vibration mount selection in Australian industry references several standards. [VERIFY:] edition years for AS 2670, ISO 2017 and ISO 10846 before customer-facing use.

• AS 2670 — Mechanical vibration: evaluation of human exposure to whole-body vibration. Drives isolation requirements for vehicle, plant and machinery seating, and for occupied buildings near vibrating equipment.
• ISO 2017 — Mechanical vibration and shock: resilient mounting systems — characteristic measurement of vibration isolators.
• ISO 10846 — Acoustics and vibration: laboratory measurement of vibro-acoustic transfer properties of resilient elements. The reference for isolator dynamic stiffness data.
• ISO 10816 / AS 2625 — Mechanical vibration severity of machines with non-rotating parts. Used to set acceptable vibration limits on installed equipment.
• AS/NZS 1170 — Structural design actions. Relevant where dynamic loads from vibrating plant transfer to the supporting structure.

Compliance generally means: identify the vibration source frequency, calculate static load per mount, select an isolator with a natural frequency well below the excitation frequency, and confirm post-install with a vibration meter. For installations where vibration is a known compliance issue (rooftop plant near residential, hospital plant rooms), an acoustic and vibration consultant should specify the mounts and certify performance.

Brand Range at AIMS

The 108-line range at AIMS centres on Mackay — Australian manufactured, the dominant brand for industrial flange isolators, Conflex heavy-duty mounts, multicushion and engine mounts in the local market. The Mackay range covers M110, M114, M140 flange isolators, BRB series for heavy-duty applications, MD and recessed flange types, plus the full Conflex configuration set for high-frequency rotating plant. We supplement with cylindrical bobbin mounts (40/55/65 Shore, M6–M12), AV pads, levelling feet and wire rope mounts for specialty work. For brands or sizes we don't stock direct, we source through our distribution network — call us with the spec.

Companion Ranges and Accessories

AV mounts almost always pair with rotating equipment and structural fasteners. Complete your install from:

• Electric motors — single-phase and three-phase TEFC motors, the most common equipment sitting on Mackay flange isolators.
• Pumps and fluid handling — centrifugal, diaphragm, gear and positive displacement pumps that benefit from isolation.
• Flexible couplings — for shaft connection between motor and driven equipment, tolerant of the residual motion that isolated equipment naturally has.
• Rubber bellows and expansion joints — pipework flexibility around isolated pumps and chillers, so structure-borne vibration doesn't travel down the pipe.
• Bearings — the components most damaged by uncorrected vibration.
• Shims and shim stock — for setting equipment foot heights during mount installation and post-install alignment.
• Fasteners — high tensile bolts, washers and nuts for securing mounts to base plates and structural steel.
• Lubrication — for the rotating plant the mounts support.

AIMS' Note on Mount Selection

If you're selecting mounts for an application that matters — main plant in a hospital, rooftop AHU above offices, big compressor in a critical line — get the numbers right before ordering. We need five inputs to recommend correctly:

1. Equipment make, model and total mass (and ideally the centre-of-gravity location).
2. Number of mounting points and their spacing.
3. Operating speed (RPM) and any known vibration frequencies — from manufacturer data, condition monitoring or a vibration consultant's report.
4. Environment — indoor/outdoor, temperature range, oil or chemical exposure, washdown, marine.
5. Mounting space and clearance — height available, bolt pattern, any restriction on equipment movement.

With those five, our team can size mounts and quote the same day. For complex installations (large compressors, big chillers, anything noise-sensitive) we'll recommend you bring an acoustic and vibration consultant in early — the cost of a consultant is small compared with reworking a bad isolation job after install.

Companion Resources

• Industrial pumps guide — pump types, selection and the role of mount isolation.
• Electric motor guide — motor sizing and the framework for isolation selection.
• Electric motors in hazardous areas FAQ — Ex-rated motor selection and mount compatibility.
• Bearing maintenance guide — the downstream cost of uncorrected vibration.
• Flexible coupling guide — pairing couplings with isolation systems.
• Belt vs chain drives — drive choice and its effect on transmitted vibration.

Order Anti-Vibration Mounts from AIMS Industrial

AIMS Industrial stocks 108 anti-vibration mount lines from our Milperra warehouse for same-day dispatch on in-stock items across Australia. For mount selection by load and frequency, troubleshooting a vibration issue on existing plant, or volume pricing on a new installation, call (02) 9773 0122, contact our team or request a quote.